Thread: Your not so typical misfires?

Ok so awhile back i noticed i started getting these random misfires showing on my torque app so i started with replacing parts in hopes to solve this issue.

Parts replaced include:
al 104s (gapped .055)
delphi wires
icm from a low mileage impalla at jy
maf
ac delco fuel filter
vac lines
sea foam
02 sensors

Still seeing these misfires
I checked for any exhaust leaks or vac leaks and nothing.
I also testing my fuel pressure and pressure was a little low befor replacing the fuel filter but after that was fine but i am unable to test while driving because my hose with my gauge wasnt long enough but im seeing the misfires at idle anyway so it shouldnt matter.

I took the car to get tuned my Snowflake and when i did he noticed i was running pig rich and my injectors were going static so he tuned the car and it was running better than ever. He also showed no signs of misfire on his dhp so i thought it was just my torque app sucking. This tune was done without a wideband at the time and befor i threw on the 3.6.

Well shortly after I had a check engine light. One code was due to not having an egr and he forgot to get rid of it when he tuned it but then another i had a misfire on cyl 4.

Ive been really busy and having really had a chance to look into the car. Until today i finally got my aeroforce working cus of a bad cable. Well i looked at my dtcs and noticed i now have a p0300 instead of a p0304. So i scanned for misfires and am getting random misfires across all cylinders.

So i went for a run scanning for knock watching my wideband and also my timing.

At wot im seeing around 12.5-13 on the wideband. around 11-14 on the timing and i start to knock (1-3.5) when the wideband goes under 13

So im lost on this. Yea the car need to be retuned with the 3.6 and wideband but im thinking there is another underlying issue. Maby my fuel pump is bad and hense the reason my injectors were going static? But then again i wouldnt see misfires at idle when my fuel pressure is reading fine.

What's your fuel pressure at?

lim gaskets ever been changed?

Originally Posted by REDCOMPG

What's your fuel pressure at?

I know it was where its supposed to be on an 04 car. Somewhere around 60-64 i think. Ill go outside and check right now for the hell of it.

Originally Posted by Below Average Joe

lim gaskets ever been changed?

ofc


Edit:yup reading 59 psi right now

ofc?

Originally Posted by Below Average Joe

ofc?

Ofcourse

i'm interwebz illiterate.....

So i was thinking about all probable causes for a misfire and something dawned on me. When i got the car i did replace the lim gaskets but when i did i was without a vehicle and had no way of getting anywhere. Well after i tore everything apart i forgot the lock tight. So i just cleaned up the bolts and torqed them down. Is it possible that maby the bolts came lose and i have an intake leak causing all my issues? I guess i could go recheck the torque but at the same time wouldnt this show up scanning my vacuum cus im reading good at anywhere from 20-22.

Originally Posted by lewis1952

misfires ergo firing. After all you have done ck cam and crank sensors and coils.

When i swapped the icm i grabbed the 3 coils aswell and no difference with them not to mention i dont think all 3 coils would be bad.

Ima do a case relearn with my aeroforce for ****s and giggles. I just dont feel like replacing the cam and crank sensor for no reason.


Edit: Have i mentioned how much my car sucks ass? Just scanned my codes again and p0136 (bank 1 sensor 2) But i replaced it less than a year ago with a denso. Maby cus my car was running so rich it ****ed them up?

Or maby its because i had to extend that harness when i installed my headers and where i soldered in the extention its corroded. I used shrink wrap and then wrapped it with electrical tape though. This car is driving me nuts.

59 psi lmao damn

Originally Posted by REDCOMPG

59 psi lmao damn

i dont get it?

My pump is dying so I get nowhere near 59 psi.

Originally Posted by REDCOMPG

My pump is dying so I get nowhere near 59 psi.

Oh ic, Hey btw you said on another forum that you had no problems doing a case relearn with your aeroforce? Im having the same thing the other guy was. I start it and it tells me to press in ebrake and release so i do then it says to rev to 4-5k. My car rev limits while in park at like 3.8. then it tells me to shut off and restart in 30 seconds. But when it says to rev it says wait till the pump turns off? but it doesnt it just goes to the next screen.

Weird mine did it just fine the first time around but after that I just do it this way...dare i say do it the old fashion way


No case learn is needed if you don't get a check engine light.

For 2004 Grand Prix only:

Set the parking brake to disable the daytime running lights system to avoid draining the vehicles battery.
Try to start the vehicle by turning key to the START position (using a Master Pass-Key key, not a Valet key).
Observe the SECURITY telltale on the driver information center. Allow the key to fall back into the ON position. DO NOT TURN THE KEY TO THE OFF POSITION.
After no less than fifteen minutes turn OFF the ignition and wait for ten seconds.
Try to start the vehicle by turning key to the START position (using a Master Pass-Key key, not a Valet key).
Observe the SECURITY telltale on the driver information center. Allow the key to fall back into the ON position. DO NOT TURN THE KEY TO THE OFF POSITION.
After no less than fifteen minutes turn OFF the ignition and wait for ten seconds.
Try to start the vehicle by turning key to the START position (using a Master Pass-Key key, not a Valet key).
Observe the SECURITY telltale on the driver information center. Allow the key to fall back into the ON position. DO NOT TURN THE KEY TO THE OFF POSITION.
After no less than fifteen minutes turn OFF the ignition and wait for ten seconds.
Start the vehicle.

DH you've been going out of your way a lot to smear me lately.

I opened up OP's bin file to see what I changed.
AFR is leaned out 6 tenths, nothing else was changed with the fueling.
I remember telling him that I don't make it a habit of playing with fueling without a wideband.
I do know that the stock tunes come pretty rich, so 6 tenths wasn't something I was too concerned about.

I told OP we should retune it ASAP with his smaller pulley (especially it being GenV) on the wideband.
That was back in September.

I'd be more than happy to give you a retune and check the car out to see if we can find the source of the misfires, for free, even though it's been 7 months since I've touched the car.
Hopefully you've got no damage.

edit: just looked at the logs.
We were commanding AFR in the mid 11s, fuel trims were tight, and we pulled to over 100mph back to back with no knock.

I've had dozens of stock tuned cars on the dyno AFR is always in the 10s.
Show me a stock tuned near stock car with AFR in the 12s at WOT.
You're out of your mind as usual.

according to the logs, when the OP left his IPW's were 21-22ms according to DHP
Whether that's accurate or not is kind of irrelevant since fueling was barely touched and the car ran great with no knock.

Just for clarification, his pulley swap was done after I tuned the car.