Been getting a p302 and p300 code at idle over the past couple weeks. Scanguage shows that 99% of all the misfires occur on cylinder 2. Any ideas where I should start? Plugs, coil pack,...? I have a couple month old AC delco stock plugs in there now. The misfiring started after I had to replace my tensioner due to it practically exploding! I noticed as well that my volts drop down to 13 when the fan kicks on and go right back up
to 14.5.

Swap plugs out first if your running older plugs. I had issues until I closed plug gaps doen to .030 and I swapped to ngk plugs that are one range cooler. Also make sure your spark springs are fully seated on the coil pack n plugs and throw some dielectric grease in there for good measure.

i have the same problem only cyl 1.... ive changed plugs 4 times from srt plugs to ngk iridium 2 steps colder even stock at idle and still i get a miss also tried the coil pack changed that... then went to the 2200 coils and stock delco plug wires from a 2200 still have that misfire at idle... ive had it with the lsj incectors and my current 60# injectors... so its def something id like to fix as well...

What is your plug gap at?

My gap is stock. I assume you were talking to ecotecnic? I have some 1 step colder NGK (6509) LTR6IX-11 Iridium IX Spark Plug (the ones everyone recommends on here). I guess I'll try swapping them out. So you recommend .3 gap on those?

I ment to say I have the NKGs sitting new in box haha. The AC Delcos are what is in the car now.

Yeah I'd close the gap a bit, if your running the stock pulley on the blower, I'd close the gap just a cunt hair then run the car and if the issue comes back close it a cunt hair more and try again.
I was talking to ecotecnic as well.

Forgot to add that my plug gap was with a 3.0 pulley but being at different parts of the country with elevation and humidity, blah blah blah will make each car slightly different thats why I suggested trying to close the gap a little bit and working from there.





Edited 1 time(s). Last edited Tuesday, February 14, 2012 6:54 AM

If you guys could list what plug you are running and what boost level and compression ratio, I can dial a plug and gap in for you.

Its a common issue. Mine was fixed from a combination of new plugs and realizing that one of my plug boots was a little bent. It still throws the code from time to time and for the life of me I cant figure why. It has to be a tune thing that either I cant fix or we just dont have access to.


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Jason I'm running the GM flash with stock pulley and lsj injectors. I see about 10psi at wot. Not sure on the compression. How would I figure that out? I have the nkg 6509.

"NGK (6509) LTR6IX-11 Iridium IX Spark Plug (the ones everyone recommends on here). "
Thats just for the stage 1 setup right?
I was under the impression the NGK (6510) LTR7IX-11 is better for stage 2+ m62 setups...
I am about to go buy these ($8.90/each!) at NAPA so Ive got them ready when i do the install in a few weeks.


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

First the plug gap should not affect this misfire at idle. He stated at idle.

I have found the Eco's like to misfire at idle unless running rich.

I recommend the NGK #3787, they cost a little more, but are pre gapped at .032



FU Tuning

arent all the iridium ones pregapped? what makes the 3787 different from the 6510?
btw locally NAPA and Advanced Auto had em, $8.89 - NAPA, $9.99 - AA


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

blu04DD wrote:arent all the iridium ones pregapped? what makes the 3787 different from the 6510?
btw locally NAPA and Advanced Auto had em, $8.89 - NAPA, $9.99 - AA

3787 I believe is 1 step colder, but are pre gapped at .032.

The 6509's and 6510's are pre gapped higher. Around .044 I believe.

NGK recommends not to change the gap more than .006 from the facotry gap. So going to a .032 from a .044 would be going against the NGK recommendations.

I have had a few M62 Eco's run these plugs with no issues, and no gap changes. They cost more, but I think they are worth it.



FU Tuning

but i thought the 6510's were recommended for higher boost / stage 2 and up cars because they run 2 colder...? at least they are what ive seen a lot of ppl saying they use.
i just want to use something good, dont really care what it is and need to get them soon!


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Of course everyone has different opinions.

We ran 6509's on a car that made 314whp, and 17psi.

GM kept stock plugs for the M62, so truly 1 step colder is more than fine.

I wouldn't go to 2 steps colder until 20+ psi.



FU Tuning

Changed the plugs same thing is happening. The ac delcos looked pretty good too. A little black, but nothing too bad. I checked for vacuum leaks and I am not finding anything. I also noticed it will misfire on the highway going 70 when I let of the gas a bit going down a hill. When that happens its sort of random on which cylinder it misfires on. It does not misfire under load or boost at all only in high vacuum.

Sure its misfires when you coast down on the highway and not just fuel lighting off in the exhaust from decel cut?


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Yeah I'm using a scan gauge. I went to check the oil today and found a bunch of white gunk on my dipstick!

Was the engine cold? In the winter white gunk is normally condensation. I would get the car up to temp and drive it up to temp for a half hour, if your oil looks like a milk shake after that, then your misfire is form low compression due to a blown HG.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

I had just drove it for 10 min. The oil looks fine there was just some white goo on it when I took it out a couple times. After that it was fine. Ill check it tomorrow and see if its still white. I hope its not the gasket! How much does that usually cost on these cars?

in colder months the white goo will be there you should see what the valve cover will look like thats why short trips are hard on cars cause they don't get hot enough

if you update your profile we will know if that pertains to you but righ tnow we have no clue where u are

do you have a lazy injector??????
move your injectors around
1-2
2-3
3-4
4-1

see if the misfire moves if not swap out your coil pack from a car you know is good i did that and found i had a bad coil pack



JBO since July 30, 2001

Yeah it was really cold here in St. Louis, MO. Its been like 45-50 the last couple days. We have crazy ass weather! I'm going to try swapping the injectors around tomorrow. We'll see if it moves. I'm really leaning towards vacuum leak. I did reuse the old o-rings on the injectors. I wonder if that could be causing a vacuum leak? If that doesn't work O' Reilly's has a BM coilpack for like $100. I can try it and if it still misfires just return it.

Sorry its a BWD coilpack.

Put new o-rings on the injectors. Seems to have fixed my issues. The milky white stuff did not reappear on my dipstick.either. it has been 50 here the last couple days so I guess that was
just from the cold.