A tuning tale: BLMs say lean, plugs say rich

[XfireZ51]

Trying to dial in the tune on the LT5. Just when I seem to be close to finalizing based on BLMs, I pull plugs and they don’t indicate what the BLMs are saying. Specifically, my plugs are a very dark brown suggesting the tune is rich but the BLMs are reading in the 133-135 range. I’m tuning to within a +/- of 3 to 128. The heads and top end have been ported, larger cams, and 3” exhaust w headers.
Here’s a pic of the NGK BKR5E-11 I am using. They’re gapped at .044”. The darker one is from the passenger side bank, the lighter from driver’s side.

[jss06c6]

Dominic,

This is interesting.. I've got my '91 dialed in to 128 on driver side and 133 on passenger side. Haven't made any PE changes yet, but the first pull on our new Dyno showed the engine to be very rich. Raw fuel spraying out of the exhaust! Still made 359/405 on a loaded Dyno. There is a lot left in the engine, but I'm still intrigued as to why, after porting and the engine is so rich at WOT. BLM's we're running 138-145 after porting using un-ported tune.

Watching and learning!

Steve

Sent from my XT1585 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[Ccmano]

Trying to dial in the tune on the LT5. Just when I seem to be close to finalizing based on BLMs, I pull plugs and they don’t indicate what the BLMs are saying. Specifically, my plugs are a very dark brown suggesting the tune is rich but the BLMs are reading in the 133-135 range. I’m tuning to within a +/- of 3 to 128. The heads and top end have been ported, larger cams, and 3” exhaust w headers.
Here’s a pic of the NGK BKR5E-11 I am using. They’re gapped at .044”. The darker one is from the passenger side bank, the lighter from driver’s side.

Air leak before or near the O2 sensor?
H
:cheers:

[XfireZ51]

Air leak before or near the O2 sensor?
H
:cheers:

No Hans. I logged before and after O2 sensor change. No significant difference.

[Ccmano]

No Hans. I logged before and after O2 sensor change. No significant difference.

Understood, but changing out the O2 sensor does mean you don’t also have a leak somewhere that hasn’t been resolved. That said a leak would affect one side or the other if it’s in the exhaust..
H

[XfireZ51]

Dominic,

This is interesting.. I've got my '91 dialed in to 128 on driver side and 133 on passenger side. Haven't made any PE changes yet, but the first pull on our new Dyno showed the engine to be very rich. Raw fuel spraying out of the exhaust! Still made 359/405 on a loaded Dyno. There is a lot left in the engine, but I'm still intrigued as to why, after porting and the engine is so rich at WOT. BLM's we're running 138-145 after porting using un-ported tune.

Watching and learning!

Steve

Sent from my XT1585 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

Steve,

If u enriched up the mixture to keep up w the additional air from the porting, the PE table is still set up for the stock VE tables. With more VE fuel, the PE multiplier are being used over a larger number. The VE and SA tables are the basis for practically everything else. Change them, and other parameters need adjustment because they”feed” off those tables.
One other modification that most don’t know about. The PE will be modified based upon the last Active BLM prior to going into PE mode. Anything over 128, and the ECM will add fuel beyond just what the PE muliple is. So if the motor is running somewhat lean based on the last BLM it sees, then the ECM will add a bit more cushion.
This is if u r tuning in C/L.

[XfireZ51]

The motor feels that it likes the BKR5E plug better than the 6E. I tried raising SA again but started to pick up some KC at a steady cruise as I had in a previous datalogs. The Knock occurs during steady cruise at about 1800-2000rpm and shows up when the road begins an incline. In the LT5, AE is based solely on MAP differential not TPS%, so I can maintain a steady foot on the throttle but MAP will change slightly and that’s when I will see the KC increment. So this is why I dropped timing. It was to eliminate the KC at steady speeds. Otherwise I don’t get KCs.
So my question is, did I drop timing to eliminate KC but in the meantime lower timing is giving me a more incomplete burn?
Am I creating s problem trying to solve a lesser problem?
__________________

[XfireZ51]

Been out of pocket for a bit so no progress. But, I'll be pulling the plenum here for two reasons: 1. Check to see if I am getting oil seepage into #2 cyl,possibly less in #4. If that proves negative, I will likely be sending injectors for cleaning and flow check. I'll be replacing knock sensor and tensioner since I'll be dropping coolant. Qjacks will be making this an easier chore Stay tuned.
Meantime, I have some new weatherstrip to put on doors.
LET THE WINTER BEGIN.;)

[XfireZ51]

So we move ahead. Before I start tearing into top end of motor, I thought I would first check the injectors thinking perhaps something obvious would show. I ran a resistance check on the injectors. The primaries ranged from 14.6-14.8 ohms, while the secondaries ohm'd out at 14.1-14.3. All pretty consistent. This does not definitively rule out injectors, but its a start. If I don't find evidence of a particular cylinder sucking in a bit of oil, I'll have the injectors cleaned and flow tested. This MAY have some relation to getting knock counts during cruise.
If I'm running rich in one bank, I would be tuning to balance that out causing possibly the opposite bank to be running a bit lean which, again, MAY induce knock on accelerator position change.

[WARP TEN]

This may be a little out of left field, but have you tried a slightly higher heat range of plugs? Maybe your plugs are running a little cool for your most typical driving and a change might show less discoloration. --Bob

[XfireZ51]

This may be a little out of left field, but have you tried a slightly higher heat range of plugs? Maybe your plugs are running a little cool for your most typical driving and a change might show less discoloration. --Bob

Bob,

I had NGK 5 heat range in there. Not sure I would go any hotter. And the ground strap was indicative of the correct heat range for the motor. The plug coloration is inconsistent, w #2&4 showing brown to dark brown, nearly black. The other plugs on that bank were closer to “normal” w #8 being the leaner of them. The left bank was ok, maybe a bit lean, and all of that is indicated by the BLM split left and right. It averages out to 126-131 BLM, but that may be a 124 v 137 split as an example.
Frankly, the Autolites, which are a “projected nose” plug, puts the spark closer towards the center of the chamber volume. And the motor runs noticeably smoother w them. And it shows in the resulting MPG increase.
I’ll ohm the coils and plug wires next.
I’ll take it step by step and try documenting it here.

