Questions and Answers

Toyota 4-Runner Hunting Idle Q. Hi Vincent Ciulla, I have a strange idling problem but maybe you have experienced it and can diagnose the problem. My 1987 Toyota 4-Runner 22RE fuel-injected engine has a irregular idle [high-low-high-low like a bad EGR valve] ONLY when the brake pedal is depressed in 2WD.

The idle remains smooth if 4WD is engaged and the brake pedal is depressed. I disconnected the brake, master cylinder vacuum line and plugged it with the engine idling, and the high-low idle still happened when I depressed the brake pedal.

The EGR valve seems to be working, the engine code is 1, normal, and I replaced the oxygen sensor and all the ignition wires and spark plugs. I also removed the towing electrical harness thinking the isolator could be malfunctioning and connecting the brake lights to the turn signals, but the problem idle still occurs. Any help you can give will be appreciated.

Thanks,
Joddy
Chattanooga, Tennessee

A. Okay, since you say you got a code 1 then it's pretty safe to assume it is a mechanical problem and not an electrical problem.

I like to look for the simple solutions to a problem like this because the answer usually is a simple one. SO I would recommend giving the throttle body and Idle Air Control Valve a good cleaning. I wrote an article on this that will help you. Cleaning Throttle Bodies

If after cleaning you still have the problem, we can go from there.