# Misfire/jumpy idle, need input



## luvzcars66 (Sep 18, 2005)

hey asleep, im looking at buying an `86 z31 and as iv`e already posted, (and Zen kindly replied to) that it`s got an idling issue. They guy said he`s reset the ECU, put in a new MAF, new distributor, and TPS...the only thing left to change (i think) is the coil. Any ideas and advice on installing one? anybody?


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## Zen31ZR (Mar 24, 2004)

luvzcars66 said:


> hey asleep, im looking at buying an `86 z31 and as iv`e already posted, (and Zen kindly replied to) that it`s got an idling issue. They guy said he`s reset the ECU, put in a new MAF, new distributor, and TPS...the only thing left to change (i think) is the coil. Any ideas and advice on installing one? anybody?


 Coil install is pretty basic, I wouldn't sweat it. Just make sure the ignition is off when you do it.


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## luvzcars66 (Sep 18, 2005)

Zen31ZR said:


> Coil install is pretty basic, I wouldn't sweat it. Just make sure the ignition is off when you do it.


You think that could be a possible culprit? Sounds kinda like it when he says "humid" and "wet" weather is when its the worst...its not even really an idling issue after driving the car. You can feather the accelerator(in neutral) up to about 2200 rpm, and then it bounces between 2200 and about 1000. Acts kinda like a rev-limiter...or you can mat it, it jumps to about 3000, then bounces between 1000 and 3000...puzzling...


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## Zen31ZR (Mar 24, 2004)

luvzcars66 said:


> You think that could be a possible culprit? Sounds kinda like it when he says "humid" and "wet" weather is when its the worst...its not even really an idling issue after driving the car. You can feather the accelerator(in neutral) up to about 2200 rpm, and then it bounces between 2200 and about 1000. Acts kinda like a rev-limiter...or you can mat it, it jumps to about 3000, then bounces between 1000 and 3000...puzzling...


Plug gap might be too big and the coil is getting maxxed out. Check all of them. I'm gonna move this to it's own thread so we can get more input.


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## AZ-ZBum (Nov 21, 2004)

have you tried anything as basic as a simple tune up?

plugs
wires
cap
rotor
etc.


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## Zen31ZR (Mar 24, 2004)

I'm taking it from the gist of the starting point that the car is not his yet. He should ask the owner that, though, yes. 

I'm thinking it could also be the o2 sensor.....


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## Marc Z31 (Jul 25, 2004)

luvzcars66 said:


> You think that could be a possible culprit? Sounds kinda like it when he says "humid" and "wet" weather is when its the worst...its not even really an idling issue after driving the car. You can feather the accelerator(in neutral) up to about 2200 rpm, and then it bounces between 2200 and about 1000. Acts kinda like a rev-limiter...or you can mat it, it jumps to about 3000, then bounces between 1000 and 3000...puzzling...


Without a doubt in my mind, that is a bad maf, or it is not connected correctly. The engine will cut fuel at 2000 RPM with the MAF sensor unplugged. Try unplugging the MAF and start the car... If it runs exactly the same, you know what is wrong.


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