Hi-
I love my 95 4runner, but it's been a bit of a pain lately.

Last year I was experiencing some low idle problems and after an
adjustment and throttle body cleaning, the low idle disappeared but was
replaced by an erratic up & down idle whenever the AC was on. Jumped
from 500 to 1500rpm every few seconds.

It was only while the AC was on, which I rarely use, so I ignored it
(bad idea). Now the erratic idle happens intermittently, especially
when cold, with or without the AC. Also, soon after the erratic idle
reappeared, I've developed a hesitation in 5th gear when accelerating.
Do you think these things are related?

I've heard that this is not super-rare among these trucks. Any ideas
about what could be causing it?

Thanks in advance
Scott
(90 4runner 22re, 95 4runner 22re)

 

There are two different valves that could be causing your problems. First, the A/C idle up. It revs the idle a bit when the A/C is on. It is adjusted by a screw that's sort of betwee the intake and the valve cover.

The second problem could be a clogged/faulty cold air idle up valve. This valve bumps the idle speed when the engine is cold, and then it shuts itself off once the engine warms up. The one on my '94 was clogged and it caused the idle to run too high. When I stepped on the brakes it would trigger the fuel cut to the injectors, and the idle would bounce between 1000 and 1200 rmp.

I guess a third possibility is a dirty/faulty throttle position sensor.