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Bunyon & Babe
February 15th, 2013, 09:50 PM
This is a bizare question ; but first a bit of background . The idle on our Toy ( 4 runner , 88 v6 ) pulses as if you were gently increasing and then letting off the throttle . It goes up about 100 rpms every 2 - 3 seconds all by it self . I thought it might be the thermostat but today noticed something strange . While sitting at a stop light I noticed the idle only pulses while my foot is on the brake . If I take my foot off the brake it stops going up and down . It's a standard and the clutch is all the way down.
Any ideas ??????? Thanks

Hypoid
February 15th, 2013, 10:21 PM
Are the brakes vacuum assist?

Metalhed
February 15th, 2013, 10:24 PM
Check Yotatech.com
This is a problem with air box, if I remember right

dr350jja
February 15th, 2013, 11:26 PM
Make sure no vacuum leaks. With the engine running, you can spray some carb cleaner around the vacuum hoses and connections, to see if the idle increases. May help identify a leak.

4Runninfun
February 16th, 2013, 12:25 AM
If this pulsing only occurs while your foot is on the brake, and assuming you don't have a vacuum leak then might be this:

in our trucks when you push the brake it send a fuel cut-off signal to the ECM when your RPM is above ~1200. While you are stopped if you idle is set high enough it will be affected and will pulse between ~800 RPM and ~1200 RPM. Set you idle a little slower and you should solve your problem.

Bunyon & Babe
March 3rd, 2013, 09:31 AM
Thanks Guys !!! Really apreciate the advice on this !!