Injectors - Advice

[Dafink]

OK, I'm going to undertake replacing the injectors. Does anyone have any words of wisdom before I start?

I am thinking of using these injectors -

http://www.ebay.com/itm/Chevy-Corvette-ZR1-1990-1992-Flow-Matched-Fuel-Injectors-/121088079341?hash=item1c316975ed:g:lakAAOxy14VRVli B&vxp=mtr

or -

https://www.summitracing.com/parts/acc-150821

Anyone have any experience? Also any resources or tips are appreciated.

[A26B]

First, how can an injector be reconditioned? Maybe cleaned & tested constitutes "reconditioned".
FIC, a supporting vendor of the ZR-1 Net, "used" to offer "reconditioned" injectors, but no more. Reconditioned injectors are a hit & miss proposition. I recommend you avoid the eBay reconditioned injectors.
I do recommend FIC new, stainless steel injectors for the value and certainly for their customer service.

The Accel injectors also have a good track record, as does FIC. The last I knew, the Accel injectors required trimming the connector lock tab to install. Someone here with first-hand knowledge can verify that for you

[Arctic91]

I have installed Accel injectors (part number ACC-150821) in each of my cars, and have had no issues. I installed them in my 1991 about 9 yrs ago and installed them in my 1990 just last month.

A26B is right... a small alignment tab on the housings of primary injectors will need to be removed with a grinder. Very easy and it just takes a couple of mins to do all eight. I bought mine from Summit, and they seem to always have good prices.

Here's an article from Mark Haibeck's site, which should give you some additional details: http://zr1specialist.com/HAT%20Web/articles/Fuel%20Injector%20Replacement.pdf

Scott

[XfireZ51]

Accels continue to work flawlessly after 8 years.

[5ABI VT]

I cant recall if it was RC that had them on special last year when I needed o rings. Im kicking myself for not getting them then but Im wanting to replace mine soon too. :happy1:

[ZRXMAX]

I am coming up on 10 years with Accels and roughly 70K miles of service. The price was $526 from Summit for 16 when I bought mine if memory serves me right

[Dafink]

Did you need to cut/modify the Accels?

[XfireZ51]

Did you need to cut/modify the Accels?

There's just an extra tab on the injector that is not necessary for installation. You can grind it or cut it off to install the harness connector. No issues otherwise.

[Kevin]

fuelinjectorconnection.com discount and lifetime warranty for registry members

[RussMcB]

fuelinjectorconnection.com discount and lifetime warranty for registry membersThese are the ones I went with last year. I'm happy with how my car is running.

[Paul Workman]

fuelinjectorconnection.com discount and lifetime warranty for registry members

And, they come as a kit that includes Jerry's Gaskets "O-rings" and plenum gaskets too that one will need to do the replacement, if I recall correctly. A discount and a lifetime warranty...hard to beat that!:):cheers:

[Johnny5]

definitely get new, when you see how much work is involved you will only want to do it ONCE. FIC stainless steel, ask Jerry or FIC.

[Dafink]

OK so I completed my injector project, used the Accels. Took the car out all last night and it runs like a champ now. Took the opportunity to swap out all coil packs as well. I have not put the plenum back on with finality yet as I wanted to make sure there was nothing left to do in there. I will be ordering the gaskets and swapping all the plugs.

My rough idle and access to secondary power is now there. The job was surprisingly easy (with help from a friend who is adept at engine work), the toughest part seemed to be getting the plenum back on safely and properly.

[Roadster]

OK so I completed my injector project, used the Accels. Took the car out all last night and it runs like a champ now. Took the opportunity to swap out all coil packs as well. I have not put the plenum back on with finality yet as I wanted to make sure there was nothing left to do in there. I will be ordering the gaskets and swapping all the plugs.

My rough idle and access to secondary power is now there. The job was surprisingly easy (with help from a friend who is adept at engine work), the toughest part seemed to be getting the plenum back on safely and properly.

Always good to hear a success story, glad they worked out for you. Will be doing my first plenum pull sometime in the future, want to make sure I have everything that is needed.

Does anyone know if FIC offers us the discount year round? As I remember last year near the holidays they were offering a very good deal.
Thanks for any info......

Also, I know this has been discussed before, but what is the correct lbs/hr for the LT5???

[secondchance]

Always good to hear a success story, glad they worked out for you. Will be doing my first plenum pull sometime in the future, want to make sure I have everything that is needed.

Does anyone know if FIC offers us the discount year round? As I remember last year near the holidays they were offering a very good deal.
Thanks for any info......

Also, I know this has been discussed before, but what is the correct lbs/hr for the LT5???

Tom,

Lbs rating varies depending on fuel pressure. Accel injectors are rated at 21 lbs at 42psi (I think...).
After all that work yesterday, I must have installed bad injector when replacing what I thought was weak secondary injectors. As secondaries open up I feel light vibration and engine doesn't feel as strong as it should.
I just ordered a set of Accels.

