# `86 idling issue...



## luvzcars66 (Sep 18, 2005)

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Hi everyone, I`m a noob in need of some help. I`m looking at buying an `86 300zx. The car is in awesome condition inside and out, but the owner tells me he`s had an idling issue. He says the car tends to cut-out and miss at about 3000 rpm, especially in humid or wet weather. He said he`s replaced the ECM, the throttle position sensor, and something else I cant remember, but apparently he`s spent quite a bit of bank trying to remedy the problem, with no luck. If anyone has any ideas, please let me know as I would really like to feel good about buying this car.
Thanks
Er, I said 3000 rpms, cuz thats what he said, but I`m thinkin maybe he meant 300...?


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## Zen31ZR (Mar 24, 2004)

It shouldn't be idling as low as 300 rpm anyway. The VG30 _can_ idle that low, but it shouldn't normally. So he must be talking about 3000 rpm. Coincidently, that is where the ECU switchs the injectors to the batch fire formation. It's possible both ECUs are damaged and weren't making the transition properly. I beleive the MAF can also be a culprit in this situation.


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## luvzcars66 (Sep 18, 2005)

okay cool. I`ll look into that a little further...p.s. there are TWO ECU`s???


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## Zen31ZR (Mar 24, 2004)

luvzcars66 said:


> okay cool. I`ll look into that a little further...p.s. there are TWO ECU`s???


Sorry, didn't mean to confuse you. I just mean that the ECU that was replaced, as well as the replacement ECU, possibly was damaged.


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## luvzcars66 (Sep 18, 2005)

gotcha...ok thanks again...I`ll see what I can find out...


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## nissandrew (Aug 23, 2005)

Zen31ZR said:


> Coincidently, that is where the ECU switchs the injectors to the batch fire formation.


Is that why my car pulls hard at 3000 rpms?


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## asleepz (Feb 24, 2004)

It's very close to peak torque... Are you turboed? If you are, that where full STOCK boost should be in.


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## Xorti7 (Dec 27, 2004)

asleepz said:


> It's very close to peak torque... Are you turboed? If you are, that where full STOCK boost should be in.


Is it different for the t25's?


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## Zen31ZR (Mar 24, 2004)

Xorti7 said:


> Is it different for the t25's?


The T25s only saving factor is that it spools up quicker than the T3, gives the engine more low end and thus the illusion of a bigger engine. Spoolup to full boost is probably still between 2000 and 2500 rpm. 

I'd be looking for a boost leak as well, anything between the turbo and the throttle plates. The rubber connectors can crack, and you won't notice even by a visual inspection, but the crack will pop open under boost, and make the engine run like heck due to the difference between the air measured by the MAF and the air that actually gets into the engine. Might also check all the plug wires and the coil wire. They are a weak point.


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