96 Z34 Rough Start & Idle for a few minutes

[Telebender]

I just purchased a 96 Z34 from a friend of mine. When the car is cold and I start it really has a rough idle. It even dies out a couple times before it continues to run. This is without me hitting the gas at all. Once it does start and continue to run it idles very rough and goes back and forth from 2000 RPM to around 800 RPM. After a couple minutes of it doing these strange cycles it does smooth out and seems to run fine.

I'm looking for any advice anyone may have out there....

Thanks

[jw67]

i would check the coolant temp Sensor. what the does is control the fuel acording to the temp that it reads. if the Sensor is bad and it reads...say 90 when it is really 40 out it will not have the right air fuel mix and run like crap untill it warms up.



PS..the temp Sensor that works you temp gauge/light is not the same sensor. so your gauge/ligh will not read hot/cold

[CEO Wrench]

Originally Posted by Telebender

I just purchased a 96 Z34 from a friend of mine. When the car is cold and I start it really has a rough idle. It even dies out a couple times before it continues to run. This is without me hitting the gas at all. Once it does start and continue to run it idles very rough and goes back and forth from 2000 RPM to around 800 RPM. After a couple minutes of it doing these strange cycles it does smooth out and seems to run fine.

I'm looking for any advice anyone may have out there....

Thanks

Had this problem on 2 Monte Z-34s - it's usually the lower intake manifold gasket. Check other threads and I think you'll find that's usually what it is.

[stock03GT(fornow)]

Telebender ... did you get your problem figured out?? I have the same issue in a 95 Z34.

[ulies8]

I have the same problem i changed the upper intake gasket tuned her up changed the ECM computer, air idling control valve, cam shaft sensor and she still idles when i stop at a red light to the point that she almost cuts off frustrating please help.

[CEO Wrench]

You said you changed the upper intake gasket, right? Usually, the problem is the lower intake gasket.

[dr olds]

you have to change the lower and upper intakes, the lower is the one that goes because it is plastic and rubber, the rubber seals crush down and over time either get brittle or hard and create a leak. also whike you are there under the lower intake there is a aluminum plate it is an oil gallery plate, but it also is a vacuum source, change that too, it is only avail. from the dealer and it is only 10.00. cheap insurane while you are already there. make sure you also change the water o-ring under the throttle body once you remove the intake they are junk. i can give you a step by step if you are doing it yourself, the job is not that bad, it took me about 3-4 hours with air tools.