[Roadster]

Tom,

Lbs rating varies depending on fuel pressure. Accel injectors are rated at 21 lbs at 42psi (I think...).
After all that work yesterday, I must have installed bad injector when replacing what I thought was weak secondary injectors. As secondaries open up I feel light vibration and engine doesn't feel as strong as it should.
I just ordered a set of Accels.

Yun,

I guess you weren't to happy about that.....we had the good and the bad separated....hmmmm
Don't know when you will be replacing them again....I will be happy to assist once again, if needed. Won't be available Wed-Thurs-Fri, but Sat or Sun looks good so far. Just let me know....
So far it seems like people who are using the Accels are very satisfied with them, from what I have been reading. At least the coolant doesn't have to be drained.........:-D
Maybe think about new "o" rings with this installation, even though the others looked good...

[secondchance]

Yun,

I guess you weren't to happy about that.....we had the good and the bad separated....hmmmm
Don't know when you will be replacing them again....I will be happy to assist once again, if needed. Won't be available Wed-Thurs-Fri, but Sat or Sun looks good so far. Just let me know....
So far it seems like people who are using the Accels are very satisfied with them, from what I have been reading. At least the coolant doesn't have to be drained.........:-D
Maybe think about new "o" rings with this installation, even though the others looked good...

No worries... Comes with the territory.

[Scrrem]

After all that work yesterday, I must have installed bad injector when replacing what I thought was weak secondary injectors. As secondaries open up I feel light vibration and engine doesn't feel as strong as it should.
I just ordered a set of Accels.

Yun,
Are you absolutely certain it's an injector? I have had a persistent stumble on the new motor under WOT and some times on high RPM deceleration with throttle closed. I believe it may be a chip issue. Did the symptom change a from the injector change?
Rich

[GOLDCYLON]

Yun,
Are you absolutely certain it's an injector? I have had a persistent stumble on the new motor under WOT and some times on high RPM deceleration with throttle closed. I believe it may be a chip issue. Did the symptom change a from the injector change?
Rich

Rich that Must a chip issue I don't have that with my 380. Did you have Dom look at and do your cal?

[Scrrem]

Rich that Must a chip issue I don't have that with my 380. Did you have Dom look at and do your cal?

No, I may have him take a look over the winter It's Mark's chip and the car has had this issue since I put the newly calibrated chip in. I really noticed it bad on the mountain run.
Rich

[GOLDCYLON]

No, I may have him take a look over the winter It's Mark's chip and the car has had this issue since I put the newly calibrated chip in. I really noticed it bad on the mountain run.
Rich

He has my 380 cal on file it might be worth a shot. It took a few swaps via the mail but I'm sure I am running the 90% solution

[secondchance]

Yun,
Are you absolutely certain it's an injector? I have had a persistent stumble on the new motor under WOT and some times on high RPM deceleration with throttle closed. I believe it may be a chip issue. Did the symptom change a from the injector change?
Rich

Yes. Issue was rough idle at first. Picked up 8 FIC Bosch rebuilt injectors from Phil. These new ones were installed for primaries. Removed primaries with high ohms were used to replace 3 secondaries with relatively low ohms. Now, engine developed loss of power and vibration as secondaries come on line. So much for resistance testing for injectors...

Either way, I want to rule out injector issue 100% first. FIC had posted that they found out these Bosch rebuilds we're shorting out and decided to drop the line. Hopefully, once I pop in Accels car would be back to what I remember.

[XfireZ51]

Schance,

I assume u r not getting a code? Usually loss of power and engine shudder comes from secondaries not coming on. Are you mix and matching injectors or are the all one type?

[secondchance]

Schance,

I assume u r not getting a code? Usually loss of power and engine shudder comes from secondaries not coming on. Are you mix and matching injectors or are the all one type?

I'm not getting any code - not yet anyway. I have been running FIC Bosch rebuilt units since 2009. Recently idle was so rough dual mass flywheel was making a racket. So, I replaced 8 primaries with new Bosch rebuilt injectors and replaced possible border line secondaries with what I assumed to be better injectors removed from primaries (all Bosch) - wrong! Now, she shudders as secondaries come on line. BTW - I have secondary delete so, I believe, secondaries come online at 5% throttle (if I remember correct...).

[tpepmeie]

My $0.02... Many times "the chip" is blamed for issues which are actually mechanical in nature. Marc's basic calibrations are tried and tested over hundred's of cars, so I would be more inclined to suspect a mechanical root cause.

Your statement that you swapped the old primaries into the secondary position grabbed my attention. I'd suspect a potential problem there. Did you check the resistance of the now secondary injectors? Apologies if I missed that earlier. Does the symptom manifest cold as well as fully warmed up?

