THIS IS JUST STUPID. 93 SI 4WS, SURGES AT IDLE, RUNS MINT OTHER THAN THAT, NO VAC LEAKS, MAP WORKS FINE. I HAVE BEEN A TECH FOR YEARS, HAVE A SNAP ON SCANNER, ALL PARABLES FINE, ONLY THE DUTY CYCLE IS FLIPPING OUT. HAS ANYONE HAD THIS PROBLEM?

 

As weird as this may sound but my car did the same thing. I found out the coolant was low. Once I filled it up, it ran fine. Worth giving it a shot.

 

Im sorry would you mine explaining what serging means. If its what I think it is (the motr is reving itself) I had that happen to me the other day and my coolant was low as well, but I think its a vaccum line right next the EGR valve was capped off. I filled coolant up and un capped the vaccum line and it stopped reving itself. (Im a noob)

 

IACV? Taking mine off and cleaning it out with brakleen worked like a charm to stop idle surge. EGR valve or purge solenoid malfunction can also cause this.

 

this may sound stupid but check you powersteering fluid level itruns through the trans. and can cause a surging idle if it gets too low/ alsoiacv