99 4runner idles really low

[TSP-MIKE]

Got a 99 4runner and the idle is really low. Anyone have any suggestions.

Thanks, Mike

 

[Thai]

How low?? What RPM is it when starting cold?? Any surges in the engine noise?? Do you mis-starts??

As long as your engine warms up properly and runs fine, then i would not worry about it.

 

[TSP-MIKE]

It idles at around 400 Rpm. Even when warmed it still does it. It does surge but not all the time. Sometime it'll just idle really low, and sometimes it will idle better but surge. I have a fuel Press Guage hooked up to it and at 41 Psi it'll idle really low but when it drops to like 34 Psi it runs fine but dies in like 5 secs.

 

[Thai]

Here are some suggestions:

- Clogged fuel filter? Clogged fuel injectors? Dirty throttle body?

- How many miles on the O2 sensor? Owners manual recommends change ever 80K miles. O2 sensor is about $100.

- If you have not already done so, replace the fuel filter even though you have good pressure. Fuel filter about $20.

- I've read that the wiring to the injectors on 2nd gen 4runners may have bad crimp connections in the harness. With the truck running, try wiggling each injector connections and work your way down the harness. If you get a miss in a certain section of harness, check and repair that sections. Could it happen to your 3rd gen 4runner??

- Try cleaning the throttle body; if that doesn't work your idle air control motor could be bad.

Basically, if you can take your truck to a good mechanic, then do it and have them check these things out.

Good Luck!

 

[TSP-MIKE]

Thanks for the help. I found out that the computer didn't get out of start mode so it always ran rich which caused it to idle low!

Mike