[XfireZ51]

Well plenum in process of being pulled. Clearly have intercyllinder activity going on. Specifically on right side. So if right side is coming in rich, then left side n eds to go lean in order to balance. But if the imbalance is due to uncontrolled air flow, then u end up tuning to compensate making the opposite side too lean.
Gasket on the right is the passenger side of motor which is running rich. Pucs are showing both top and bottom of gasket.

[mhobtr]

Are you going to check the injector housing gaskets also?

[XfireZ51]

Are you going to check the injector housing gaskets also?

Yes. I’ll at least pull IH on right side. I’ll inspect from the top first to see if there’s a sign of oil seepage. By the looks of the plenum gaskets, I can see where at least part of the issue may have been originating.

[Ccmano]

Well plenum in process of being pulled. Clearly have intercyllinder activity going on. Specifically on right side. So if right side is coming in rich, then left side n eds to go lean in order to balance. But if the imbalance is due to uncontrolled air flow, then u end up tuning to compensate making the opposite side too lean.
Gasket on the right is the passenger side of motor which is running rich. Pucs are showing both top and bottom of gasket.

Dom, what is causing the discoloration of the plenum gaskets around each of the runner openings? Can’t tell from the photo. Is that oil or just sealer residue?
H
:cheers:

[XfireZ51]

Hans,

No sealer used on gaskets. I know Marc installs them dry. The wet spots are condensation. Its indicative of air leakage, and the worst of it is right around that #2 cylinder. Much less on left side of motor. I think the gaskets are FlatOut plenums. Frankly, I never liked their stuff. I just ordered a set from Jerry along w IH gaskets. The plenum bolts were properly torqued but pretty clear that plenum was not sealing against gasket. Interestingly, motor idled well and ran pretty well. Without a datalog and looking at the plugs, someone would have left it alone.

[Ccmano]

Hans,

No sealer used on gaskets. I know Marc installs them dry. The wet spots are condensation. Its indicative of air leakage, and the worst of it is right around that #2 cylinder. Much less on left side of motor. I think the gaskets are FlatOut plenums. Frankly, I never liked their stuff. I just ordered a set from Jerry along w IH gaskets.

If that’s the case you have quite a lot of air leakage. It will be interesting to see the IH housing gasket. I’m running the thicker gaskets Jerry offers, although I have found they require a retorque after a few days of running.
H
:cheers:

[XfireZ51]

Hans,

I think you will see this type film on most. What’s important is to see if the plenum is sealed at the perimeter from the outside and between cylinders. The film u see on the gasket is oily, likely from the presence of oil vapor from PCV. In particular here is that the #2&4 cylinders appear to be “sharing” the airflow which would explain the color of those two plugs specifically. The other cylinders have same film but to a much diminished extent and not the cross travel u see between these 2 cylinders. First pic is #2, second shows trace of flow between 2&4 similar to what we saw on gasket. In the other set of pics u can see the flow of the oil film down the runner from top of IH. So the question now is, do I stop there or go on to removal of IH’s as well?

[A26B]

Just for peace of mind, you might try screwing your plenum bolts into the injector housing, to just hand tight. Check to be sure the gap under the bolt head to the top of the injector housings is at least 1/16" less than the thickness of the plenum at each bolt hole location.

With blind tapped holes, it can be difficult to tell when the bolt is fully clamped or out of threads.

Also, about the allen drive pipe plug in the injector housing coolant port; What if it's seeping coolant into the adjacent intake runners? How would you tell unless it was significant? There is so little "meat" there to tap for that plug. I have always been concerned about it sealing properly with probably less than 2 threads engaged.

[XfireZ51]

Just for peace of mind, you might try screwing your plenum bolts into the injector housing, to just hand tight. Check to be sure the gap under the bolt head to the top of the injector housings is at least 1/16" less than the thickness of the plenum at each bolt hole location.

With blind tapped holes, it can be difficult to tell when the bolt is fully clamped or out of threads.

Also, about the allen drive pipe plug in the injector housing coolant port; What if it's seeping coolant into the adjacent intake runners? How would you tell unless it was significant? There is so little "meat" there to tap for that plug. I have always been concerned about it sealing properly with probably less than 2 threads engaged.

Jerry,

Thanks for the tips on checking bolt clamping. The allen plug has been there now for probably 7 years. No indication of coolant loss so far. The dampness u see on the gaskets is of an oily nature

[XfireZ51]

Pulled both IHs to discover some oil seepage, like ccmano, from PCV vents into cylinders. I did not realize that only two of the three apparent vents are functional on the cylinder heads. These pics are of both sides IH. The first being right side, but left side also showing some seepage. We see seepage into middle cylinders on each cylinder head. I also show the #6 cylinder plug as it correlates to the seepage we see on the Ih gaskets.

[Top Toy]

Looks like an oil control problem. I don't recall the details, but didn't you have some repairs done to the top end a year or so ago? Were the valve seals disturbed? Are those your original IH's? Are yours supposed to have plugs in the crankcase ventilation ports?

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[XfireZ51]

Looks like an oil control problem. I don't recall the details, but didn't you have some repairs done to the top end a year or so ago? Were the valve seals disturbed? Are those your original IH's? Are yours supposed to have plugs in the crankcase ventilation ports?

