Ignition troubleshooting - Coil or Plug bad?
Ignition troubleshooting - Coil or Plug bad? Ok, I've recently installed Pacesetter coated RACE style headers and ORY. I ran open headers WITHOUT o2's installed for about a week while I waited on my o2 extensions to get here (rear o2's are deleted).
It ran fine for awhile open headers but then it started dieing and had a fluctuating idle... If you didn't give it a little gas it would die. I then had the ORY welded up, the o2 extensions installed, and the rear o2 holes plugged. Problem continues....
The car vibrated real bad and feels like its missing. Replaced the wires with MSD SuperConductor 8.5mm wires. Problem continues.
Place a timing light on the wires and one cylinder on each bank (#4 and #5) and get no signal... timing light gets a signal from the other wires (couldn't check #6 and #8 because of the heat because the car had just been running)
My question is this? Is the coil bad or is it the plug?
- The coil should still be sending a signal through the wire even if the plug is fouled correct?
- Pulled the plug on #5 and it was black all over (running rich because of open headers without o2's installed). Cleaned it a little bit and stuck it back in and reinstalled the wire. Timing light still has nothing. Uplug the coil and nothing changes. So I am basically running on 6 cylinders or less.
It ran fine for awhile open headers but then it started dieing and had a fluctuating idle... If you didn't give it a little gas it would die. I then had the ORY welded up, the o2 extensions installed, and the rear o2 holes plugged. Problem continues....
The car vibrated real bad and feels like its missing. Replaced the wires with MSD SuperConductor 8.5mm wires. Problem continues.
Place a timing light on the wires and one cylinder on each bank (#4 and #5) and get no signal... timing light gets a signal from the other wires (couldn't check #6 and #8 because of the heat because the car had just been running)
My question is this? Is the coil bad or is it the plug?
- The coil should still be sending a signal through the wire even if the plug is fouled correct?
- Pulled the plug on #5 and it was black all over (running rich because of open headers without o2's installed). Cleaned it a little bit and stuck it back in and reinstalled the wire. Timing light still has nothing. Uplug the coil and nothing changes. So I am basically running on 6 cylinders or less.
Not sure about the timing light test results, but I'm betting it's fouled O2's...
You could always swap plug/wire/coils around to see if the timing light results change...
However, if it ran fine for a week and progressively got worse even after you swapped wires, that sounds like fouled O2's - that suspicion is made even more likely with the open headers/rich tune.
Have you scanned the car for misfires and O2 voltages ? Pulled the plugs to look at them ?
Rob (Bad30th)
P.S. Yes, coil will fire irrespective of fouled plug.
You could always swap plug/wire/coils around to see if the timing light results change...
However, if it ran fine for a week and progressively got worse even after you swapped wires, that sounds like fouled O2's - that suspicion is made even more likely with the open headers/rich tune.
Have you scanned the car for misfires and O2 voltages ? Pulled the plugs to look at them ?
Rob (Bad30th)
P.S. Yes, coil will fire irrespective of fouled plug.
The plugs are black but other than that they don't look fouled. The car ran with NO o2's installed at all for about a week. And reinstalling them didn't make the problem go away.
How did you run your car with no O2's ? You mean without REAR O2's, correct ? The front ones are used for fueling calculations, rears are only to measure cat efficiency. I am talking about fouled FRONT O2's.
...if the plugs are black/sooty, they ARE fouled... Running a rich tune with open headers will foul plugs and O2's quick.
Fouled O2's will not cause 2 cylinders not to fire, I'm not sure why your timing light test results are wierd...
I'd get a scan tool and see what cylinders are really misfiring, if any, and take a look at the FRONT O2 voltages.
Any SES lights ?
Rob (Bad30th)
...if the plugs are black/sooty, they ARE fouled... Running a rich tune with open headers will foul plugs and O2's quick.
Fouled O2's will not cause 2 cylinders not to fire, I'm not sure why your timing light test results are wierd...
I'd get a scan tool and see what cylinders are really misfiring, if any, and take a look at the FRONT O2 voltages.
Any SES lights ?
Rob (Bad30th)
I mean no front and no rear o2's for one week while I waited on the front o2 extensions to come in.. The rear ones are deleted in the tune. If black sooty plugs mean they are fouled then that's the problem, but it still doesn't make since why the coil isn't firing.
Yes the SES light in on. I bought all new plugs today and will swap those soon and see if that fixes the problem or not.
Yes the SES light in on. I bought all new plugs today and will swap those soon and see if that fixes the problem or not.
Well, think of it this way... a spark plug simply completes a circuit from the coil, through the plug wire and then across the spark plug electrode. If your plugs are fouled, you are not completing the circuit, hence not getting a spark on those cylinders.
If you ran more than a minute or two with out O2s and a ypipe, you car started running pig rich and will foul out the plugs in no time.
Change out the plugs, disconnect the battery for an hour to reset the pcm, and you should be alright.
If you ran more than a minute or two with out O2s and a ypipe, you car started running pig rich and will foul out the plugs in no time.
Change out the plugs, disconnect the battery for an hour to reset the pcm, and you should be alright.
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I did the same thing. I installed a cam, headers and a ypipe and i didnt have O2 extentions for a month. Well I was told by the guy that tunned my car (local guy) that I was retarded and to put those O2's (front) back in ASAP! So I did. (PS. The car ran fine without the front O2's) After I put them back in, I changed the plugs and drove home to houston (350 miles) to my tunner to get the cars first and only tune. Well on the way, about 50 miles out, my car started shaking, my car was blowing black smoke out the tailpipes. My SES light was flashing. After going to autozone, my code was Muti- misfires. Well after the tune, i was on my way back, and it still does it. I have no clue to what it is. I am not trying to hi-jack your tread, I think our cars have alittle in common. Oh and i also changed wires to MSD. Still no go
Mike
Mike
