For some reason my 97 4runner is running at 2500 rpm's at idle. I checked the coolant temperature sensor and the IAC and they both are checking out fine. The linkage and the throttle body were a little dirty. A Toyota mechanic has told me that the IAC is probably the cause. But I just want to make sure, before I buy another one.
Since you have not mentioned a check engine light, I'll assume that there is none, so the components that control idle will check out electrically.
How did you check out the coolant temperature sensor and IAC?
If you have not already done so, remove the IAC from the throttle body and clean it with carb cleaner as it may be sticking.
Also check for cracks, holes, or gaps in the black plastic snorkel between the air filter housing and throttle body.
The idle stays at 2500 rpm's and the linkage is not sticking..
Correct there was no check engine light.
I have removed the IAC and it appears to opening closing smoothly.. A Toyota mechanic told me that cleaning does no good.
"Ray O" ...
Stupid Tomes question - what is this IAC? Tomes
IMHO, questions are never stupid the first time, like when I asked a friend what the difference between a hook and a slice was in golf. ;-)
The Idle Air Control ("IAC") is a valve that controls engine idle speed when the throttle plate is completely closed. When the throttle plate is completely closed, the engine still needs some air to run at idle, so the IAC valve allows some air to bypass the closed throttle plate. The IAC valve opens and closes to maintain idle speed.
Over time, the throttle plate, the rod that the throttle plate pivots on, and the IAC become coated with a sticky gummy film which can make the throttle plate stick closed and the IAC stick.
The gummy film comes from engine crankcase gases, which gets vented out through the positive crankcase ventilation (PCV) valve into the engine intake system to be burned. The problem is that some of the stuff in the crankcase gas settles in the throttle body, throttle plate, and IAC valve.
Cleaning the IAC valve does not always work, but I think that it is worth the effort since cleaning it costs less than replacing it, and problems sometimes clear up for a while. If the problem clears up after cleaning, even temporarily, you will know that the IAC valve is the culprit.
While you have everything taken apart and still have the carburetor cleaner out, also check the throttle plate inside the throttle body to make sure it closes all the way. If the throttle plate and inside of the throttle body are not silver and have taken on a varnished appearance, spray the inside of the throttle body with carburetor cleaner and wipe out the residue. Open up the throttle plate and clean the back side of the plate, paying attention to the edges of the plate where it contacts the throttle body and where the pivot rod passes through the throttle body.
"Ray O" ...
Thanks Ray for the detail. I get it now. Tomes
You're welcome! Any time!
Yeah because if it IS the problem and you clean it -- you save yourself $300-400. Trust me -- I replaced one and I am almost confident it didn't need done.
On that note -- same w/ your MAF. They're supposedly self cleaning but I find cleaning mine every oil change is helpful as it's always dirty each time I have checked and they're expensive to replace as well.
On that note -- same w/ your MAF. They're supposedly self cleaning but I find cleaning mine every oil change is helpful as it's always dirty each time I have checked and they're expensive to replace as well.
********** I would not clean the MAF sensor that often. The hot wire is pretty thin, and if you damage it, the MAF sensor is toast. Also, constantly unplugging the harness from the MAF sensor can loosen the contacts in the plug or receptacle.MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.