Sent from my HTC U11 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

Dennis,

Had a compression ring that cracked on #7 which Pete R&R’d. Yes original IHs.The crankcase vents match up w the heads. Last year we thought that may have been the issue w my oil usage but it turned out to be a broken compression ring. I think I documented it on forum.

[Paul Workman]

I've experienced the 'lean but rich' dilemma before. (It lead me to my purchasing a scanner which ultimately identified the problem.)

Anyway.... When I got a lean BLM, the PW went wide and the plugs were a dry, flat black sooty coated in appearance.

In your photos, is the one of the spark plug totally unmolested? I ask because there is a definite shine in the photo on the edges of the insulator and the ground strap too. That is very uncharacteristic of rich. If unmolested (e.g.,accidentally wiped or brushed against something), it looks to be a little more like either oil or antifreeze????

Lean but rich:

Air diluting the exhaust seen by the sensor
Failing O2 or connector to the ECM
An error in the tune

Shiny black (wet):

Oil
Antifreeze (the pix of the gasket suggests less than perfect seal)
Plug heat range too low

Checked your oil catch can recently?

Checked your antifreeze level over time (mileage)?

:happy1:

[XfireZ51]

Thx Paul. Based on what I see w gaskets, its oil getting in there.

[Ccmano]

Looks identical to what I found when I pulled my old high mile engine. In my case I am convinced it was due to age and mileage which resulted in the hardening of the gaskets and loosening of the IH bolts. That engine was burning considerable oil as a result. In this case it may simply be the result of reuse of the IH gaskets when the previous engine work was done, which I believe was the case. Generally, once gaskets are compressed they never again have the same sealing properties if used multiple times. Dom has done considerable data logging on this engine. Had there been a manifold/crankcase pressure issue it should have shown itself in the MAP sensor readings, which, as I understand, was not the case.

After researching my issue and now this one I am of the opinion that this condition is much more common than we think. Several factors come into play. Loose IH bolts is a known issue. Age, mileage and the resultant heat cycles harden the gaskets and loosen the bolts. The design, with crankcase oil vapor galleys, coolant passages and intake runners in close proximity, with only a thin gasket to seal, is not ideal. Generally, IH gaskets are not high on the list when “top end” work is done. IH’s are not generally removed unless more major work is done. Even then no one pays attention to the IH gaskets.

In this case I would simply replace the gaskets, reassemble and (blue) loctite the IH bolts, then monitor crankcase/manifold pressures.
H
:cheers:

[A26B]

Three important step for proper gasket sealing.

1. Insure gasket mating surfaces are completely cleaned and free of any oil residue which will impede gasket sealing

2. Check & insure the mating surfaces are perfectly flat. The gasket material we use is very high quality. Compressibility is 12~15% of the un-compressed thickness. Translated to real numbers, a 1/32" (0.03125") gasket will compress appx 0.004". Using this value as a guide, flatness should be held less than 0.002" A precision straight edge and feeler gauge are recommended.

3. Proper torquing sequence. The general rule of thumb is to start at the middle & work towards the ends in a x'ing pattern. My personal technique is to make 4 passes, #1 @ 1/3 of the full torque value, #2 @ 2/3, #3 @ full torque and the last pass again @ full torque.


True surfaces and proper technique don't require thick gaskets.

For EACH Injector Housing with staggered bolts, follow the same torque pattern concept as shown for the Plenum.

https://cdn10.bigcommerce.com/s-nkg90o/product_images/uploaded_images/plenumboltsequence.jpg

[XfireZ51]

Jerry,

Thx. That was going to be one of my questions. And I have been told that its better to use the thinner gaskets for clamping and sealing.

[XfireZ51]

Concurrently, w the contradictory BLM v spark plug readings, I have been chasing what was going on w getting knock counts during times of steady cruise and at a fairly specific area of the VE and SA tables. Been wary of this ever since I had the issue w a broken compression ring on #7 last year. Every thing I had read pointed towards knock being th cause. Turns out I could induce Knock and Retard by stabbing the throttle. Knock shows up both on the opening and closing of the throttle. I have been thinking that I needed to beef up the AE pumpshot. Meanwhile, I had continued to reduce timing and seeing a reduction in the knock counts. However, timing was getting to where it was at “stock” levels and there was still some knock showing up, at times with literally no changes happening in driving conditions, ie tps%, MAP, SA etc. It would just show up for just a few frames. Another ZR that I have been tuning had no knock w timing significantly higher than my own. Seeing the oil seepage into at least a few of the cylinders has me concluding that the knock and the plug coloration due to oil seepage are related. Oil has a lower detonation point than 93 Octane and has been costing me some spark advance. I have replaced the knock sensor as one of the those
“While u r there things” since I have no idea how long its been there and its inexpensive enough to swap it out.

[Paul Workman]

Concurrently, w the contradictory BLM v spark plug readings, I have been chasing what was going on w getting knock counts during times of steady cruise and at a fairly specific area of the VE and SA tables. Been wary of this ever since I had the issue w a broken compression ring on #7 last year. Every thing I had read pointed towards knock being th cause. Turns out I could induce Knock and Retard by stabbing the throttle. Knock shows up both on the opening and closing of the throttle. I have been thinking that I needed to beef up the AE pumpshot. Meanwhile, I had continued to reduce timing and seeing a reduction in the knock counts. However, timing was getting to where it was at “stock” levels and there was still some knock showing up, at times with literally no changes happening in driving conditions, ie tps%, MAP, SA etc. It would just show up for just a few frames. Another ZR that I have been tuning had no knock w timing significantly higher than my own. Seeing the oil seepage into at least a few of the cylinders has me concluding that the knock and the plug coloration due to oil seepage are related. Oil has a lower detonation point than 93 Octane and has been costing me some spark advance. I have replaced the knock sensor as one of the those
“While u r there things” since I have no idea how long its been there and its inexpensive enough to swap it out.

