spark problem?

[dan280zx]

Have a 1983 280zx turbo. Car starts and idles fine when cold. After it warms up it misses at idle. Something is causing the spark to cut in and out as the engine is running. Using a timing light to see when it fires, it will fire a few times then miss one or two times and then sort of repeat this over and over. To make this even stranger each of the 6 plugs seem to have a different rhythmn. Some fire almost all the time, some are firing about half the time. I need some help! This is what has been done.

Compression check-------all near 150 lbs.

New cap and rotor.

New plug wires.

New plugs.

Tried a new coil--no change.

Checked connections at the dizzy.

Checked AFM, throttle switch, engine temp sending unit--all ok

Had the control unit out to test sensors and wiring back to it. all the connections looked good.

I have a fsm, but its not helping me though this.

[dan280zx]

Found out today that engine is missing also when cold. Checked a bunch of ground connections and connections at the transister. all seemed ok. Need some help. This is starting to make me look a little less smart in the eyes of my 16 year old son.

[dadydover]

try checking the distibutor pick up this will be under the rotor also check the distributor shaft itself eitherone can cause the pickup timing to fluctuate and cause a missfire also check your fuel system this can fool you into thinking its an ignition missfire

good luck

[ZmeFly]

Here are some of them

Faulty spark plugs

Moisture in cap blah blah

Shorts in ignition, or the plug wires

Clogged fuel filter

Vacum leaks at the intake or at hosse connections

Clogged pcv

Dont always look at the obvious, there are many things that could make you have this problem.

[dan280zx]

Put a scope on the ignition coil low voltage side. Was getting pulses of voltage with no misses. Put another new cap and rotor on. Engine started and ran pefectly. (no misses) Then I sped engine up, when the turbo spooled up ,got a bunch of smoke and the engine started to miss again. Plugs look oil fouled.

Is it common for the turbo to leak into the intake and foul the plugs?

Is there any "cheap way" to keep the plugs from fouling out. I put Bosch platinum plugs in when we bought the car a few months ago. I've read somewhere that some swear by the NKC plugs that were original.

If it comes to a turbo repair/replace situation what is the best place to go?

Thanks for the help!

[dan280zx]

Forgot to include this. The guy before me had put on some antifoulers before installing the plugs. They were about 3/4" long and I guess they keep the plug away from the oil. Could this be a "cheap fix" for this situation?

Not tring to be cheap about this, but it's my son's car and his money is limmited.

[dan280zx]

I think it is starting to make a little sense. I know now that my main problem is ignition. (turbo may be tired but new clues have surfaced.) Car is now running with good spark on 2,4,5,6 plugs. 1 and 3 get a spark about 10% of the time. I verifid that if was not the condition of the plug by leaving the plug in the engine, unhooking the wire and putting a screwdriver in the end and allowing it to spark to the frame of the car. 1 and 3 only get spark once in a while.

Going to do some research if someone else has had this problem. My guess is that the distributor has a problem. I'm open to any suggestions on what to do next.

[ZmeFly]

I would be saving for a new turbo soon.