: Idle at 3000 RPM HELP!!!

11-10-09, 11:27 AM
Hello everyone,

Last week i repalaced the brakelines of my 1993 sts 4.6l northstar.
After the repair i have start the engine and i went straight to the 3000 RPM. It would not stop so i turned it of and looked around. Nothing strange that i have seen before. The next day i have cleand out the trottlevalve with intake cleaner it still wasn't over. But when i started the engin it wil go to about 2200 RPM. But when i toch the pedal once it will stay on 3000 RPM again. When it is rotating at 3000 RPM the trottlevalve is fully closed.

I allready pulled out the code's but nothing has come up.
What could be the problem or what can i check? I can't drive like this. When i am driving it wil drive about 90 km/h without me touching the gas.

Much thanks in advance.

11-10-09, 01:59 PM
Start looking for a serious vacuum leak. Something is letting in way too much air past the throttle body. Verify that all the hoses and fittngs on top of the engine are in place and not cracked or loose.

Edit: I see that you have a 1993 STS. The cover on top of your engine is part of the intake manifold, make sure that it is on properly and sealing correctly.

11-10-09, 05:23 PM
I agree. IF the throttle plate is "FULLY" closed, the engine would stall. If that is the case you do have a serious leak somewhere that should be pretty easy to find with some Brakleen.

11-10-09, 05:37 PM

Also check the fat vacuum line going to the brake booster (since you were messing with the brakes).

11-12-09, 12:09 PM
Thanks for the help. I will check tommorow if i have a vaccum leak and if the the cover plate is closing of properly.
I will report tommorow.

Much thanks allready

11-13-09, 07:05 AM
Hello everyone,

I've found my problem!!! It was the ISC that was keeping open the trottle valve. It was only opend for maybe 1 or 2 milimeters but is was enough though. I think we hit the brace of the unit and there for it moved towards the the trottle valve. There is a small bolt on top op the ISC and we turned it in. Now it is idling at 900 RPM.

11-13-09, 11:17 AM
Keep going - you want the idle at 650 - 675 in D.

11-13-09, 05:47 PM
Press on the bolt until it retracts. Then pull the plug. Now adjust the plunger to a .060 gap to the throttle lever.