High Idle Problem


BRONCOIIREDNECK

10+ Year Member

Joined
Dec 10, 2009
Messages
1
Points
3,001
Vehicle Year
1990
Transmission
Manual
I HAVE A 90 BRONCO II I PURCHASED AFTER IT HAD BEEN SITTING FOR 7 YRS IN A BARN. THE GUY THOUGHT THE ENGINE WAS BLOWN BUT ALL IT WAS WHERE BLOWN FREEZE PLUGS AND A CRACKED HEAD. I HAVE BEEN FROM EXHAUST TO FUEL INJECTION AND REPLACED MOST OF IT. SHE IS RUNNING LIKE A CHAMP NOW BUT I HAVE AN IDLE PROBLEM. WHEN I PUSH IN THE CLUTCH COMING TO A STOP THE IDLE JUMPS TO BOUT 2500 UNTIL I COME TO A COMPLETE STOP THEN DROPS TO 1200. I CANT GET IT DOWN TO 900 WHERE IT SHOULD BE. IT HAS BEEN SUGGESTED THE IDLE CONTROL VALVE IS BAD. ALSO WHEN DRIVING IN 2ND AND 3RD AND JUST COASTING WITHOUT MY FOOT IN IT, THERE IS ALOT OF JERKING LIKE SHE WANTS TO STALL. ANY IDEAS WHAT THIS COULD BE?:sad:
 
Check your vaccum lines. One of them maybe cracked or disconnected. You can also try cleaning the IAC, to see if that helps.
 
When your absolutely sure there are no vacuum leaks keep checking because there sneaky and hard to find.After you take everything apart its real easy to miss one.
 
+3 on the vaccum leak, my 90' has a habit of doing this and it always ends up being a cracked vaccum cap or hard plastic line leaking. you can use starting fluid to test for a leak, the engine will idle up higher when you spray the leak.
 
I would also bet it's a vacuum leak.

And turn your caps lock off.
 
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