Coils Went Bad????
Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
Coils Went Bad???? Guys, I have a problem. My '01 Z28 with TSP MS4 cam, and PRC stageI LS6 heads is giving me problems. I can't figure out what the problem is. When I turn the car on, and it worms up, it starts to backfire and the engine vibrates a lot. When I try giving it some gas it just stumbles/hesitates and will only go very slow. The check engine light came on and it's saying something about all the coil packs being bad or something. At first I thought it was the wire touching the headers EGR pipe, so I wrapped both the egr pipe and the wire, and the problem still continues. What can be the problem? Can the coil packs really be all bad?
what i've learn about cars is that anything can go bad at anytime. so the coil packs could definatly be the problem. also check for fouled plugs first. if there black clean them off and give it another shot 
usually if your car is missing the SES light will flash iirc, but are you saying that its doing it all the time, or only after it warms up? Is this first time your starting the car from swapping cams, or has it ran fine and this just started?
Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
The car was running fine for a couple of months after the install. The problem starts when the engine warms up. It starts to backfire and shake a lot. I'm going to pull the codes tomorrow, but I know it said something about the coils. It was suggested that it could be the ground for the coils behind the cylinder head, so I might as well check that out since it's given me problems before. I did the cam swap about seven months ago and it was running perfectly fine. The problem just started last week.
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could be the coil harness, plug wires, grounds, did you have a tune after the cam? crank relearn?
the chances of 4 or 8 or hell even 2 coils going bad at the exact same time is about as likely as you hitting the powerball twice in a month
the chances of 4 or 8 or hell even 2 coils going bad at the exact same time is about as likely as you hitting the powerball twice in a month
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Verdad Gallardo Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
Yup, I had the car tuned and everything. I'm going to pull the plugs and check them, and I'm also going to check all grounds. I was going to post the codes today, but was at work all day. I'll do it tomorrow.
As for your problem, it sounds like something is wrong once it goes into closed loop (warms up). If it were a ground for the coils then you would notice it when cold as well. I would try to get a reading on the o2 sensors. I bet you have an issue there.
Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
Yeah, that's the beauty of not having a distributor or opti-crap. It's virtually impossible to lose multiple coils at the same time or even more than one for that matter unless you just keep driving it with a bad one until the others crap out.
As for your problem, it sounds like something is wrong once it goes into closed loop (warms up). If it were a ground for the coils then you would notice it when cold as well. I would try to get a reading on the o2 sensors. I bet you have an issue there.
As for your problem, it sounds like something is wrong once it goes into closed loop (warms up). If it were a ground for the coils then you would notice it when cold as well. I would try to get a reading on the o2 sensors. I bet you have an issue there.
Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
I finally was able to go out and pull the codes. They're all ignition coil related codes:
-P0351 Ignition Coil A Circuit P0352
-P0352 Ignition Coil B Circuit P0353
-P0353 " " Coil C Circuit P0354
-P0354 " " Coil D Circuit P0355
-P0355 " " Coil E Circuit P0356
-P0356 " " Coil F Circuit P0357
-P0357 " " Coil G Circuit P0358
-P0358 " " Coil H Circuit P0351
I tried turning the car on a couple of minutes ago and it comes on for a second or two, but cuts off immediately.
-P0351 Ignition Coil A Circuit P0352
-P0352 Ignition Coil B Circuit P0353
-P0353 " " Coil C Circuit P0354
-P0354 " " Coil D Circuit P0355
-P0355 " " Coil E Circuit P0356
-P0356 " " Coil F Circuit P0357
-P0357 " " Coil G Circuit P0358
-P0358 " " Coil H Circuit P0351
I tried turning the car on a couple of minutes ago and it comes on for a second or two, but cuts off immediately.
A review of diagnostic literature on those error codes points to: (a) a short to ground, in this case one that affects all eight coil circuits; (b) ECM connectivity; or (c) a problem with the ECM itself.
Id go with a ground issue. Aside from the PCM, thats the only thing linking all 8 coils together. You also swapped heads recently. Its possible you forgot to torque the coil ground back down since its such a PITA to reach or it came loose/broke
If you have a multimeter unplug a coil connector (the big white one on a valve cover) and do a continuity test from the black wire to the engine block then to the neg battery post. If you get more than a few ohms of resistance between either, then its a ground issue. It wouldnt be a bad idea to repeat the test from the 4 PCM connector grounds as well
If you have a multimeter unplug a coil connector (the big white one on a valve cover) and do a continuity test from the black wire to the engine block then to the neg battery post. If you get more than a few ohms of resistance between either, then its a ground issue. It wouldnt be a bad idea to repeat the test from the 4 PCM connector grounds as well
Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
Id go with a ground issue. Aside from the PCM, thats the only thing linking all 8 coils together. You also swapped heads recently. Its possible you forgot to torque the coil ground back down since its such a PITA to reach or it came loose/broke
If you have a multimeter unplug a coil connector (the big white one on a valve cover) and do a continuity test from the black wire to the engine block then to the neg battery post. If you get more than a few ohms of resistance between either, then its a ground issue. It wouldnt be a bad idea to repeat the test from the 4 PCM connector grounds as well
If you have a multimeter unplug a coil connector (the big white one on a valve cover) and do a continuity test from the black wire to the engine block then to the neg battery post. If you get more than a few ohms of resistance between either, then its a ground issue. It wouldnt be a bad idea to repeat the test from the 4 PCM connector grounds as well
Thread Starter
Joined: Oct 2007
Posts: 446
Likes: 1
From: Oakland, California
I forgot to as, when testing, does the car have to be on or just the ignition on the on position? I tested it with the ignition on the on position and got 4ohms. I also checked the ground behind the driver side cylinder heads and it appears to be connected. Where are the rest of the coil grounds located?
