Secondary relay module questions

[-=Jeff=-]

There is a post on CF as well, but I had some questions regarding the module.

in that other post, someone said the module was used 90-92 and 93-95 did no and it was in the ECM.. since the replacement ECM is the same for all years (although Kurt's website only states 90-94) then couldn't the module be eliminated and the wiring/harness/ PROM be made to work without the Relay module?

I am trying to understand the logic, if the 90 has the module, but I use a ECM that can be used in a 93 in my 90 and it works, I would think you could change something to eliminate the relay module if needed.


Now I could be all wrong ont he relay module as I am going by what I read in another post..

[lbszr]

I heard and thought the same thing :icon_scra http://www.zr1netregistry.com/forum/showthread.php?t=5565

[-=Jeff=-]

I heard and thought the same thing :icon_scra http://www.zr1netregistry.com/forum/showthread.php?t=5565

THANKS!!!

Now THAT makes sense.. it was not eliminated just moved.. LOL

[65ZR1]

The secondary injector modules were used for all years. However, the 90 model had a seperate knock module that was later integrated with the ECM. When I had a custom harness made for my 94 LT5 to allow it to run in a 65 coupe the company eliminated the modules and used a relay. They said it would work fine. This appears to make sense since the modules seem to be just an on/off switch. The pulse of the secondary injector is still controlled by the primary injector ground circuit though the ECM. I wasnt confident enough to try this route since I thought the general must have used a more expensive module for some reason. I guess when we cant find any then someone will give it a shot!

[lbszr]

The secondary injector modules were used for all years. However, the 90 model had a seperate knock module that was later integrated with the ECM. When I had a custom harness made for my 94 LT5 to allow it to run in a 65 coupe the company eliminated the modules and used a relay. They said it would work fine. This appears to make sense since the modules seem to be just an on/off switch. The pulse of the secondary injector is still controlled by the primary injector ground circuit though the ECM. I wasnt confident enough to try this route since I thought the general must have used a more expensive module for some reason. I guess when we cant find any then someone will give it a shot!


Who made your harness? Might need to figure out a different ignition system someday also.

[XfireZ51]

Who made your harness? Might need to figure out a different ignition system someday also.

It would be interesting to adapt the LS coil packs to the LT-5. Some people suggest that the coil packs along with the short plug wires account for 25+ hp.

[-=Jeff=-]

It would be interesting to adapt the LS coil packs to the LT-5. Some people suggest that the coil packs along with the short plug wires account for 25+ hp.

Yeah but if i did that kind of conversion I would install the coil packs under the plenum still..

I need to ook at the wiring but I bet it can be done.. depnding on the signal off of the crank sensor

[Aurora40]

Some people suggest that the coil packs along with the short plug wires account for 25+ hp.
Seriously? How do they account for such a suggestion?

FWIW, the Northstar went from coil packs to coil-on-plug (much more on-plug than the LSx) for the 2000MY. There was no huge power gain from that.

[XfireZ51]

Seriously? How do they account for such a suggestion?

FWIW, the Northstar went from coil packs to coil-on-plug (much more on-plug than the LSx) for the 2000MY. There was no huge power gain from that.

Dwell time. Strength of the spark. Reduction of power loss due to cable inductance. Much more accurate timing due to significantly reduced latency. An old friend did this conversion on his GN.

[Aurora40]

Much more accurate timing due to significantly reduced latency.
Wouldn't this be about the same? Whether it's a plug wire or a regular electrical system wire, there's going to be about the same length either way. I don't think electricity travels more slowly in plug wires vs harness wires?

Anyway, I agree coil on plug (or coil near plug on the LSx motors) is definitely better. But 25hp better on a ~400hp motor? That just seems unlikely to me.

[65ZR1]

Who made your harness? Might need to figure out a different ignition system someday also.

The company is called the detail zone and makes conversion harnesses for street rods etc. He did have a hard time getting some of the LT5 connectors so the harness took about 8 months to complete. It was a top notch job though.:thumbsup:

[8upZR1]

There is a guy who makes some kinda EFI system called the DUCK or something like that. Howell is his name. I see his add in back of magazines sometimes. Looks cute and says he makes an LT5 harness. Has anyone heard/seen/tried one of these?

