95 Cobra high idle

BarnStang

Founding Member
Mar 2, 2001
1,260
3
39
Hagerstown, MD
I posted this in 5.0 tech. Didn't know there was a seperate forum for 94-95. Can anyone help with some info on this problem?

Car idled at 2100 rpm when I started on it. First, this car is a little different. Last year, the 95 computer was ditched cause it would not idle at all. It has a computer out of an 89 GT manual trans. It also has a bigger cam in it but am still trying to find out which one. Doesn't sound very radical but it won't idle so.. its also got a BBK CAI on it. Stock MAF, stock TB.

Cleaned the IAC, TB, and MAF, and EGR. EGR operates normally and is closed at idle. I got the idle down to 1500 using the base idle adjustment proceedure-computer reset, remove IAC harness, start car and set base idle. Could not get it below 1400. Car off reconnect IAC start with no load for 2 min, off and back on with everything turned on for 2 min. The base idle adjustment screw is off the stop. THe throttle blade is as closed as it can get.

It starts high at 2000 rpm then drops to 1200-1500 but takes a good 45sec to 1 min to drop. Taking the IAC harness off now has little change as it should. TPS is .980 exactly.

One interesting thing I found. If I pull the MAF harness off it idles perfectly. Jumps right back up when the MAF is reconnected.

I haven't checked the 10 pins or the O2 heaters yet.

I would like to know a list of grounds specifically for the 95 Cobra so I can check all that. I suspect they are pretty much the same as my 93 but want to make sure. I couldn't see any ground from the intake to the firewall.

It seems that unmetered air is getting in but I sprayed the front and back of the intake and where the upper attaches and all over the throttle body and CAI. No change in engine speed at all. Seems tight.
 
If you have the throttle stop all the way off, and the idle air bypass screw closed all the way, and it still idles high, then your IAC valve is likely bad.

First thing though, get a vacuum gauge, and check to see how many inches of water column you have. If you have a vacuum leak, this will be a symptom.

Get a new one a pepboys. You want the borg/warner one. All others will not work, as I have dealt with this before and tried everyone. The borg/warner one will look exactly like the factory one.
Scott