Hey guys,

I don't really ever post on here, just do a lot of reading pretty much. Anyways, I was in the process of tuning my car but was not able to finish because once the car hits boost, cylinder #2 misfires. I'm thinking bad coils. So i have tried 4 different coil sets and my car will not accept them, they won't even start the car. Then I put my original coil pack back on and it runs just fine (until boost of course). Does anyone have any idea why I can't get the new coil packs to work? Any advice would be helpful. Thanks

Compression good.
NGK LTR7IX plugs
60# injectors

Do not know about the diferent coil packs, but what is your plug gap? If the CEL flashing when this happens?



FU Tuning

.044"

When I was tuning it the engine light was flashing. Since then I haven't gone into boost cuz i know its going to miss

Since your profile is not filled out do not know exactly what your setup is, but by the plugs I say it is a Ecotec. .044 is probably too big of a gap. How much boost are you running?



FU Tuning

I run .035" with around 15 PSI. I believe most people will tell you .044" is a little high - especially without a higher end ignition system.

.035

im at .28 on 14 psi. if i go above 18psi i get spark wash even at .28, but then again my coppers are due for replacement and well, there copper!


running rich? turn the boost up

some of the ignition modules have different length connectors on the coil pack side of the connector. since your vehicle doesnt start when swapping the other coils i bet your ignition module is not seating into the connector on the coil pack all the way.

.044? Damn.

I run .028 at 15lbs. I used to be at .035 then I was having issues at higher rpm. I changes to the ignition coils and lowered the gap on the plugs to .028 and have been good ever since.









~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ

AFRs when the misfire happens? <11:1 and a gap like that is a recipie for misfires...

Sorry about the delay guys. 2003 cavalier. right now i only have my boost controller set at 9 psi until i can actually get into boost to get it tuned. The problem is, as soon as it even sees 1 PSI, starts misfiring. I'm trying another coil pack tonight, if i don't have any luck i'll try gapping down to .035". Are you guys all running the 7 heat range ngks besides turbofire? thanks for all the responses

I will change gap before coil packs.



FU Tuning

Alright I'll try it when i get off work

I tried gapping them down to .030" still misfiring. Got my brothers coil to start my car, still misfiring. Any other ideas? Injector?

Make sure you don't have any breaks in your plug wires. At night, pop the hood and watch for blue arcing from anywhere near the plug wires. Also, bench test your ignition coils by measuring resistance across the primary and secondary windings. If that looks good, check resistance between all if the coil modules plug wires and wherever they go to (need a schematic for that one). Before you check the injectors, make sure you have good fuel pressure (you may not have a test port depending on your motor). It may be a bad pump or regulator. If you still have problems get a solenoid tester to check for a signal at the injectors, if you don't have one try some new injectors.

For what it is worth, it is probably ignition related seeing as it goes away in the higher rpms. If it was fuel related, it usually would get worse.

oldskool wrote:AFRs when the misfire happens?

its not a misfire dealing with rpm at all just as soon as it sees boost. afr is fine till it starts to misfire around 2psi and jumps to about 15. i have good fuel pressure because i have a gauge. If it were bad pressure would it be all the cylinders not just one?

How do i get to the primary and secondary windings? i thought they were sealed in the coil pack

cody allison wrote:its not a misfire dealing with rpm at all just as soon as it sees boost. afr is fine till it starts to misfire around 2psi and jumps to about 15. i have good fuel pressure because i have a gauge. If it were bad pressure would it be all the cylinders not just one?

How do i get to the primary and secondary windings? i thought they were sealed in the coil pack

So as soon as it misfires the AFR goes to 15?

If so sounds like it is just too lean.



FU Tuning

But why is only cylinder 2 misfiring? i thought that was the problem too but no matter how he tried to tune it, it would still misfire.

I run 0.028" and I'm @ 14-15psi

Check your plugs first, even though they were gapped @ 0.044" when you installed them, the heat could have casued them to open up.

I changed my plugs last summer after about 7,500miles of boost, I installed them at 0.032" and when I pulled them after realizing that the car was running like a turd, they were all between 0.047-0.049" I figured out then that I should check them more often.

ROKN20S - aka JuicyJ wrote:I run 0.028" and I'm @ 14-15psi

Check your plugs first, even though they were gapped @ 0.044" when you installed them, the heat could have casued them to open up.

I changed my plugs last summer after about 7,500miles of boost, I installed them at 0.032" and when I pulled them after realizing that the car was running like a turd, they were all between 0.047-0.049" I figured out then that I should check them more often.

More than likely it was just the wearing of the tip causing the gap to increase, but regardless is always good to check them.



FU Tuning

44 is too much, i was at 30 at 14psi and it was fine.. until i put nitrous on



12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]

they were 7IX from NGK too by the way



12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]

have you tried swapping coils and spark plugs to another cylinder? since you know number 2 is missfiring. swap the plug to number 4. if the misffire moves to number 4 then you know its the plug. if it doesnt then swap the coil from number 2 to number 4 and see if the missfire moves to that cylinder. if it does then you have a coil problem. if it doesnt then swap number 2 injector to cylinder 4. if the misfire changes to cyl 4 then you know the fuel injector is bad. if not, then you may need to look at your ignition module.

how do u know number 2 cylinder is the only cylinder missfiring?

Well i had srt4 plugs in it then i went back to the NGKs still a misfire so i really don't think its spark plugs. And i'm not sure how to switch the coils from one cylinder to the other because i thought you couldn't with the ecotec motors?

Misfire was determined by the scanner with HPtuners