You may have significant carbon deposits in some chambers as result of the oil seepage issue. So, once the gasket issue is resolved, you may want to de-carbon the motor first before doing a lot of hocus-pocus (VE/SA manipulation).

Did both heads come off to inspect the motor as well as replace the parts related to the broken ring? - seems curious you'd have a leaking gasket(s) issue a year after they were (presumably) replaced, no?

[XfireZ51]

You may have significant carbon deposits in some chambers as result of the oil seepage issue. So, once the gasket issue is resolved, you may want to de-carbon the motor first before doing a lot of hocus-pocus (VE/SA manipulation).

Did both heads come off to inspect the motor as well as replace the parts related to the broken ring? - seems curious you'd have a leaking gasket(s) issue a year after they were (presumably) replaced, no?

Ah yes. Pete did the work. He replaced rod bearrings as well because they showed signs of wear.

[XfireZ51]

Due to the holidays, and waiting for gaskets, haven’t done much. However, I did take the opportunity to scrape some of the carbon gunk off the back of some of the intake valves. Some had more carbon build up than others. Driver’s side semed to more of an issue than the passenger side. Also, the primaries were clean while the carbon build up appeared mainly on the secondaries. That leads me to suspect that the carbon buildup occurs during idling situations since secondaries are off only during that time and primaries continue to spray fuel.
I’ve had these injectors for 10 years, so “while I’m there”, I’ve decided to have them flow tested and cleaned. May as well certify they operate at “nominal” levels before buttoning up the top end. We’ll see if any of them may be sub-optimal.

[Hib Halverson]

Couple of comments here...

1) NGK 5 heat range is too hot for any LT5 other than show cars which are only driven on/off trailers. Use the NGK 6 or Denso 20 for normal use and NGK 7 or Denso 22 for aggressive street driving or occasional track use. When I owned "Barney", for the first few years I ran an NGK 6. From the late 90s to early 00s on I ran the Denso 20. The last couple of years I ran the Denso 22. Densos worked great in an LT5

2) I would not use plug readings as a basis for making decisions on long-term fuel trim, ie: BLM. First of all closed-loop operation likely does not color the plugs enough to offer useful information and secondly, pump gas has so many additives which erroneously color plugs such that whatever color you see is useless. That said, if you have a case where, say...six plugs are one color and two plugs are so black they are near-carbon-fouled, then you don't have a BLM problem you have an injector problem.

3) If you trust your O2Ses and don't have a wide band, ignore plug color and use the narrow band sensors. While I don't calibrate LT5s, I do calibrate various '96-up stuff and I strive to get ± 3% on part throttle, closed loop tuning of LTFTs. Trying to get closer than that and you'll just chase yourself into frustration...and waste a lot of time erasing and burning PROMs.

[XfireZ51]

Couple of comments here...

1) NGK 5 heat range is too hot for any LT5 other than show cars which are only driven on/off trailers. Use the NGK 6 or Denso 20 for normal use and NGK 7 or Denso 22 for aggressive street driving or occasional track use. When I owned "Barney", for the first few years I ran an NGK 6. From the late 90s to early 00s on I ran the Denso 20. The last couple of years I ran the Denso 22. Densos worked great in an LT5

2) I would not use plug readings as a basis for making decisions on long-term fuel trim, ie: BLM. First of all closed-loop operation likely does not color the plugs enough to offer useful information and secondly, pump gas has so many additives which erroneously color plugs such that whatever color you see is useless. That said, if you have a case where, say...six plugs are one color and two plugs are so black they are near-carbon-fouled, then you don't have a BLM problem you have an injector problem.

3) If you trust your O2Ses and don't have a wide band, ignore plug color and use the narrow band sensors. While I don't calibrate LT5s, I do calibrate various '96-up stuff and I strive to get ± 3% on part throttle, closed loop tuning of LTFTs. Trying to get closer than that and you'll just chase yourself into frustration...and waste a lot of time erasing and burning PROMs.

Thanks for the comments Hib. Appreciate u following this. I was using the NGK 5s based on the ground strap coloring. I’ve recently switched to the Autolite 3924 plug which has an extended nose relative to the NGKs. The extended nose actually is a “colder” plug than the 5 altho its about the same heat range. I can tell u the motor idled smoother and got measurably better mpg than the 5s. That could have been a function of the “new” plug, but the BKR5E-11s didn’t have more than 1k mi on them either.

I do use ZT-2 WB which is always in the car. So I watch that but only use the WB for WOT tune. I tune PT in C/L, so I datalog quite a bit, and agree that when shooting for BLMs I’m using a +/- 3 count window. So anything between 125-131 average is good. Of course the LT5 has the same issue as the LT1s did with right/left, Lean/Rich fuel distribution. Bigger cams tend to exacerbate that.

I do trust the O2s. They’re AC Delco, and they are new. Changed them out to make certain. Had ACs there to start. The cylinders I was concerned w mainly are 2&4 where the plugs were tending towards a shiny black, not sooty. That suggested oil to me, not injector. I did OHM the injectors, which of course is not conclusive but nothing overt was indicated. That’s why I decided to pop the top and look at the IHs and plenum. The pics I posted show oil surrounding the intake runner area and the trail leading back to the crankcase vents in the head.
Concurrently, I was also chasing a “random” knock issue at a steady cruise in the 1800-2200rpm range. Now I suspect the two issues are related, with oil seepage being the culprit for the knock.
However, as I posted earlier, I will be having injectors flow tested just because of the “while ur there” rule.

