RPMS acting odd! help!

[colins323]

hmmm OK when I come to a stop light or to a stop from moving while in gear, I put the clutch and put it in neutral and when the RPMS drop they dip so low that the car ALMOST stalls! it has stalled once while this went on! but after it dips down to like 200rpm it comes back up and sort of moves up and down between 600 and 800 rpms and doesnt stay still! anyone got a clue what it is!

I checked the vaccum lines, and I noticed that my A/F guage will sit at rich for about 10 seconds when this is happening then it will go back and forth as usual!

[D323]

IACV (idle air control valve) needs cleaning. Sadly, that is usually a vacuum issue problem.

There have been a few threads about this problem, and the usual fix is finding a vacuum leak.

[colins323]

boooo for me

[91ProtegeLX]

also check to see if your intake hose is cracked/broken.....I had the same problem and thats what mine ended up being.

[MazKid]

Mine did the same thing...I figured it was my RX-7 AFM so I retuned it and it's fine now. I looked for vacuum/intake leaks and found none...my dad even brought out a propane canister and blew propane all around the intake/vacuum lines and no difference at all.

[beetle_orange]

sounds like what our infamous Z5 does all the time.

[Natural]

Mine does the exact same thing, though it's more of a problem in warm weather. Been too lazy to take the intake apart to check it, but I probably should before winter hits. Oddly enough it's only a problem when I let the clutch out in neutral. If I push the clutch pedal back in and put it in gear the idle returns to 750-ish.