For stand alone ignition duties I have now perfected the use of MSD's 6MOD timing computer on LT5's. Its a really nice computer that is laptop programmable for curves, retard, etc. Basically a digital programmable 7. It runs coil on plug from a Mustng Cobra. Worked a lot better than distributor.

I looked into the Digital programable 7 but it runs about 2K where as the 6MOD is only 1K complete with coils and everything. The 7 needs more expensive gear and therefore more expensive. + with the 6MOD you get manual control over base timing.

Lots of the stand alone EFI companies make a Fuel Only computer. I was gonna play with the mega squirt but never got around to it.

[lbszr]

There is a guy who makes some kinda EFI system called the DUCK or something like that. Howell is his name. I see his add in back of magazines sometimes. Looks cute and says he makes an LT5 harness. Has anyone heard/seen/tried one of these?

For stand alone ignition duties I have now perfected the use of MSD's 6MOD timing computer on LT5's. Its a really nice computer that is laptop programmable for curves, retard, etc. Basically a digital programmable 7. It runs coil on plug from a Mustng Cobra. Worked a lot better than distributor.

I looked into the Digital programable 7 but it runs about 2K where as the 6MOD is only 1K complete with coils and everything. The 7 needs more expensive gear and therefore more expensive. + with the 6MOD you get manual control over base timing.

Lots of the stand alone EFI companies make a Fuel Only computer. I was gonna play with the mega squirt but never got around to it.


All some good info to save!

Are you still running the stock ecm with the stand alone ignition? Just curious since I was thinking the ecm needs some inputs from ignition.

[-=Jeff=-]

just thinking about this. I had at one point a F.A.S.T. eDIST

that might work too, I think all the signals are there for the ECM.. I need to look at the document again, but with the eDIST, you would be running the LS1 coil packs.

only thing I am unsure of is if the LT5 crank trigger would work..

pretty sure everything else would though.

[8upZR1]

With the MSD 6MOD I didn't use the factory ECM for fuel, I ran a QFT 750. I wanted to try a stand alone fuel computer like the one from mega squirt but never got around to it.

I looked into the F.A.S.T. XFI system for the LT5. Even with the EDist, it unfortunately will not work with the LT5 trigger wheel. XFI is a really killer system though. Top of the line. You can always mount a trigger wheel on the balancer. Thats what I did for the 6MOD. It's nice cause the sensor mount has a slot that allows for adjustment of the base timing.

[XfireZ51]

just thinking about this. I had at one point a F.A.S.T. eDIST

that might work too, I think all the signals are there for the ECM.. I need to look at the document again, but with the eDIST, you would be running the LS1 coil packs.

only thing I am unsure of is if the LT5 crank trigger would work..

pretty sure everything else would though.

I was talking to Jeremy about this yesterday. He thought that coil packs were like the GN and may be able to use that or LS system.

[Paul Workman]

Wouldn't this be about the same? Whether it's a plug wire or a regular electrical system wire, there's going to be about the same length either way. I don't think electricity travels more slowly in plug wires vs harness wires?

Anyway, I agree coil on plug (or coil near plug on the LSx motors) is definitely better. But 25hp better on a ~400hp motor? That just seems unlikely to me.

Inductive reactance (resistance) to current flow is a function of changing current over time (t) - the shorter the time, the higher the "resistance". Not quite that simple, actually. Induction tends to resist changes in current; either to initial current flow, or current stopping - the key to ignition coil operation.

The two halves of the ignition coil is the primary side and the secondary side. Of course inductive reactance applies to both sides, but there is a difference in the time each circuit half is "operating".

On the primary side, the inductance is not an issue as there is ample time (between spark signals) to overcome initial inductive reactance of the primary wiring and the primary side of the coil and "saturate" the primary winding - "cocking" it and then waiting, if you will.

The spark command comes as a sudden interruption of the charging current on the primary side; "sudden" is the key. The magnetic field in the primary collapses almost instantaneously, cutting thru the much bigger secondary coil in the process. The result is a tremendous (compared to the battery voltage that initiated it) voltage spike that is exacerbated like flood water behind a dam. The "dam" is in the form of the spark plug(s). Voltage builds up to the point it overcomes the combined resistance of the spark gap and the compressed air/fuel mix.