[Hib Halverson]

Even if you could read plugs accurately with today's pump gas, you'd absolutely not use the color of the side electrode as your benchmark. Also, you can't read plugs by driving around on the street mixed with WOT pulls.

To properly "read" plugs you need 1) a good spark plug viewing tool, 2) a fresh set of plugs, 3) a hard pull in third gear with a clean key-off (but NOT key-lock) at the top end and after you coast to a stop, pull some plugs and 4) look at the area down in the body of the plug...the insulator below the tip of the center electrode and the inside wall of the plug body. If you want to actually do that, you need to run some 100-oct unleaded race gas. That stuff will color plugs accurately.

You need to run a plug at least as cold as the NGK 6 or Denso 20 heat ranges.

As for data logging...I'm a little confused because you keep talking about BLMs. Are you tuning for part throttle closed loop or WOT open loop? If the latter, forget BLMs and use your WBO2S.

As for random detonation at part throttle...If you hear the engine rattling while it's in closed loop then either EST is f**ked-up somehow or your getting so much detonation, that KR is maxed. First thing to do is determine if what you hear is false knock or real detonation. The solutions to each are quite different. When the motor is rattling have you been logging data? If so, what is KR doing when that happens?

Spark plugs which look shiny black are from cylinders which are using oil and if the engine has some cylinders that are using enough for you to notice it shortly after a plug change, then there's a problem somewhere...as you apparently have decided.

Lastly, as you suggest, oil ingestion can cause detonation because oil is really low octane.

[XfireZ51]

Injectors are off to be checked. Meanwhile, I will be trimming IH gaskets and mounting on cylinder heads tomorrow. Then plenum gaskets go on to get trimmed if needed.
Installed new knock sensor from Rock Auto. Think I snagged the last one.

[XfireZ51]

Thx Hib,

Yes I’m datalogging because I do part throttle tuning in Closed Loop. So I use BLMs. Really can’t move onto WOT tuning until part throttle is nailed down. Besides, we spend 98% of our time in part throttle.
If u view prwvious posts u’ll see evidence of oil migrating from crankcase vents to intake runners.

[XfireZ51]

UPDATE:

IHs are bolted on. Waiting on injectors. Should hear something on them Monday/Tuesday. I did Permatex the crankcase vents on the cylinder head to stop oil migration under the gasket to intake runners. May be a PITA to scrape the gasket off next time but I’m hoping that’s a ways away.

[Ccmano]

Who’s testing your injectors? Local or did you have to send them off?
H
:cheers:

[XfireZ51]

Who’s testing your injectors? Local or did you have to send them off?
H
:cheers:

Sent them off to Portland. One of the people from ThirdGen has a shop.

[Ccmano]

Sent them off to Portland. One of the people from ThirdGen has a shop.

What do they charge if you don’t mind me asking?
H
:cheers:

[XfireZ51]

What do they charge if you don’t mind me asking?
H
:cheers:

Not sure they do it commercially Hans.

[WARP TEN]

Sent them off to Portland. One of the people from ThirdGen has a shop.

Doesn't Marc Haibeck do flow and electrical testing of fuel injectors? If it is the same sort of testing, Hans, there are prices listed on his webpage http://www.zr1specialist.com/ for the work. --Bob

[XfireZ51]

Bob,

I must admit, I never even thought of that. Actually nver recall Marc discussing this. Good to know, however. Hope this helps someone else.

[XfireZ51]

I got back a report on the injectors. I would say the “while you’re there rule” holds quite valid.

The #7 secondary injector basically sprayed a stream of fuel. This is due to plastic aerator in tip breaking down in the center. Bottom line is that after 10+ years this set of Accels is junk. At least 5 of them need to be replaced, but I run the risk of the aerator failure occurring in the other injectors at some point.
I just did this on a whim. Not really expecting this because after all, Accels don’t really break down. In my case at least, they have.

Here’s the email I got on the results

“Hey - so I tested all the injectors yesterday. The flow rates don't seem to be an issue, and all the injectors "function". However - 4 of the primary injectors have very poor spray patterns, and one of the secondary injectors has no spray pattern at all - it just fires a steady single stream. What has happened to these injectors is the plastic aerators in the tip that divide the flow into three equal streams have begun to disintegrate. and in the case of cylinder 7's secondary injector the center of the aerator has broken out and is essentially missing (gone through the engine I assume). I don't think this type of failure is repairable, and in any case I wouldn't want such a design with a plastic aerator that can fall apart and end up down the cylinder. Here is a picture of the failed aerator tip on 7S. I have videos of them in action also just have to figure out how to share them. It is my opinion that these are junk and I would replace them with a newer design. If you wanted to run them at least 5 of them need to be replaced due to spray pattern which from the plastic aerators either entirely or partially failed. Obviously cleaning them would do not good - in fact it may make some of them worse if it dislodges more of the brittle plastic tips.”

Attached is a pic of #7 secondary injector. If u recall, #7 is where I experienced a cracked compression ring last year.

[Top Toy]

Whoa! That's scary! Explains a lot! Now begs the question re whether or not your new rings or the cylinder have been damaged by unburnt fuel washing the oil off the cylinder wall. Do new Accel's have the same plastic tips?

[XfireZ51]

Dennis,

Glad u jumped in. I was going to ask u what ur using?
Don’t have answer on new Accels. Maybe someone else has info.

[Top Toy]

Dennis,

Glad u jumped in. I was going to ask u what ur using?
Don’t have answer on new Accels. Maybe someone else has info.

I've had FIC's for about three years. No issues yet (knock on wood!). I know some others have had drivability issues, though, so they're not fool proof.

