Z34lumina

I have a Z34 Lumina with the 3.4F/I. When I start the car sometimes it High Idles up to about 3,000 RPM about 30 seconds later it goes back down to about 1,000 RPM. I took it to a GM shop they told me it was ether the computer or a vacum motor on the throttle body. Please help me.

kip123

yes that can be true, the idle postion sensor can be dirty that can cuase that to happen you can remove the sensor and clean it with carb cleaner or throttle body cleaner and that should do the trick.. however if you still get it one thing to look at is your intake gaskets but when they leak they tend ot idle high for longer periods of time

www.calgarystreetrides.ca

Z34lumina

When i first took it up there about 6 months ago they also couldnt find out what was wrong and they said that they took a gas and ran it along the intake and they said it foulded out and said that i might need a new gasket but they told me that it had nothing to do with the high idle problem. I was wondering about that and thanks for the help.

RollinonZ34

I would bet my last Dollar that it is the Lower Intake Manifold Gasket!!!

I just changed mine "same motor but a 94 Z34 and it did the trick. Idles like new. A good sign of it being the Lower IM Gasket is that it does it worse in the morning especially when it is cold outside, and does not do it as bad or at all, once it is warmed up...as the motor heats up it expands filling in the leak. Usually when you bring a car into the shop with these symptoms, their first reaction is to change the IAC, and this does not take care of the problem. As far as being told to clean IAC with carb cleaner...i heard that this might damage it! Not sure tho cause i am not a mechanic, just a heads up to be gentle with it if you take it out...don't push the pentle around, as this will also damage it.