[tpepmeie]

As a more general follow-up to the title of this thread, I have become very fond of the Bosch / Ford Motorsport injectors. These are the newer EV6-style, longer and skinny. There are 24 lb/hr versions, as well as 30 lbs, 16 of which are more than enough for 800 hp.

Why do I like these? First, they are a direct fit. A more modern design than the Accels or Multecs. And most importantly the full injector characterization is available from Ford (voltage and pw offsets), although it has to be translated to GM's method.

The 24 lbs'ers are the "LU24A" variety. The 30's are BB302's. From what I have seen, they are linear at very low pulsewidths so even the 24's should be ok for a lightly modified engine. Ford's flow rating is at 39.15 psi, so the 24's flow like 27's at LT5 rail pressure.

Contact me offline if you want more info.

[secondchance]

My $0.02... Many times "the chip" is blamed for issues which are actually mechanical in nature. Marc's basic calibrations are tried and tested over hundred's of cars, so I would be more inclined to suspect a mechanical root cause.

Your statement that you swapped the old primaries into the secondary position grabbed my attention. I'd suspect a potential problem there. Did you check the resistance of the now secondary injectors? Apologies if I missed that earlier. Does the symptom manifest cold as well as fully warmed up?

Old injectors - I believe they were still warm (about 70-80 degrees) by the time plenum was removed - all registered 15.3 to 15.5 ohms. New ones - cold at about 55 to 60 degrees - all measured around 14.6 - 14.7 ohms. I assumed ohm difference was due to temperature. Engine vibration showed up almost as soon as I drove away from Jim's garage so symptom showed up when cold and stayed when fully warmed up. What do you think Todd? Seriously mis-matched injectors?

[XfireZ51]

I'm not getting any code - not yet anyway. I have been running FIC Bosch rebuilt units since 2009. Recently idle was so rough dual mass flywheel was making a racket. So, I replaced 8 primaries with new Bosch rebuilt injectors and replaced possible border line secondaries with what I assumed to be better injectors removed from primaries (all Bosch) - wrong! Now, she shudders as secondaries come on line. BTW - I have secondary delete so, I believe, secondaries come online at 5% throttle (if I remember correct...).

I'm sure that w Marc's chip the secondaries come on-line right off idle.

[Roadster]

I'm sure that w Marc's chip the secondaries come on-line right off idle.

The content below is from my conversation with Tim Holland back in 2014 after I purchased my ZR-1. I thought it would a good read here with the injector conversation.......
In case you would like to read the thread, here is the link....
http://www.zr1.net/forum/showthread.php?t=22910


Re: My recent phone conversion with Tim Holland GM/LOTUS Engineer for the LT5....

more info from the call......the following may have already been discussed over the years, and known by many, but I thought it would be interesting to mentioned what we talked about now, some 20 years later.

...The LT5 was on the dyno for at least 400 hours, GM's dyno testing was very aggressive at the time.
...The LT5 ran hotter than usual at the time. (I imagine he was comparing the LT5 to the other engines of that time period)
...When I asked him about the PROM chips available from the aftermarket, such as Marc's and others, especially with the fans coming on at lower speeds, he said that the oil needs to be @ 88 degrees centigrade,
(which is 190.4 degrees F) in order for the oil to boil out the condensation in the engine. He said you don't want to run these engines at like 150 F, as it would do more harm than good. Even with the fan temps from the aftermarket PROM chips, I think we are ok, JMO.
And he also mentioned if doing a lot of short trips, to make sure you get up to operating temp. There is also a thermostat in the oil line.
...a twin roller chain was added for the cams, as they seemed to have a problem with the earlier single roller chain. (hope I understood him correctly on this one).
....make sure you are warmed up at operating temp before doing any WOT's.


the remaining part of our conversation......

...engine is more fuel efficient on all 16 injectors open rather than just 8 injectors.
...talking about the "tube" going from the rear of the trans to the axle,(I imagine the "tube" he was referring to is the driveshaft. Mentioned that when accelerating that you should be smooth with power delivery, and not jerk the engine in gear, such as accelerating in 1st gear, letting off, than accelerating again in same gear (jerking). This puts undo stress on the bolts that connect the joint at the back of the trans, which can come loose from that motion (think I understood him on that) which can sag when applying torque and therefore result in the gear lever (shifter) moving upwards when accelerating. This is a machined part and needs to be exact. Apparently this was discovered during testing, thus resulting in using a smooth delivery rather than a jerking power delivery.
...secondary injectors opening is based on fast you are going and not a specific RPM.
...clutch reservoir contains the "black cup" as I refer to as.....which purpose is to prevent air and moisture from entering the system. That "black cup" should be collapsible to underneath the cap, mine isn't. But not to run without one.
...also spoke about changing out the anti-freeze fluid in the engine. I mentioned about the Dex-Cool may create complication on the gaskets, he said he was not aware of that, but also mentioned that he has been out of the "circle" for a number of years. When I said about filling the system and not getting any air pockets, he said that there are bleeder pipes on top of the plenum (he thought between #2 & 3 and #4 & 5 cylinders). The fill cap was placed on the highest point of the engine for a purpose. He also mentioned that when filling the system, that it will purge itself.

