ankurdave

While troubleshooting a different problem, I was able to induce a surging idle by mis-adjusting the throttle position sensor by putting it at either extreme of its range while the throttle was accidentally propped open. I'm not sure how fast the IACV can move, but it would have to be pretty fast to be responsible for the surging in my case. My guess was that the ECU was varying the fuel mixture. Maybe in your case the IACV was reporting its position incorrectly, causing the ECU to get confused in a similar way.

sancarlos1

300 miles since changing the IACV. Mostly city stop and go and no idle problems. Hopefully it is fixed. Hard to diagnose IACV problems of this nature. No codes, and the newer valves cannot be opened up for inspection. The coolant hose to the IACV is difficult to remove and replace making replacement a little difficult without removing the plug wires. My suggestion is if you have a sudden idle problem that includes a high idle when hot and in drive (1100 rpm) that surges up to 1500 and back to 1100 in park that comes and goes, with no codes. find a used IACV and make the swap.

python

iTrader: (4)

hope u fixed it...when my alternator went out it started surging