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Hello Friends,
I've been lurking around for a few months, since March when I purchased my first Corvette. Its a 2001 Z06 in Torch red with 65K. It had a couple of small things that I've been able to research and fix but I'm a bit lost on this one. Electrical is a mystery to me and is causing me some confusion.
The issue started as a misfire. In the morning to work no issues. Left for lunch and it just started running really rough and had a lot of gas smell
Car threw P0300 (random misfire)
I changed to plugs and wires with OEM parts (getting the wire on the plugs is a true pain in the **** - previous owner had MSD wires and tossed the metal heat shields. I have those on order.)
Plugs and wires didn't fix the issue, but I did get P0352, P0354, P0356, and P0358 AND I'm also getting a low oil notification. - The oil level is fine.
I swapped the coil packs and the issue stayed on the even side
When it's started. The odd header gets to temp. The even bank stays cool to touch.
I used a smart test light and checked all my fuses in the engine bay. They were all good.
I also used it to test the pins on the harness going into the coil pack harness. The Black/White ground wire was dead.
I thought that the dead wire was grounded on the post next to the battery. After some looking again today - I believe I was wrong and it is grounded on the back on the engine. G107 is the ground point.
Assuming the ground is on the back of the engine - Can I get to the ground without pulling the intake?
Sounds like one bank is not firing. The ground for the coils is at the back of the drivers side head. If you get a light and look back there you should see the ground lug and wires. There are two wires on the ground lug. You can take the ground off without removing the intake.
Welcome and the ground for each bank of coil packs go to G107 which is at the back of the left cylinder head (pictured)...not easy to get to or even see for that matter...how did you determine that the ground was bad ??... if you used an ohm meter that is NOT the best way to test...get yourself an old headlight with both wires attached (pictured) and run the positive wire to battery positive and the negative to the ground you are testing...the light should be bright if the ground is good...you can make yourself a jumper wire by back probing the black/white wire at the connector between coil packs 4 and 6 and attach the other jumper wire to a good ground...see if the misfires go away...you may have a broken wire somewhere between the connector and G107 !!
Thanks for the help! I checked the ground on the back on the engine. Mine looks just like yours and I was able to get my test light on it and had a good ground (at least to the metal terminal). I can't really get a much better look than you did with your picture and I'm not sure I would be able to get it off with the air intake on to look at the condition of both wires.
To determine the ground on the even side was the issue I used a test light. It shows different lights for power and ground wires. On the odd bank, it identified the ground wire and on the even side I get nothing. I also used a multi meter -- and assuming I used it correctly, also showed no ground.
If I'm honest, my multimeter skill/knowledge leaves a lot to be desired.- I've watched so many electrical diagnostic videos on you tube that I hope and *think* i got it right looking for continuity but could be wrong.
Right now, I'm thinking I should just pull the intake to check the harness between the coil pack plug and the ground. Any other ideas before I go that route? I really don't want to pull it off again...
Are you using a Power Probe ??...to test grounds you really have to “load” the circuit !!...like I had mentioned using these headlight bulbs is the way to go and not using an ohm meter !!...you may have to start unwrapping the electrical tape and see where you problem lies !!...this pic is loading the coil ground !!
Even bank misfire
