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Discussion Starter #1
anyone know where the adjuster is located? my idle is sitting at 5-600rpm. sometimes it fluctuates between 500 and 1300. sometimes it'll stay at like 800rpm. thanks
 

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Supafly
1991 toyota pickup
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4,401 Posts
MAke sure you have no leaks in your intake. Spray propane (unlit torch) around the intake, if it idles up, its leaking). If there are any leaks you will have idle problems.

The idle screw is a big flathead screw on the TB, staring at you when you look at it from the front of the truck.
 

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You might pull the air hose off the front of the throttle body and see if the throttle plate (butterfly valve) and the rest of the throttle body could use some cleaning. Gummed-up throttle bodies can cause rough idle.

Use a throttle body-specific cleaner, not a carb cleaner, and be careful not to get any on the throttle position sensor (the black plastic thing on the side of the TB), as solvents may damage it. A toothbrush will help you get the back of the throttle plate, and a clean rag will help, too. Be sure to give several good shots of the cleaner in the upper and lower air bypass holes that are just in front of the throttle plate. FYI, the upper passage is for your hot idle - that's the one adjusted by the screw. The lower is the cold idle bypass, controlled by the "auxiliary air valve" below the throttle plate that closes when hot coolant hits it.

If your idle is still uncontrolled after checking for vacuum leaks, cleaning the throttle body and adjusting the idle screw, you will want to check the throttle position sensor (tps). Two of the four terminals are supposed to have continuity when the throttle is closed (idle position). That tells the computer the throttle is at idle. If IDL and E2 don't have continuity at idle, you can try adjusting the position of the sensor, but if you can't get continuity on those terminals, the sensor must be replaced before the motor will run right. There are specs and procedures in the factory manual. If you don't have one, google 1993 toyota pickup service manual. There's additional info on checking the tps and specs for the older model 3VZE's here:

http://www.toyotanation.com/forum/showthread.php?p=2624069#post2624069
 
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