Once the current jumps the gap, it is like the dam broke. However, the current must first flow thru the plug wires and when current flows, the law of inductive reactance cannot be denied. The longer the plug wires, the more induction takes place, and the current flow will be impeded more.

So, due to the very short nature of the plug-side current, induction plays the bigger role on the plug side of the ignition circuit. Reducing the plug side conductors to zero would be the ideal situation.

I don't know how much hp this will make in the case of the LSx vs. the LT5. But, it couldn't hoit!!

Gotta take the dogs to the vet. Mo later!

P.

[-=Jeff=-]

While extra HP would be a benefit of a swap to LSx coils, My main reason for the swap to them would be to eliminate the $$$$$ ignition module and and use more readily avail ignition components

[XfireZ51]

While extra HP would be a benefit of a swap to LSx coils, My main reason for the swap to them would be to eliminate the $$$$$ ignition module and and use more readily avail ignition components

Talk about a WIN WIN!

[Paul Workman]

The LT5 uses a "waste spark" system; two plugs are fired simultaneously from the same coil. So, there is only 4 coil primary charging circuits in our cars. To covert to the LSx with (I suppose) 8 charging circuits would be...interesting. But! I like the idea of having a safe harbor should the spark module crap out someday on my LT5.

I like the way you think, Jeff.

P.

[Pete]

Jeff can you look into it and see what will it take to convert to LSx ignition.

Have you guys seen the price of our ignition module $1000 :jawdrop:
For that price it's either LSx way or MSD.

Maybe i'll sell my ignition module for LSx system.

Pete

[Aurora40]

The LT5 uses a "waste spark" system; two plugs are fired simultaneously from the same coil. So, there is only 4 coil primary charging circuits in our cars. To covert to the LSx with (I suppose) 8 charging circuits would be...interesting. But! I like the idea of having a safe harbor should the spark module crap out someday on my LT5.

I like the way you think, Jeff.

P.
Looking at the output of the crank and the ECM for advance, though, I believe there is info for every cylinder fire event. It just happens that the event will fire two plugs. So if some sort of device could work with the 9 slot crank wheel, feed the ECM the signal it needs, and use the ECM's advance signal to advance the spark, it would probably not matter how many coils it was hooked up to.

It would be awesome to have something to replace the ridiculously priced ignition module! Of course it would require new cam covers, and probably is totally infeasible, but something with no plug wires at all would really clean up the engine bay!

[XfireZ51]

Jeff can you look into it and see what will it take to convert to LSx ignition.

Have you guys seen the price of our ignition module $1000 :jawdrop:
For that price it's either LSx way or MSD.

Maybe i'll sell my ignition module for LSx system.

Pete

Pete,

http://www.eficonnection.com/coilpercylinder/ramjet350_first_start_small.mpg

http://www.thirdgen.org/techboard/dfi-ecm/476926-ls1-pcm-controlled-gen.html

If they can make an SBC run, the LT5 already has the cam and crank inputs. Coil per cylinder has the advantages of tighter spark latency, more accurate timing across the board, shorter coil dwell, hotter spark because now it can be delivered quicker and with a lower inductance loss.
Its a significant reason why the LSx motors put out the power they do.
For our higher revving motors it would help top end. ;)

[-=Jeff=-]

It is the 9 slot that messes it up for the eDIST. but I know the eDIST would work using the ECM timing.. meanign the ECM timing out would feed the eDIST.

Also Paul, remember, the ignition module fires the 2 plugs, with a new set up, you would have a different ignition so the 2 fires per plug is a non-issue.

I will look into it, I am not sure exactly what would work though. I would need to look into it a bit more, maybe this winter :D

[XfireZ51]

=Jeff=,

We may want to check with RBob and Jeremy.

[-=Jeff=-]

=Jeff=,

We may want to check with RBob and Jeremy.

Sure

[8upZR1]

Why don't yall forget the stupid LT5 crank wheel and just bolt a LSx style wheel to the front of the damper like a flying magnet setup? It will solve so many problems......

