93 Grand Prix - very high idle

Hello,

At start up my car will shoot to about 3000 rpm and idle at that speed for awhile. I am guessing the EGR valve will need to be checked/replaced. Is there anything else that I should also consider to fix the idle. They problem is really annoying.

Thanks

Jon

Reply to
Jon Sobieralski via CarKB.com
Loading thread data ...

What engine is in it? 3.4 DOHC v-6 perhaps? If so, these often developed a vacuum leak at the intake manifold gasket. This would cause a high idle condition.

Ian

Reply to
shiden_kai

yep. it's a 3.4. If it is a cooler day it will idle real high. On hotter days it will idle normal at start up.

Reply to
Jon Sobieralski via CarKB.com

They were famous for the lower intake manifold gasket developing a vacuum leak. I think that would be good place to start.

Ian

Reply to
shiden_kai

What do you think about re-torquing the manifold bolts to see if it helps before going the trouble of replacing gaskets? It seemed to help on my 3.1.

Reply to
Scott Buchanan

Thanks Ian, I'll just go ahead and replace the gasket. Hope it works. If not I will come to you for advice.

Jon

Reply to
Jon Sobieralski via CarKB.com

I'll give that a try first. That would be nice if that was the problem but I am thinking it is more than that. We'll see.

Reply to
Jon Sobieralski via CarKB.com

Why don't you try a little diagnostic work before you replace the gasket? Get something like brake cleen or a carb spray cleaner and see if you can locate the vacuum leak. Spray it around the intake area and see if you notice any change in rpm/running...etc.

Ian

Reply to
shiden_kai

Not a bad idea, but on the 3.4 DOHC engine, the lower intake gasket consists of a metal plate with the ports surrounded by raised rubber ribs. The gasket is designed to be "squished" and the bolts that hold the intake in place usually don't lose their torque. What I've observed is that one of the gaskets around a port will become separated from the metal plate and gets sucked in toward the port area causing a vacuum leak.

Ian

Reply to
shiden_kai

Nifty idea, I'll try that after work today or tomorrow.

I'll keep ya posted

Jon

Reply to
Jon Sobieralski via CarKB.com

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.