At first it was really bad, idling up to about 3500 and back down. the cold idle valve was stuck wide open. I was able to fix that, and it got a lot better. Now it idles fine whent it's cold but goes from about 1200-1500rpm after its warmed up. Sometimes it stays at about 1500rpm. I took the IACV off and soaked it in solvent to remove the carbon, and then blew it out with an air nozzle but it made no difference. I also checked all the vacuum lines one by one to make sure they were not leaking. I made sure the coolant reservoir was full. the TPS sensor reads a solid .505v with the throttle closed. what else could be causing this problem? it's driving me nuts. any help would be greatly appreciated.

 

I have the same problem. When im at a light my car will start reving to about 1500 then drop and does it for a while. I cant figure it out.

 

Try this - start car - let it do it's idle surge, pop hood, unplug IACV plug - does the surging stop? If so, try adjusting your throttle body idle set screw clockwise.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hondaaccordvtec &raquo;</TD></TR><TR><TD CLASS="quote">Try this - start car - let it do it's idle surge, pop hood, unplug IACV plug - does the surging stop? If so, try adjusting your throttle body idle set screw clockwise.

</TD></TR></TABLE> Yeah, do this first....He's talking about the screw on top of the throttle body. NOT the set screw for the throttle plates. You never adjust the bottom screw.


Don't just check the overflow tank. You need to check the radiator, too. A low coolant level will cause the same problem (low enough that the coolant temp sensor is exposed to an air pocket).


Remove the air intake duct from the throttle body. There should be 2 ports visible. The top port is for the idle adjust screw and thermo valve. The lower port is for the IAC valve. Plug one port at a time. Does it quit surging? Does the engine stall?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hondaaccordvtec &raquo;</TD></TR><TR><TD CLASS="quote">does the surging stop? If so, try adjusting your throttle body idle set screw clockwise.</TD></TR></TABLE>


mine did this and i can turn the screw all the way shut and id dont do jack!

 

cleaning out the idle air control valve does not ALWAYS work. You might need to replace yours with a NEW one. Also, do not open the base idle screw too much! Maybe one to two complete revolutions.

 

cool you guys are awesome. Thanks so much for the advice. I checked the radiator too, but I didnt purge the air out of the system. I'm going to try that too. I was about to try a new map sensor, but I guess I won't need to do that. last question, is the idle adjustment screw the one that is covered with that gray goop? I scraped the crud off it and tried adjusting it and it had no effect on the surging.

 

Bleed air screw on top of the throttle body should only be adjusted w/ the ICV disconnected. Otherwise the idle control may compensate for bleed air changes. Idle should be 600 +/- 50 rpm w/ ICV disconnected. Reconnect and reset ECU.

good luck

 

i have this same problem also...when i start the car the idle is at 800 but when it warms up to normal temp it idles at 1500. can somebody please give me some steps to fix this. i replaced the iacv with another used one and its still doing it.

 

If your idle surges up and down when engine is warm, then there are two posibilities:

1) throttle position sensor is bad
2) map sensor is bad

 

If your idle surges up and down when engine is warm, then there are two posibilities:

1) throttle position sensor is bad
2) map sensor is bad

 

I bet all it is is the idle screw. I had the same problem a week ago. I turned the screw clockwise 1 trun and bam it was fixed