[8upZR1]

Also, the little plugs in between the head and the valvecover, the one in front of the cams, can be cut to accept a ring seal. If you put a long ARP stud in the cam snout and bolt down the timing chain wheel with a nut & washer, you can have excess length go through the afformentioned seal-in-plug. This extra length can be used to mount a cam wheel in between 2 nuts. The first timeI tried it I had the threads on the stud turned down at the seal but it still leaked. On the second go around I just ran the stud as is and used a slightly larger seal. The threads on the stud acted like a power screw and kept all oil inside the cover, no leaks.

With the cam and crank sensors located outside of the motor it becomes a matter of seconds to bump timing, replace sensors, etc. Another advantage would be that in case you swap to a different EFI system you can just bolt on the appropriate timing wheel.

I know it won't look 100% stock, but then again it wont look that way with LSx coils either.

[-=Jeff=-]

8UPZR1

yes cold use an aftermarket part, but if there is a reasonable solution using the OEM then I am all for it.

I think the current Cam sensor could be reused, I don't think that has to change

[8upZR1]

I guess I can bring myself to understand your point, however, when I think of the LT5 ECM the only thing in my brain is this:
The LT5 came out in 90, ergo the ECM was engineered in probably '84 maybe '85. In 84/85 I was playing Comodor 64, or 8 bit Nintendo. Now its 2008 and I have out grown a comodor 64, and 8 bit Nintendo, and LT5 ECM.

I remember reading somewhere in the registry on a tech page that the early ECM can only resolve RPMs in 250 rpm increments. Like 0-250-500-750-1000. The newer LT5's supposedly read 20 RPM increments. Thats quite an improvement over 250, but is complete shite compared to the resolution of a F.A.S.T. ACCEL, BIG STUFF, MOTEC, etc. The engineers at GM really aren't to blame as they were working with shite to begin with. Even if its original, you cannot possibly argue that LT5 ECM holds a candle to modern EFI controls with modern microprocessors. Why defile your LT5 engine with the original ECM? It barely works, it breaks all the time, parts are impossible to find, it needs all sorts of $$$ ancillary equipment (IGN module), and is totally outdated. Take your LT5 ECM and put it in the box next to your Nintendo. Maybe in 30 years you can whip em out and let the greatgrandchildren learn about how hard we had it in our youth.

If you EBAY your ECM, PROM, IGN module, spare IGN module #1, spare IGN module #2, plug wires, coils, mount, wiring harness, secondary relays, etc. you will have plenty of cash for a F.A.S.T. + money left over to buy drugs. It makes sense to me at least.

[-=Jeff=-]

I guess I can bring myself to understand your point, however, when I think of the LT5 ECM the only thing in my brain is this:
The LT5 came out in 90, ergo the ECM was engineered in probably '84 maybe '85. In 84/85 I was playing Comodor 64, or 8 bit Nintendo. Now its 2008 and I have out grown a comodor 64, and 8 bit Nintendo, and LT5 ECM.

I remember reading somewhere in the registry on a tech page that the early ECM can only resolve RPMs in 250 rpm increments. Like 0-250-500-750-1000. The newer LT5's supposedly read 20 RPM increments. Thats quite an improvement over 250, but is complete shite compared to the resolution of a F.A.S.T. ACCEL, BIG STUFF, MOTEC, etc. The engineers at GM really aren't to blame as they were working with shite to begin with. Even if its original, you cannot possibly argue that LT5 ECM holds a candle to modern EFI controls with modern microprocessors. Why defile your LT5 engine with the original ECM? It barely works, it breaks all the time, parts are impossible to find, it needs all sorts of $$$ ancillary equipment (IGN module), and is totally outdated. Take your LT5 ECM and put it in the box next to your Nintendo. Maybe in 30 years you can whip em out and let the greatgrandchildren learn about how hard we had it in our youth.

If you EBAY your ECM, PROM, IGN module, spare IGN module #1, spare IGN module #2, plug wires, coils, mount, wiring harness, secondary relays, etc. you will have plenty of cash for a F.A.S.T. + money left over to buy drugs. It makes sense to me at least.