My thought is.....Of course alot more has been learned about the LT5 since the production years and different ways to maintain and prevent any possible complications that may arise.

That was about the content of our conversation from all of the above posts, interesting to say the least, especially for me, as I am still in the learning process of the LT5 and the ZR-1 overall.
Glad I could share with you.......thanks for looking...


ok some clarification on the subject......I had mentioned to Tim that it was recommended to bring the r's up to 7k in first and second gear to make sure that the secondaries would open and that the engine was running good. From what I remember and took notes on, he mentioned that the opening of the secondaries were based on the speed of the vehicle and not a specific RPM to where they open. The following is my thoughts....Obviously when you hit a certain RPM in an aggressive start, the vehicle is traveling at a certain rate of speed. I would imagine that traveling at a highway speed and a certain rpm range that is less than an aggressive acceleratioin and rpm range from a start would still open the secondaries as speed increases.
Again, I have nowhere near the knowledge that this forum has, and just thinking logically out loud. I intend to contact Tim in the near future, and will make sure to ask him to explain this once again. I was trying to get in as much as I could during our conversation and doing "shorthand"...lol
Wish I had the conversation taped........

[Paul Workman]

I'm sure that w Marc's chip the secondaries come on-line right off idle.

That is true, according to Marc, in the context of his SECONDARY DELETE calibration ONLY- if that is what is being discussed.

Op: For clarification, the secondaries are triggered ON based on rpm AND throttle position and operating temp - all three being considered.*

*Except for the secondary deleted calibration where the secondaries come on just off of idle. At that point the pulse width is split between two injectors, thus maintaining proper AF ratio.

An excellent source for information is contained in: "Corvette Fuel Injection and Electronic Engine Management" by Charles O. Probst, ISBN: 0-8376-0861-9 by BENTLY Publishing.

It contains excellent diagrams, schematics, charts and technical details in a well written and easy to understand style. It is an excellent read, especially for anyone that just bought a ZR-1, or for someone just needing to brush up on his knowledge and troubleshooting.

[XfireZ51]

Paul,

My comment was ONLY directed to the Secondary Delete calibration.

[Hog]

Here is a diagram of the EV6 injectors talked about earlier compared to older EV1 injectors. I run the EV6 with USCAR connectors, they came in some GEN 3/4 SBC applications (LS2). They are 24 lb/hr @ 43.5psi (3BAR) test pressure. The LT5 rail pressure is 50.7psi.

http://bertok.us/pics/l31marine/4/diag1.jpg

[secondchance]

16 new Accel injectors showed up yesterday. Got home at 3 pm today. It was 3:45 when I started. Replaced 16 injectors and got everything buttoned up by 6. Not bad!
I'll report back after I get a chance to test drive. Right now, too much evening rush hour traffic.

[PhillipsLT5]

no buyer remorse with accels

[secondchance]

Drove out to Katie's cars & coffee, met up with Phil, Rich and Scott - a new ZR-1 owner.
Noise I was hearing definitely was due to one or possibly more primary injector going bad. LT5 ran beautifully. It took me twice but finally got it right.

[Paul Workman]

Paul,

My comment was ONLY directed to the Secondary Delete calibration.

Yes, and accurately so. But, to the unfamiliar - nobody in particular - it struck me that the secondary-delete nuance might not be clear to some...was my point (hence directed to the "OP" ;))

[Starman]

This site used to recommend the RC stainless injectors. Installed about 8 years ago, no more stumble. Not as cheap as the Accel, but flow matched.

[rkreigh]

I just replaced the injectors on the LSV and went with the FIC stainless. Flow matched, great price, and the car runs smoother and more powerful than ever!

Thanks to Demps for helping me out. I had a throttle shaft plug pop out and then a couple weeks later another one. They have been fine ever since the conversion but for some reason now popping out.

Demps took care of it even though it wasn't his fault

Standup guy who does really great work.

[Dynomite]

This site used to recommend the RC stainless injectors. Installed about 8 years ago, no more stumble. Not as cheap as the Accel, but flow matched.

I use RC SL4-205 injectors (500+ hp). Tech Info - LT5 RC SL4-205 injectors (500+ hp) Calculations (http://forums.corvetteforum.com/c4-zr-1-discussion/3117790-tech-info-lt5-zr-1-technical-calculations.html#post1581660578")