Within the past 2-3 weeks, I've noticed that my car idles between 600-950 RPM--almost to the point of the engine cutting off. I'm worried of the worst--blown head gasket or piston rings. I will do a compression test soon to rule this out (or not).

Has anyone had this problem before? I don't know if this is an ignition issue or a sign of a more serious engine problem.

Can you smooth it out with your power tuner? If not, I'd suspect the plug wires first. Watch your timing with a datalogger. If it's all over the place at idle (-5 to +20) like an o2 signal, it's probably the wires. That's what mine was anyways...

I'd say either a problem with your ignition or fuel. Check your wires and plugs first, I bet that's the prob.

Idle Air Control vavle..check it out.. of course, i will say do a compression test also :)

I don't know what's going on. This morning the car idled roughly (rpm fluctuates up and down), then when I got home this evening the car idled very normal--it held steady at 900 RPM.

Jay Curcillo has an extra IAC. I'm gonna swap that one in just to see what happens. Also, I will do a compression test this weekend (I'm not too anxious about that though).

Everything else is good: coil, spark plugs, cables. No blow-by. Normal oil consumption. I'll keep checking. Thanks, and keep the ideas coming guys!

Do you get any CEL's? Do you have the EGR blocked off by chance? When my car's ecu does the EGR test, it closes off the IAC, and looks for the airflow from the EGR. Well i have the egr blocked off, and when the ecu does this test, my car will idle like crap, almost ready to die out. Every time it does this, it throws that EGR insufficient code CEL, so i know its that. Just thought i throw that out at ya..Also, by rough idle, do you mean jerky, stalling out idle, or just rpm fluctuation, like it doenst stay still? I'm still thinking its your IAC, but who knows..

>>>Jay Curcillo has an extra IAC. I'm gonna swap that one in just to see what happens.<<<

Man since I am so close to your house I need to test that extra IAC sometime if that's ok. I have the same problem as you :(

Matt Bush, when you get a chance, just email me.

I e-mailed you through the 2GNT mail.

Check the Idle Air Control Valve on the TB

Where on the TB is the Air Idle Control Valve?

IAC is on the firewall side of the TB, kind of at the bottom side of it. You cant miss it.

iac= bottom side of tb.. its the big guy...


Michael 99gs
HRC Stage 2
Stage 3 process begins anyone got a 420a block thats not spun/head for sale?

http://www.dreamwater.net/purplebeast

I finally found the problem--by accident :) I jacked up the car to relocate my FPR and fuel line hoses, and found that a vacuum line goes from the intake manifold to the (EGR accumulator box?) the black box behind the intake manifold was just dangling there.

Also, I saw my O2 sensor wire was pinched (it was crushed) under my upper strut t-b mounting plate; and I had just put this on about two weeks ago--when the intermitten idle problem began. It was either one or a combination of the above that caused my idle problem.

I appreciate everyone's tips and suggestions. However, I'm still going to do that compression test. It's too soon to tell now, but the car seems to idle fine.