While I agree, the one of things keeping me from switching to a F.A.S.T.

Getting it to work with and Satisfy the CCM from complaining when it loses communication with the ECM.

Also which F.A.S.T system would run 16 injectors?

[XfireZ51]

I guess I can bring myself to understand your point, however, when I think of the LT5 ECM the only thing in my brain is this:
The LT5 came out in 90, ergo the ECM was engineered in probably '84 maybe '85. In 84/85 I was playing Comodor 64, or 8 bit Nintendo. Now its 2008 and I have out grown a comodor 64, and 8 bit Nintendo, and LT5 ECM.

I remember reading somewhere in the registry on a tech page that the early ECM can only resolve RPMs in 250 rpm increments. Like 0-250-500-750-1000. The newer LT5's supposedly read 20 RPM increments. Thats quite an improvement over 250, but is complete shite compared to the resolution of a F.A.S.T. ACCEL, BIG STUFF, MOTEC, etc. The engineers at GM really aren't to blame as they were working with shite to begin with. Even if its original, you cannot possibly argue that LT5 ECM holds a candle to modern EFI controls with modern microprocessors. Why defile your LT5 engine with the original ECM? It barely works, it breaks all the time, parts are impossible to find, it needs all sorts of $$$ ancillary equipment (IGN module), and is totally outdated. Take your LT5 ECM and put it in the box next to your Nintendo. Maybe in 30 years you can whip em out and let the greatgrandchildren learn about how hard we had it in our youth.

If you EBAY your ECM, PROM, IGN module, spare IGN module #1, spare IGN module #2, plug wires, coils, mount, wiring harness, secondary relays, etc. you will have plenty of cash for a F.A.S.T. + money left over to buy drugs. It makes sense to me at least.

Actually, the resolution on the LT-5 code is in 100rpm increments. Not sure where you read that its 250. Early C3 ECM like the 7747 had resolution in 400rpm increments. The higher rpm ranges, ie over 2000 rpm, go to 200rpm and then 400 up to 7000rpm. That's for the VE and SA tables. In most cases the aftermarket stuff resolution is considerably less granular than the OEM. That's because the AM stuff doesnt't deal with the same constraints the OEM needs to. In addition, there's much more
logic in the OEM cal dealing closed loop controls. Aftermarket stuff is usually more expensive but more rudimentary in its logic. As old as the
LT-5 stuff is, its still pretty good. Its not as much a question of the processor speed but more importantly the software running the motor.

[Pete]

I don't have tuning issues.
I just want to have a choice to either pay the big $$ for parts that are no longer available or for parts that i can buy from Jeg's or local parts store.

Pete

[8upZR1]

I thought I read the 250 on the registry site, however if you say its 200 or 100 thats probably right. I don't really know 100%, but I do know that 100 rpm still SUCKS. Even an SDS EM4 can resolve down to 2 rpms. When people swap to stand alone they always gain power and consistency. When you dyno a motor with OEM EFI there is always an issue with repeatability. I have seen motors vary by as much as 15HP from pull to pull just from the stock ECM's inconsistency. You will never get a proper engine calibration if your spark and fuel vary +/- 3%. Just wont happen. With a F.A.S.T. or Electromotive box you can rest easy at night knowing that your spark will occur at the correct moment every time. Also the newer boxes, like XFI, have closed loop operation for both WOT and light load. With a wide band & XFI you can just program a target A/F and the box will do the rest. It doesn't get much better than that. Many of the newer EFI systems can even run the 8 additional injectors. I think its the BIG STUFF that can handle up to 3 sets of 8. Also there are tons of companies that make controllers for additional injectors. The best ones I've used are from Japan: Greddy, Apexi, & HKS all make really killer stand alone injector controllers. Greddy even has a simulator module add on that makes setup an tuning easy.

As for the complexity of the code, I can state from experience that microprocessors run a lot better with short, simple, efficient coding. When I was a grad student I took CFD courses with a bunch of Indian and Chinese guys. Late at night I would steal their source code to see how they ran their various schemes. The shorter codes gave the same reslts as the longer ones, just a lot faster. This probably doesn't mean much for the LT5 ECM but when the # of calculations reachs into the millions then speed becomes directly related to the number of lines in the code. The constraints that GM engineers had to work with in the 80's are insignificant today.

