Need some help with a P0358 code

[Black3vGT]

Hey guys i'm trying to get my 2006 Gt back on the road again for the first time in 2 1/2 years and I've got everything running but i've recently starting throwing the ignition coil H P0358 code. Searching through past posts on here I learned that the code is for #8, so I pulled the coil, checked the coil connection, checked the plug, checked the injector, checked the the the wiring and everything seems good. After reconnecting the battery everything seems good, sounds healthy feels good it but will eventually throw the code again and start misfiring. After reading posts on here I'm dreading its the PCM, i'm looking for any other suggestions as what can be causing the problem.

 

[datmbn]

Try moving the coil to an other cylinder and see if the problem follow the coil, if it does you have found the problem, otherwise I Think sparkplug or wirening

 

[Pentalab]

When I replaced all my plugs a few years back, all the misfires vanished. It didn't throw any codes, but the areoforce gauges will depict misfires on one of their 32 parameters I can look at. I would typ see 3-7 misfires on a 20-35 min drive across town, nothing I could feel or hear. Swapping the coil to another position is good advice and will verify /eliminate the coil as the issue. If it's still there on #8, it's a wiring issue.

 

[86GT351]

Hey guys i'm trying to get my 2006 Gt back on the road again for the first time in 2 1/2 years and I've got everything running but i've recently starting throwing the ignition coil H P0358 code. Searching through past posts on here I learned that the code is for #8, so I pulled the coil, checked the coil connection, checked the plug, checked the injector, checked the the the wiring and everything seems good. After reconnecting the battery everything seems good, sounds healthy feels good it but will eventually throw the code again and start misfiring. After reading posts on here I'm dreading its the PCM, i'm looking for any other suggestions as what can be causing the problem.

First thing would be to move the #8 coil to another cylinder and see if it moves to that cylinder. Easy diagnosis. With it sitting for 2 1/2 years I would consider a new set of plugs. Also look into replacing your Fuel Filter. Could be some bad gas as well.

 

[Pentalab]

Bad gas smells rancid...and adding 'sta-bil' etc to bad gas won't turn it into good gas. Bad gas can easily screw up injectorS. Make sure any new /existing plugs are gapped correctly.

 

[redfirepearlgt]

Pretty certain that the code is specific to the COP and related circuit. THe FI failing to work would generate a different code due to lack of fuel if memory serves me correctly. Pretty certain the S197 PCM has the ability to discriminate a misfire with respect to the COP vs a fuel starved misfire from a malfunctioning FI. As mentioned twice before first swap COP's between two cylinders and observe to see if the P code changes or stays the same. Then to further diagnose, pull both COP's and sway ONLY THE BOOTS and reinstall. Run again and see if the problem once again changes back or stays the same. It may only be a boot that is failing and allowing the spark to short across to the head rather than making it to the spark plug. BE sure to inspect all of the wiring from that cylinder back to the PCM and look for nicks, frays, cut wire, or poor connection at the PCM connector as well as the COP connector. A car sitting for a long time could have gotten rodents in it which like to chew on wiring insulation(for a stretch of time insulation was being made from soy plastics). Last but certainly not least, if the problem is staying with Cylinder 8, even after trying another spark as also mentioned earlier, you may very well be correct that the PCM is failing. The PCM completes the path on the circuit for the COP to fire when commanded. If that power transistor, SCR, or FET (which ever it may be has failed open, the COP will never function.

 

[Black3vGT]

Thanks a bunch for the replies guys, I'll check all the suggestions. Real quick I did switch the coils, after starting and letting it idles 2 or 3 times the same code did come back, but also as soon as I switched the coils reconnected everything the car is saying I have 0 miles to empty but the gauge is showing 3/4 tank. First time it's done that.

 

[redfirepearlgt]

No need for concern on that IMHO. It should return once the car is driven or has set running for a period of time. Chances are on a hunch that the Keep Alive Memory that holds only trending data and not the tune was reset (that can be done through a tuner device or by simply disconnecting the battery cable for an extended period of time). Once the car is driven and the PCM can generate data to determine that again, it should return. May take some time, but it will look at fuel level vs consumption and so forth and begin generating the result of that algorithm which will update the display.

Did you swap boots only? Boots on the COP's often develop pin holes which allow the spark to jump to the engine block. If the COP or Boot or both are bad on the original device in cylinder 8 (driver side last cylinder in the back) and it is swapped with cylinder 7 (driver's side third to last cylinder in the back) the code should have changed to P0357. clear the codes and restart the car several times after each swap just to be sure the PCM is generating the code correctly at each startup. I'd hate for you to send the PCM out for rebuild only to find it was okay. And please, please, please don't forget to recheck and recheck your wiring on that system again.

Best of luck to you.

 

[46addict]

When I replaced all my plugs a few years back, all the misfires vanished. It didn't throw any codes, but the areoforce gauges will depict misfires on one of their 32 parameters I can look at. I would typ see 3-7 misfires on a 20-35 min drive across town, nothing I could feel or hear. Swapping the coil to another position is good advice and will verify /eliminate the coil as the issue. If it's still there on #8, it's a wiring issue.

Do you recall the PID that counts the misfires?

 

[Black3vGT]

So today I swapped the 7-8 spark plugs and ran the car until the code came up again and this time it was 0357! So it looks like we found the problem. Thanks guys.

 

[86GT351]

Replace the coil and also the plugs

 

[redfirepearlgt]

So today I swapped the 7-8 spark plugs and ran the car until the code came up again and this time it was 0357! So it looks like we found the problem. Thanks guys.

BINGO!!!! Problem followed the COP. You can take it further or just replace the boot and COP both and be done with it.

GOOD JOB!

 

[Pentalab]

Do you recall the PID that counts the misfires?

I just cycled the aeroforce gauge's 32 items till I get to the one labelled... 'misfires'. It numerically counts the misfires.... between starting the eng....and shutting it off.

 

[Lime1Gt]

So today I swapped the 7-8 spark plugs and ran the car until the code came up again and this time it was 0357! So it looks like we found the problem. Thanks guys.

So did you find the plug had a crack in the porcelain or would it just not fire?