high Idle
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Joined: Mar 2003
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high Idle
Hello,
Just a quick question, I have a 91x w/ 136,000 miles on it.
The engine was rebuilt, new shocks, ball joints, locking hubs, brakes, fresh tune up/ oil change , alt, recently replaced the IAC Valve. The truck runs and drives great, except one thing, My idle definitly seems to high . It idles around 1500- 1800 rpm. My friend has the same truck and his is at about 800 rpm, and seems to run much smoother. is there any easy way to lower the idle that I can do?? somebody told me about adjusting the stop plate screw, but someting needs to be unplugged while you are doing that, and I dont know what. I also dont know which way to turn the screw if this is the case. I also cleaned the MAF thinking it might be that.. Thanks to everyone in advance, Rob
Just a quick question, I have a 91x w/ 136,000 miles on it.
The engine was rebuilt, new shocks, ball joints, locking hubs, brakes, fresh tune up/ oil change , alt, recently replaced the IAC Valve. The truck runs and drives great, except one thing, My idle definitly seems to high . It idles around 1500- 1800 rpm. My friend has the same truck and his is at about 800 rpm, and seems to run much smoother. is there any easy way to lower the idle that I can do?? somebody told me about adjusting the stop plate screw, but someting needs to be unplugged while you are doing that, and I dont know what. I also dont know which way to turn the screw if this is the case. I also cleaned the MAF thinking it might be that.. Thanks to everyone in advance, Rob
Junior User
Joined: Dec 2003
Posts: 61
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From: Louisville, KY
I had this problem too. I adjusted the stop plate screw and it solved the problem. like you, i had no clue about doing this, but jsut guess and check... turn it a little one way and see if it raises or lowers the RPM. if it raises it, turn the screw the other way. I froget which way i had to turn mine, sorry. good luck!
Posting Guru
Joined: Aug 2000
Posts: 1,984
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Rob, the throttle stop screw adjustment could indeed be off, since the engine's been rebuilt. The procedure is to first unplug the IAC and start the engine. The engine should run at a very slow idle, almost at a stall. Adjust the stop screw until it does idle very slowly (around 400-450 rpm). Then replug the IAC. The IAC should then pick up the idle to a normal range, 700-800 rpm.
The adjustment you make might throw off the TPS voltage. You can check it with a voltmeter; do a search for the procedure. Basically you are looking for a reading of .96v on the signal wire when the throttle is closed and the key on.
The adjustment you make might throw off the TPS voltage. You can check it with a voltmeter; do a search for the procedure. Basically you are looking for a reading of .96v on the signal wire when the throttle is closed and the key on.
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