Idle Troubleshooting I have a 1996 Toyota Carib 4wd that I have just put a replacement motor in. Intake with injectors & distributer I left in the bay while I changed motors. Now on the new motor it revs to 1200 at idle & I can't get them down. If I bring the timing to 8 or 10 Before TDC it revs even higher and is only lower when it is way after TDC. Any ideas gratefully received. THANKS

SOURCE: 94 blazer vortec 4.3 idle revs up and dont come down

check your Throttle Positioning sensor that should fix your rough idle the TPS controls the breather on the front of the engine its affixed to the right hand side of the throttle body just infront of the spyder on the V6 Vortec 4.3L Models

SOURCE: Truck idles rough but at

Give it a complete tune-up, New spark plug and wire.new Ignition coil. Depending on the engine either replace ,Cap and rotors or coil packs.Also might want to get the fuel injectors service

autodr

• 260 Answers
• Posted on Dec 01, 2008

SOURCE: At idle the engine revs up and down

engine lite on? would ck to make sure there is plenty of coolant in system. low coolant may cause idle hunting. also could have a vacuum leak or air intake restriction. ck air filter

SOURCE: 95 GMC Jimmy 4.3l W vin rough idle

My problem was solved when I repaired my 4 wd activation dash switch. The switch was contacting on 2WD & 4HI at the same time. The front differential activation is vacuum activated possibly creating a tug of war that didn't actually engage it but drained off vacuum from the engine? A theory at best but stumbbled across it because I knew the switch wasn't working properly I repaired it and low and behold rough idle disappeared and all is good for 3 weeks running.

SOURCE: idle problem: motor revs up and down at idle

it sounds like your idle control valve needs cleaning or replacing