I think that NCCCCRS guys should be the only people running the OEM ECM. Think about how far computers have come in the last 20 years. When you buy an LT5 ECM or Ignition module you are shelling out mega $$$ for technology that is just old. I dont see the point. I always want my motors to run as good as is humanly possible, and LT5 controls just dont do it. I love the automotive aftermarket and the products that it produces. More aftermarket support for the ZR1 would be the most wonderful thing in the world. But since that wont happen the only solution is to adapt stuff built for newer cars. For the $$$ I spent on LT5 stuff I could have had a F.A.S.T. + twin turbos + a spare SBC. Instead I have electronics from 1985. It just doesn't make sense to me.

[XfireZ51]

I don't have tuning issues.
I just want to have a choice to either pay the big $$ for parts that are no longer available or for parts that i can buy from Jeg's or local parts store.

Pete

Pete,

The LSx stuff would give you the extra 10-15hp you're looking for.

8up,

"I thought I read the 250 on the registry site, however if you say its 200 or 100 thats probably right. I don't really know 100%, but I do know that 100 rpm still SUCKS. Even an SDS EM4 can resolve down to 2 rpms. When people swap to stand alone they always gain power and consistency. When you dyno a motor with OEM EFI there is always an issue with repeatability. I have seen motors vary by as much as 15HP from pull to pull just from the stock ECM's inconsistency."

I don't even know how you would tune using a resolution of 2 rpm. The VE and SA tables for that would be HUGE! I'd sure like to see it. When I put my car on the dyno recently, hp varied no more than 1-3hp between pulls. Completely acceptable variance when considering heat soak etc.
What was it about the stock ECM that was inconsistent?

[Pete]

Pete,

The LSx stuff would give you the extra 10-15hp you're looking for.



Now your talking my language HP. :wave:

If i can make .500 lift cams work in a LT5 i can figure out some ignition stuff. Operation Winter HorsePower.

So maybe 485rwhp from a stock 350ci :dancing
Pete

[8upZR1]

The inconsistent pulls were all done back to back without cooling time. This probably had something to do with it cause we all thought too much timing was being pulled, even with desensitized Haibek chip. 3% HP variation on a 500 HP motor = 15 HP. You might be able to finagle more consistent dyno pulls but that isnt what you would get if you were running a Mustang Cobra from stop light to stop light. You may be faster on the 1st light, dead even on the second, but by the 3rd you are toast.

I know that isn't very scientific, but I don't believe in test #s generated in closed environment. If your car runs 9's in the 1/4 @ the track with no air filter, ICEE in the intercooler reservoir, cold intake, no interior, bumped timing, etc then it isn't a real 9 second street car. On the street with interior, full tire pressure, your girl friend and her fat a$$ friend, D2O w/o ice in reservoir, normal timing, that 9 sec car is a low 11, high 10 player. If you sub a b*tch*ng wife for that G-friend then itll only go 12's. What do you call a 9 sec car that runs 11's in street trim? SLOW, POS, that gets eaten by a bonafide 10 sec Honda. (yes, they are rare, but they do exist) + Honda guys have small asian girls that dont add a lot of excess weight. Something to think about.

In Miami @ a place called T-Bone's I witnessed a 1999 Porsche GTS put down amazingly consistent dyno pulls. Like 677, 676, 679, 680, 677, 678, all one after another. The dyno operator didn't even slow down between pulls. The motor was cycled up and down, up and down, up and down. The car ran a MOTEC and was being tuned for track day @ Sebring. When you consider the power that 6 was making, that it was Twin Turbo, and in a small room with only 5 6' fans blowing, you can really appreciate what the MOTEC does for engine controls.

There isn't really anything wrong with the factory ECM, it definetely will run the motor just fine, its just old and outdated and crazy $$. For roughly the same $$ you can have a modern system that works faster and more accurately. If originality isn't an issue I would always reccomend the modern aftermarket solution over the old original. Its just a better buy. I dont make my living selling stand alone system BTW.