So my idle has been getting progressively worse for the last two weeks but i just can't stand it anymore. it started with a high idle after i would come to a stoplight which would return to normal if i tapped the gas. A few days later the idle was still steady but was at 1500 RPM. This week the idle is now high and races back and fourth from 1500-1800 RPM. The weird thing is that if i turn on the headlights, the bouncing rpm stops and it stays at 1500. On startup the engine goes through the normal warm-up routine but never works its way back down... and when its up to opperating temp. develops the strange jumping idle. Otherwise the engine behaves normally when in gear. Anyone run into this problem before? Any advice would be awsome. I have checked the vaccume lines for cracks/leaks and everything seems ok there but I may have missed something.
Also, (if i cant seem to fix it by friday) would this jumping idle be likely to damage anything else if i were to take the car on a 5hr/way drive??? I hope not... Thanks guys

 

My car had a very similar problem that turned out to be the wax "thermistor" that raises the idle when the coolant is cold. There is a small cam on the back side of the throttle body that presses against a 1/4" rod. The housing that holds this rod has coolant passages that sometimes get clogged, unfortunately mine was not clogged, just broken.

The other symptom I had was that you could "pull" the idle down with the clutch at stoplights and it would stay low, even after you put the clutch back in. Otherwise it would either bounce or just stay high if the electrical load was on. Not sure why this worked given the nature of the problem (throttle blade opened by the wax rod) but it all went away with the thermistor fixed.

Find the cam and push it against the thermistor and see if the idle changes (with the car hot, it's pretty solid when it's cold)

Good luck,

Alex

 

Unfortunately the fast idle cam is not to blame. Any other suggestions?? I'm not sure what to check next.....

 

Does the idle change when you press and depress the clutch?

Check that. If so, check the clutch switch as it's been the cause of many idle problems for people.

 

Well it doesn't seem to be the clutch switch either... idle stays the same with clutch depressed. I am stumped!! I really can't understand the jumping idle... is the ECU trying to compensate for some strange flucuating sensor reading that is changing w/ engine speed. Im not sure what else to check =(

 

Try this thread:

https://www.rx7club.com/forum/showth...hreadid=170731