[XfireZ51]

So now the question is which injectors to replace them with. Aerator for Accel is plastic and breaks down.
The RC Engineering are very expensive at $80/iinjector. I need 16. Ouch!
FIC Delphi (New) $729/ set
Southbay sells rebuilt Multecs at $329/set
Accels are $580 for the set.
Bosch III are the narrow body and won’t fit.

Talk about cascading failure.

[XfireZ51]

Was FIC able to provide the Voltage Bias for their injectors?

[tpepmeie]

I’ve run Bosch IIIs in my engine without problem. Granted that’s with 93-95 injector housings. Why do you think they won’t fit?


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[XfireZ51]

I’ve run Bosch IIIs in my engine without problem. Granted that’s with 93-95 injector housings. Why do you think they won’t fit?


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Todd,

I have the 90-92 IHs. The 93-95 IHs use injectors that all seal at the tip like the secondaries do on the 90-92 IHs. I need injectors that also need to seal using the Oring in the IH secondary injector boss groove. The Bosch IIIs are narrow body injectors.
Currently thinking about either the Delphi units or trying to determine if Accel has changed the design of their injectors to eliminate the plastic aerator. My injectors are 10+ years old.

Bosch IIIs v Delphi units for 90-92 IHs.

[Ccmano]

I assume you’ve looked here for compatibility. Ford and Bosch/Ford injectors come in 22lb versions and they fit.

http://users.erols.com/srweiss/tableifc.htm

H
:cheers:

[Jagdpanzer]

With the Bosch III form looks like any dimensional compatibility issues could be easily solved with specially machined sleeve bushings for the primary injectors.


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[tpepmeie]

That would be excellent. They really are a fantastic choice. The design IV are similar form factor, and even better. But the full specs are not usually available. The IIIs in most cases have Ford motorsports specs published, one just needs to convert the specs from Ford to GM, which is not trivial.


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[-=Jeff=-]

I still have my FIC rebuilts.. 10 years

[XfireZ51]

With the Bosch III form looks like any dimensional compatibility issues could be easily solved with specially machined sleeve bushings for the primary injectors.


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Phil,

Actually I investigated this w both Southbay and FIC. There is a sleeve that is used for the Bosch IIIs on L98s which they both provide. However, they both told me it would not work for the 90-92 IH due to the need to seal the primary injector w the O ring in the primary injector boss. It will work for the 93-95 IHs as Todd or Jeff are using.
So I decided to go w the new Delphi injectors which, based on FIC pricing, are competitive w the Accels. I tend to lean towards use of OEM level quality rather than aftermarket. They’ll also be providing me w “deadtime” values to be used in the Voltage Bias tables. And I appreciate that the injector set will have been flow matched to +/- 1%. That provides additional value for me.
Here’s the video FIC posted regarding modifying Bosch IIIs for the L98.

https://youtu.be/XaYtP4l5A_4

Here’s FIC discussing use of Bosch IIIs for 90-92 IHs

https://youtu.be/OABElyDRicU

[Karl]

Dennis,

Glad u jumped in. I was going to ask u what ur using?
Don’t have answer on new Accels. Maybe someone else has info.

If you zoom in on the tip of these new Accell injections in this thread the tip looks the same.

http://www.zr1.net/forum/showthread.php?t=29954&page=2

[Top Toy]

Re the voltage bias, I assume you're referring to the pulse width correction vs. supply voltage? I did not get anything from FIC and am still using the stock table. Have you seen significant differences with other injectors?

[XfireZ51]

Re the voltage bias, I assume you're referring to the pulse width correction vs. supply voltage? I did not get anything from FIC and am still using the stock table. Have you seen significant differences with other injectors?

Dennis,

I requested the Bias values from FIC and was told initially I didn’t them and to just use stock values. I’m from the school that says the info going into the ECM NEEDS to be correct in order to get the most accurate tune. I did this w the Accels and the VE tables were different for conditions such as Decel, Idle and low speed part throttle where the Bias plays a bigger role in the PW calc. I can let u know when I get them.

[Top Toy]

Yes, I'll be very interested in what you learn. It's apparent from the table that if the values don't match the actual bias of the injectors that it would really screw up a good tune!

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[XfireZ51]

Yes, I'll be very interested in what you learn. It's apparent from the table that if the values don't match the actual bias of the injectors that it would really screw up a good tune!

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Dennis,

Since the Bias value is a curve representing bias values at various voltages, it represents a significant portion of the PW calc when PW is small. That occurs during situations such as idle, decel, and trailing throttle as examples. The Voltage Bias is meant to compensate for votage change that happen when u turn on headlights, fans kick on, A/C operation, turn signals. A motor that seems to run and idle fine, runs like crap when it gets hot. U can try to fudge the VE tables but that only represent an ideal situation and doesn’t address all conditions which is a requirement for driveability, emissions and economy. And the values can be all over the board when it comes to injectors and manufacturers. And the values change based on fuel pressure variations. So its not as easy as just “slapping” in a new set of injectors. If u do that and datalog, u’ll find the VE tables changing. In the case of a modded motor, particurlarly w cams, it is one of the contributing factors to better controlling idle. Other tuners that I have great respect for, won’t tune a motor without those values.

[tpepmeie]

That’s why I use the Bosch/ford Motorsport injectors. All the info is available. Injector dynamics likewise, but theirs are too big for our applications. Fuel injector clinic has some 35s which they provide specs for. Still probably too big for all but the biggest motors.


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[XfireZ51]

That’s why I use the Bosch/ford Motorsport injectors. All the info is available. Injector dynamics likewise, but theirs are too big for our applications. Fuel injector clinic has some 35s which they provide specs for. Still probably too big for all but the biggest motors.


