I have a 92 Accord EXR (Canada) 2 door, M/T.

My car was recently cursed with the dreaded "Surging Idle" problem. Mine is from idle to 3000 and back constantly. Cold or Hot engine.

I have done the searches and read alot of good posts. I have a brother with a 93 LX who does not have this idle problem. I swapped out both the Idle Air Control Valve AND the Fast Idle Thermo Valve (Keeping them joined with the coolant line between them) from his car to mine. It did not change anything. I swapped his control box (Black plastic box containing MAP Sensor, Purge Cut-Off Solenoid Valve, EGR Solenoid Valve, and CVC Valve) for mine but the surging idle remains.

There is one thing I can do to relieve the engine from surging. If you remove the black intake tube from the TPS port you can feel 2 medium sized ports inside. If you were to position yourself to face the TPS, one port would be at approx. 8 O'clock and the second port would be around 10 O'clock.

While the car is idling (Surging) with the black plastic tube removed from the TPS I plug the 8 O'clock port with my finger and consequently the car stalls.

I start the car again but this time I plug the 10 O'clock port with my finger the car calms down and idles fine. Keeping this port plugged I obviously can't drive around to see how it drives but I can rev the engine and it reacts perfectly. RPMS rise without hesitation and return to a normal idle just below 1000RPM.

I can only assume my problem is a vacuum leak on the intake system. My question is where to look first and how best to isolate and find the leak. I have used a certain method in the past to find vacuum leaks with much success. All I will say is when you find the leak with this method the idle rises. I just don't know if I should mention it or not so I won't.

What vacuum lines are tied to that 10 O'clock intake port. Where can I start looking?

I just did a tune up of Cap, Rotor, Spark Plugs, Oil + Filter, Air Filter and Topped Off Coolant with system bleed.

Thanks.

 

I'm not familiar with the 92, but if the car was warm, the 8 o'clock position would be the idle air control valve. This opens when the car is at normal operating temp. The 10 o'clock is the fast idle valve which should not be bypassing air when the enging is warm.

I just replaced my fast idle valve on my 95 which kept my idle surging. It created a vacuum leak and my idle was fluxuating. After my new valve was in there, I started the car and the engine roared @ 3000 rpm. I thought that I was screwed. After unplugging some sensors on the intake, the idle went back to normal. After starting the car back up, the idle was stuck @ 3000 again. I reset the ECU by pulling the backup fuse (7.5 amp) under my hood. After that the idle was fine. I think that the car had to 'relearn' the idle settings. Maybe not resetting your ECU screwed things up.

On the 95 model, you can tighen the fast idle valve by first removing the valve, open up the case, and tighten the screw. I posted a couple of links with pictures. Reset your ECU after installation.

http://honda-tech.com/zerothread?id=699787

http://honda-tech.com/zerothread?id=1564019

Good Luck

 

Hi PAhonda. I wish it was as easy as changing the Fast Idle Valve. I posted that I had swapped the two valves out from my brother Accord who's car does not have the idle problem. I did this to try to pinpoint the problem rather than spending unnecessary money.

I had forgotten to mention that I had some brake lines changed. There is some type of brake line junction on the passenger side right near the firewall/control box of the car. Are there any vacuum lines in that vacinity that may be linked to the Idle Air Control? Maybe one of them got damaged during the brake line replacement.

I did find a stray vacuum hose stuck between the hood and cowl. I don't know how long it has been there but the garage insists they didn't put it there. I traced all over the engine looking for an unplugged vacuum inlet/outlet and I also compared vacuum lines to my brothers but found no difference.

 

at the end of the throttle body,, left side next to the brake master cylinder, there is what is called the air boost valve,,,,,,it has a cover with 3 phillip screws just like the fast idle valve,, i have seen those leak and cause the same issue you are having

remove the cover and chk it out

 

deserthonda,

I can remove the cover but what am I looking for when I do?

 

after you swap out sensors be sure you reset your ecu too... (if you already did that sorry I missed it in the posts....) Under that cover to start with I'd do a visual inspection and then see if there is anything abnormal about it (leaks etc), as far as specific test procedures I'm no good there....

 

Your throttle body is somewhat different from mine.

This image might help identify some of the vacuum routing around the throttle body. #9 to 23 is the vacuum routing for the air boost valve. Maybe disconnect #11 from the ABV and plug the valve to see if it idle settles. Would indicate valve problem. Then disconnect tubing in order to find vacuum leak along that line. You can also try from # 8 back to the intake tube.

 

I actually did not reset the computer after trying my brother's IACV/FITV assembly. Is it necessary to reset after ever valve swap so to speak?

 

Yes. Reset the ECU.

 

what was the number printed on that 'stray' vacum line?
This whole thread sounds like it's leading to a vacum leak somewhere.
Have you checked the big vacum hose going to the brake booster? Pinch that big sucker and see if the idle changes.