Well for the last month or so I have been getting a 100-150 rpm surge about every 3-5 seconds at idle in park. wether the car is cold or warmed up. My opti is about 1 yr. old, plugs/wires/lifters/pcv about a week old. 02's about 7 months old. and seem to be switching fine on my scanner. going into closed loop also. car seems to be running strong. not breaking up. showing alittle rich at idle on my scanner, but I believe it is overlap from the cc306 cam. actually when I pulled all 8 plugs to put in the new ones, they were more white than beige. almost like a lean condition. I do have the lower rpm surge when cruising from the cam. but car does not break up runs strong thru the rpm ranges.. no codes. so at a loss any ideas? oh yeah walbro 255 fp. kirbin afpr. and autometer electric fp gauge.does not seem to be dipping or dropping when car is surging. also fuel filter is about 8 months old... just at a loss?

 

ttt...anyone?
could it be the IAC? It is original.

 

Could be it's sticking.

 

Thanks Bret I' replace it, and see how that helps.

 

You could need a new IAC or just clean that one. Don't know but that COULD be the problem.

 

I did clean it about 6 months. ago. I'll try that again first... thanks..

 

Put it on a scanner and see what the IAC counts are doing. As well as some other read outs. Wouldn't hurt to check actual engine vacuum levels as well.

 

well Im pulling around 10-11" of vacuum at idle, I heard about normal for the cam Im running. no vacuum leaks, I just replaced the lifters. and the intake is sealed up tighter than a drum. and all new vacuum lines.

on my scanner Iac counts is about 47-50 counts. fluctuating at idle. when cruising down the highway around 2700 rpms counts are around 116...