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Todd,

I’ll let u guys know if I get them. I think we may have identified these injectors as the Delphi FJ 10024 which is spec’d for the 89-91 L98. Should know more by Monday when they arrive from FIC. Hans says they’re rated at 22# at 43.5psi.
Accel was never forthcoming w their info on the 150121. I had someone test them to get the Bias values.

[Top Toy]

All makes perfect sense. Thanks for keeping is posted!

[Ccmano]

Todd,

I’ll let u guys know if I get them. I think we may have identified these injectors as the Delphi FJ 10024 which is spec’d for the 89-91 L98. Should know more by Monday when they arrive from FIC. Hans says they’re rated at 22# at 43.5psi.
Accel was never forthcoming w their info on the 150121. I had someone test them to get the Bias values.

Actually I think the ones your getting are Standard Products FJ47T’s likely made by Delphi (or the other way round). I haven’t been able to find a Delphi number but I do believe they carry a code 01D180B printed on the side. They may even be Lucas produced as Lucas injectors use a similar coding. I’ve seen them advertised as 22lbs but have not been able to find actual specs. Have you asked FIC what they are and what the specs are? I know they advertise them as Delphi.
H
: cheers:
http://a64.tinypic.com/2lwvd3l.jpg

[XfireZ51]

Hans,

Could be because the pic u posted looks like the one on the FIC website for the LT5 injectors compared to the L98 injector.
The first one is of the FIC LT5 injectors while the second is the L98. And I think u are correct that these are Lucas or Lucas style injectors.

[Ccmano]

This one was advertised as Dephi 22lb/hr injector. Note the code on the side.
01D180B....
H
: cheers:

http://a68.tinypic.com/v786qa.jpg

[XfireZ51]

Injectiors arrived today from FIC. And they confirm what Hans speculated regarding which injector they are.
FIC shows them as flowing 21.5# at 43.5psi. The Accels I had tested flowed 21# at 3 bar. If this holds, I may need to tweak VE tables or I could try bumping Injector Constant a notch. Probably more significant than that is that the VE tables have been tuned to the Accel injectors I had which were deteriorating. And the car ran pretty well as it was. Marc Haibeck had a chance to drive my ZR from lunch one day, and he commented on how it ran well and accelerated smoothly. So now we’ll see what happens when u have all 16 injectors working.😉😂
One other difference between this and the Accel is that the aerator on the Delphis is recessed in the tip. As u can see from an earlier post, the Accel aerator is exposed at the end of the tip. I wonder if Delphi recesses the aerator to shield it.

[XfireZ51]

Here’s the difference in the aerator position between the Accels and the Delphis

The Delphi aerator is recessed quite a bit into the tip, while the Accel is exposed at the end. How that affects spray pattern I can’t speculate on.

[Top Toy]

Do you expect to have any luck getting the bias table for the FIC's? Better hurry up and get them in before the snow flies!

[XfireZ51]

Dennis,

I was told I would have them. Now that I have injectors, I’ll be calling tomorrow to get them.

[XfireZ51]

The people who checked my injectors were good enough to video the several of the injectors including the #7Secondary which had the disintegrated aerator. At first I thought there was no fuel coming from that injector. There is but u can’t see it.
BTW, #7 was the cylinder that had a compression ring broken in 4 parts which
Dr. Greekenstein then repaired. Coincidence?


https://youtu.be/xEvvtr84c8k

[Top Toy]

Very interesting, though, that when the foam settled, the amount of liquid delivered by no. 7 was the same as the others. No. 7 just atomized a lot more than the others. That may have been your best injector!

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[XfireZ51]

Very interesting, though, that when the foam settled, the amount of liquid delivered by no. 7 was the same as the others. No. 7 just atomized a lot more than the others. That may have been your best injector!

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Dennis,

What u could not see in the video is that the fuel was not atomized. Here’s what the tech said about that injector
“Yeah you can't make out the stream very well. It's solid fuel.” Solid fuel won’t ignite and so that cylinder was running lean. That is verified by looking at the spark plug. Which would explain the busted compression ring earlier. According to the tech, it was squirting like a firehose which explains the frothing. This would also explain the knock I was seeing. He also explained why I would see knock at part throttle but not at WOT.
At lower rpms, the injector is the primary means of atomizing the fuel. At WOT, the higher air velocity thru the runner shears the fuel, much like how the TBI system worked, and so the atomization was achieved in that manner.

[XfireZ51]

Motor is about ready to fire up tomorrow. Just need to torque down plenum bolts.

[XfireZ51]

Motor fired up and idled well today. I can't make any statement about the Accels v the Delphis given the state of the Accel injectors.
Looking forward to doing some datalogging to see what difference this makes.
I have new plugs in the motor so I should have some indication of mixture control. The FIC injectors are rated at 21.5#/hr and are a matched set. We'll see the advantages flow matched injectors provide.

[Top Toy]

Congrats on the speedy recovery! Hope you don't have to do too much retuning.

[XfireZ51]

Perhaps getting into the weeds a bit for some, but when u get Injector Voltage Bias from injector providers, u may not get the values for the voltages specified in the calibration. So u need to do interpolation. I found this utube vid to be very helpful.
This is not specific to Voltage Bias and is helpful for any form of interpolation u may need.

https://youtu.be/w-mbjyA9jxE

[Top Toy]

Did you get the FIC bias table?

[XfireZ51]

I got the Accel injectors back from testing yesterday. Only the #7secondary had an aerator that was disintegrated. However, the process of disintegrating progresses from behind the aerator which is exposed to the injector’s high pressure fuel stream. So basically, it wears away over time until there’s nothing left in the middle of the aerator. Altho #7S showed that, it eventually would demonstrate itself in the other injectors.

