misfire under boost, have log
 

FD with haltech PS1k, fresh stock port 13B-REW with S4 N/A rotors. Im having trouble with what seems like ignition breakup or something. whenever i get above 8psi or so it seems to hit a wall and engine makes a bpbpbpbpb sound lol. AFRs around 10.7-11.0, timing pretty conservative. I am running LS2 truck coils which i suspect is causing the problem. I tried messing with coil charge time, and problem gets worse with lower values, ive tried 3.0 up to 5.0. Ive read they are saturated by 6ms or sometihng and may start auto-triggering so i was worried about trying over 5.0 ms. Are the LS2 truck coils shit or what else could cause this?

here is a log of the problem, several boost runs, i let off each time it started misfiring. the charge time is 5.0 ms in these logs. you will need Haltech PS1k Data log viewer

http://s000.tinyupload.com/download....11902137262582

i had the same problem before the rebuild on the stock rotors, but would happen at higher rpms. I have not been able to boost this car properly since installed the PS1k and LS2 truck coils

i couldn't make heads or tails of your log... but there seems to be holes in the datalog... suggests you probably have a wiring issue ... most likely a short in the wiring, i would spend some intimate time with your harness, checking and rechecking all the connections.

oh the data log was auto-generated, whenever boost is above 0psi is starts appending to the file

For some reason, I can't download the file. Can you email it to me? ludwigmotorsports@insightbb.com

Replied to your email.

i swapped in a set of FC coils and problem has gone away. out of curiosity, i set up a test with o'scope and FC coils actually put out more energy than the LS2 coil. LS2 has higher voltage, but the FC discharge duration is about 3x as long. Im going to order a pair of IGN-1A and test those too

moral of story.. LS2 coils suck

How about LS1s? I'm running those in my FC3s (haltech branded) with a sprint RE. Maybe you had some bad coils.

Interesting about the FC coils. Currently running four leading ignitors with four trailing coils and have had no issues.
Any update on using the new IGN-1A coils?

LS2 coils work super on all the cares that I know of, they have to be wired correct, if not you experience problems like that .

maybe i have knockoff ls2's?

the IGN's work ok, i am running a set for leading ignition and had no problems, but i havent really turned up the boost yet. but here is what they look like on an o'scope:

https://i45.tinypic.com/zwewbb.jpg

what you care about is peak voltage (height) and discharge duration (length). the IGN's have high voltage, but not as much duration, so overall energy (area under the curve) is about the same as FC coils. i am not sure which is better for combustion, peak voltage or discharge duration.

I am looking at running a custom ignitor on a set of FC coils.. if you look at the bottom left capture, that is an FC coil with factory ignitor bypassed, instead driven by a simple high-current transistor circuit charged for 6ms.. its a freakin beast! the factory ignitor tops out around 3.5ms

there are multiple LS2 coil models and they are different from each other, you need to specify which one you're using/referencing

this is typically where most people go wrong ... The D585 "truck/Yukon" coil is the decent one, the others not so much

can't really go wrong with the IGN-1A and it will take more dwell than you used on the scope image, but you need good/appropriate power & ground wiring to handle the higher than typical amp draw loads

I'm sure the FC coil was never intended for that amount of loading so the lifespan under the modified circuit circumstance may be questionable

gxl90
what plugs are you running and what are they gaped to?
thanks

I agree with T-7, your conclusion that 'LS2 coils suck' seems suspect. You may have lost interest since you've developed a good workaround, but what plug wires were you using?

these tests were on the D585 truck coil, the one with the heatsink. i picked up another one from local store to verify, and got the same results..

i am running factory trailing NGK 9's spark plugs all around.

the captures were made with no spark plug.. just firing them into a 800V string of zener diodes and a 10 ohm resistor, and measuring the voltage across the resistor with the o'scope. basically this is a lot more load than the coil would normally see when connected to a spark plug. if connected to a spark plug, the discharge duration will be a lot longer due to less load on the coil

I have been running the IGN's for a while and haven't had any problems. last weekend i finally got around to installing the FC coils and ended up using a subaru ignitor, which puts out a little more current than the factory ignitor, and is a bit more rugged than my custom rig-up lol. i immediately noticed smoother cold start and idle and still boosting with no problems.

my conclusion is that rotaries like long duration spark, not hotter output

That depends on the conditions inside the chamber. Chamber pressure, fuel type, fuel quality, fuel quantity, exhaust dilution of charge, etc., etc. will drastically alter the amperage required to bridge the plug gap. The only way to truly get an idea of what the coil is going to do is to test it with a pressure chamber and a control gas atmosphere. Given that your load is a control load, it's fair to say that your tests are able to give a fair comparison of one coil v. the other. Just not indicative of what the load on the coil is actually going to be in a running engine.

Interesting info on the D585 coils. You know I too started having weird running problems when I switched from Ls1 coils to the D585's. I have also done some other mods at the time when I did the switch but wasn't able to isolate the problem to the coils. I'm gonna do some back to back testing and re-install the Ls1 coils and them switch over to the D585's and see what happens.

here is a shot of the d585

https://i45.tinypic.com/dmxysx.jpg

I wrote this on the other board in gxl90rx7's similar thread there. You guys need to be careful with the D585 truck coils.

"Careful with the truck coils (silver heatsink) and long dwell times. Last year we had some issues with detonation running these coils on a car that had been running the real LS2 (non-heatsink) coils with no issues at all. We installed the truck coils and had the charge time set at 6.0ms. That's when we got the detonation. Pulled those coils, installed IGN-1As and no problems. Later saw a bunch of GM guys in the know on yellowbullet.com saying they won't even run the truck coils anymore. Turns out they will auto-discharge when dwelled hard as an over current protection. The word is that not all of them do it and there seems to be no rhyme or reason to when they do it. If you run them, it's recommended to not charge them over 4.5ms."

^ Hell yea! Thx for that info as I've been running 5.0 ms. I'm still gonna do some back to back testing for my own experimenting reasons.

today i got my hands on an MSD 6A box.. CDI multi-spark output. i tested it on the bench with factory coils and it basically ups the voltage x4, but duration is only 100 us (vs 1300 us factory duration) per spark. But it re-fires 8x per charge. above 3000 rpm, it only sparks once. so above 3000 rpm, it puts out 4x the current from factory, but 1/10 the duration. im thinking about installing this and see if it breaks up at high rpm.. that would prove that short duration was causing my misfires

Haven't had good luck with the ign-1a coils on two setups were working on with similar ignition cutout issues. Played with filters & dwell air fuels and timing are very good. I'm going to be forced to try another brand of coil if I can't figure it out....

mzrx7
can you explain more what happening during your two step problem? and what plugs you running and gap.
thanks

Its not a 2step problem it does it under load around 5500-6000 area. All trailing 9s they aren't gappable

Trigger problem.

Ive done everything i could possibly think of... seems like this is becoming a big issue with several members.