In June I purchase an 02 4runner with 34000 miles on it. (mint condition) SR5.
The question I have is when running the heater at idle, is it normal for the engine to (surge) a little. The surging is intermittant. (maybe 15 second intervals)

Any help would useful

thank you

 

Are you running the heat in defrost mode?
.....because if you are then the AC will be cycling to dry the air (and there's your engine surge).

 

Yeah Im running the defrost


That should explain it.


Thanks for your help.

 

welcome to yotatech wow 35k miles sounds like its a real nice 4runner

 

This idling issue has happened to me as well. But wouldn't the AC button have to be depressed for the compressor to dry the air?

Forgive my ignorance of my '02's AC system.

 

Nope, as soon as you set it to "defrost" the system automatically turns on the AC to dry the air (whether you like it or not). I don't remember if the AC button lights up or not in defrost mode, but just about every modern car will do this. Pop the hood and you should be able to hear the AC kicking on and off and the idle increases when the AC is on.

 

I have a 94 4 runner and I have a idle problem. Sometimes it runs at a fast idle 12,000 rpms and on other days its eratic. While stopping the idle will jump up and down. It seems to have started when i blew a bypass hose for the coolant, which was right by the throttle body. I cleaned the throttle body and checked for vaccum leaks and so far I haven't solved the problem.

 

If you cleaned your throttle body with fluid, the fluid can effect the TPS. Check this link to 4crawler.com


Taken from http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

 

i have just solved a similar problem on 92 22re the coolant lines goin to the tb were plugged with rusty sludge i also cleaned the throttle body off the truck and checked my iac valve located inside the tb .if you remove the iac valve count the turns i didnt and now it idles slow on cold cycle ,although much less annoing than surgeing idle its not perfect. idling high can also cause these symtoms try to adjust down with the air adjust screw the big screw on the top pass side of tb. if those things dont help the coolant temp sensor causes wacky stuff when it goes bad. i also did a seafoam treatment using the bigger vacum line just before the tb .the total effect was no more surging and big mpg improvement

 

When all fails. Disconnect the battery (negative, it's safer). Re-connect after a few minites. This will reset the computer.