[XfireZ51]

Here's a graphic representation of the difference between stock, Accel and Delphi injectors re: voltage bias. Clearly the Delphis are " faster" reacting than either the Accels or the Stock injectors.
BTW, the volts on the X axis, is not the actual Voltage value. The graph is simply meant to demonstrate the difference in the injector latency between stock, my current Accels, and the Delphis I recently installed. The Delphis are nearly 2x of the Accels. The implication here is that especially at low PW conditions, the voltage bias plays a significant role in the overall PW calc. Getting it right makes a difference in developing a proper tune.

[XfireZ51]

Today was a good day to take the car out for the first time after having put things together. Had the opportunity to do some datalogging.
The FIC injectors are rated at 21.5# while the Accels rate at 21#. So my expectation was to see richer BLMs, but in fact, the BLMs demonstrated an overall lean condition. Next step is to check the spark plugs for confirming evidence of this.
However, one issue that appears to have been resolved is knock counts at cruise. Driving for 20 minutes or so at 1800-2000rpm did not result in additional knock counts, unlike previous. I will start to “bump” timing in this area to determine how much more timing can be used here.

[Ccmano]

Good to hear. Looks like the reseal of the IH’s did the trick and stopped the oil injection. Any difference in idle smoothness with the new injectors?
H
:cheers:

[XfireZ51]

Good to hear. Looks like the reseal of the IH’s did the trick and stopped the oil injection. Any difference in idle smoothness with the new injectors?
H
:cheers:

On the basis of SOTP, yes idle feels smoother, but looking at the log, it needs tuning. Large areas of the VE tables need modifying because it is running lean. However, the motor, again, feels more responsive and quieter at cruise.
It’ll be warmer here tomorrow, so I’ll have a chance to do some datalogging on a new tune. I’ll pull a couple of plugs tomorrow just to corroborate the lean indication from the datalog.
I can “induce” knock counts by stabbing the throttle and backing off. But that could be the trans in combination w a SM flywheel. Mashing the throttle, I don’t get counts just tires spinning.

[XfireZ51]

Ok, the next datalog shows an overall rich condition. Pretty typical pattern u get when tuning. U get swings back and forth but the narrowing the BLM window until its close enough, ie +/- 3 counts. So anywhere from 125-131 BLM as an average.
The basic relationship between left and right banks has not changed. Right is the on the rich side, while left is lean. The first tune appeared to make the motor run smoother. The next tune will have smaller increments of change both lean and rich.

Below are pics of the #2 cylinder plug w right side being previous to upgrade of injectors, left after first datalog.

[Ccmano]

I suspect that difference in the plugs is more fixing the IH oil leak than the injector change.
H
:cheers:

[XfireZ51]

I suspect that difference in the plugs is more fixing the IH oil leak than the injector change.
H
:cheers:

Hans,

On this particular cylinder, #2, I would agree w you. #7 on the other hand, had indications of more normal combustion rather than lean as it was. That would point towards the injector swap affecting fuel mixture.

Also regarding knock, I decided to roll back timing to utilize the stock table in the area of the SA table where I encountered knock occurring. I believe this area of the SA table is a critical one for eliminating knock because the motor spends quite a bit of its operating time in this area. After rolling back to stock timing, it essentially eliminated knock from occurring. I may decide to bump it a couple of degrees to test the boundaries, but I'm not certain that it would make much difference relative to the overall performance at those points.

[XfireZ51]

Happy Holidays to everyone. I believe we are getting close to wrapping this up.
I pulled plenum to check out coils, primary and secondary windings. All tested fine. Checked plug wires as well. Fine.
Since the plenum was off, I decided to check it for "flatness". Plenum was warped. Straightedge rocked by about .020". Spoke w Dr. Greekenstein (aka Pete). He told me that most plenums have some warpage to them. Suggested silicone gasket around the ports. I used Blue RTV since it is safe for O2 sensors.
Silicone gasket maker can kill an O2 sensor by contaminating it.
Finished installing plenum and took it out for a spin and logging session.
The difference was pretty clear from idle all the way thru. The BLM split was much tighter now w both right and left sides converging closer. Right was still richer than left but now the diff in BLMs was 124-132 or an average of 130 which is close enough. Idle was much more stable @ 925-950rpm and pulling about 48kPa which is pretty good considering Pete's cams.
Also, no knock counts. So I can start inching SA up a bit to see how close I can "tickle" the knock sensor.
So this wasn't The Silver Bullet. BUT, it was one of the pieces of the puzzle.

To summarize so far:

1. Broken injector, poor spray pattern and deteriorated aerator(s)

2. Oil seepage from crankcase vents into combustion chamber.

3. Warped plenum allowing additional air into fuel flow.

All of this points to areas that we probably take for granted when we have our motors apart. Should add these to the list of things to check when doing a plenum pull. It also goes to prove, before any tuning, its important to verify that all components are operating at nominal levels, otherwise tuning is like a dog chasing its tail.
This also suggest that you verify the datalogging measurements with some good old fashioned "eyes on" the motor. The car was running well. I believe had you driven the car. you would not suspect the issues that have been uncovered. Marc thought the car ran well when he drove it several weeks ago before I started this rehab. But had I brought it to a dyno, I likely would have been disappointed.

The datalog I just recorded shows some additional tweaking needed as expected. But not to the extent previous. I know I'll be re-checking torque on plenum after a few heat cycles.

[Top Toy]

Congratulations Dom! Thanks for sharing everything you've learned along the way with the rest of us! Wishing you many happy miles in 2019!

[XfireZ51]

Congratulations Dom! Thanks for sharing everything you've learned along the way with the rest of us! Wishing you many happy miles in 2019!

Thanks Dennis. I really won’t be able to confirm until weather gets warmer out there. I think I’ll try a set of iridium plugs next.