1999 Accord LX Coupe
2.3L F23A1
5 sp manual
196K miles


Background: When driving my car and up-shifting into any gear the idle hangs for a split second after pressing in the clutch and sometimes even goes up 100 rpms or so. Unless I wait for the RPMs to come down its hard to drive the car smoothly/enjoyably, and it just becomes really annoying when driving up hills when I need to avoid loosing speed by shifting quick. If I have to accelerate to high RPMS (red-line) in traffic, while shifting I literally have to slowly count "one-one-thousand" before letting the clutch out before the RPMS drop to where they're supposed to be and I can re-engage the clutch. I've had several manual cars and never had a problem like this.

That said, nothing else is wrong with the car. No surging idle, high idle, etc.

I have a long 100 mile commute every day and this idle/shifting thing has been driving me mad.

I've read almost every thread I could find about this subject and have tried nearly every solution that applies to 6th Gen Accords including:
-Adjusting the clutch pedal in both directions
-Adjusting the clutch pedal sensors in both directions (thinking they might have some affect on the idle hanging when the ECU doesn't know the position of the clutch)
-Removing and thoroughly cleaning the IACV
-Checking for Vacuum leaks on vacuum hoses and the upper/lower intake gaskets
-Cleaning the Throttle Body and associated sensors
-etc... etc..

Most of the time when driving my idle hangs when shifting; however at totally random times when driving the idle will drop quickly like it should and I can drive normally with no issues. It only acts normal for a little while before going back to the normal hanging idle issue.

It seems as if this is either an ECU issue or an IACV issue, being it's at time intermittent nature and that nothing else is wrong. I'm leaning more towards the IACV being the culprit as it is original, but has anyone else ever had the problem and corrected it ?? I just want to check before dropping $100 on a new IACV

Anyone else have a suggestion or opinion on this?

 

Sometimes IACV's tend to stick when dirty. Carbon will build up in them and cause unsteady idle. A new IACV from Honda is about $230.00 which IMO is absolutely ridiculous, here try cleaning it. https://honda-tech.com/forums/acura-integra-6/%2A%2A%2Ahow-clean%2A%2A%2A-your-iacv-k-idle-air-control-valve-1575913/

 

...I already very thoroughly cleaned my IACV as indicated in my list above. Actually, I cleaned it twice and the issue still remains.

Rockauto has IACV valves for $130ish new, and there is a seller on ebay that has them for $85 new, however I'm hesitant go aftermarket for such critical parts.

 

Try cleaning the FITV. That controls air flow to the engine while its cold and the bell on the end likes to vibrate out. Here is a nice write up on it. https://honda-tech.com/forums/acura-integra-6/%2A%2A%2A-how-%2A%2A%2A-clean-your-fitv-aka-fast-idle-thermo-valve-1564019/ We used this write up on my buddys h22 and it took care of this idle hang like your talking as well as some other rough idle issues. Its worth a try and only takes about 20 min.

 

How did you clean it? When I did mine I used PB blaster and filled both chambers completely and let it sit for about two hours. Then drained what I could and used an air gun to blow the rest out.

 

F23a1 doesn't have the FITV from what I understand, that was changed in 1998 from what I read. Different setup.


I removed it from the intake and filled both chambers with carb cleaner, let sit for a while, emptied out, then cleaned with q-tips. I did this several times until the small rotory valve was shiny clean and moved freely. Trust me it was clean, I'm crazy about details and I didn't want to do it again (even though I did to check away).

 

yes you are correct. I apologize i miss read the specs on your car.

EDIT: did you check the spring condition on the TB when you cleaned it? it may be hanging up before it fully closes when you let of the pedal.

 

I would check the throttle cable and throttle body spring for smooth operation. The butterfly could even be sticking.

 

I'm the same, I have a surging idle problem currently that I've had no results in fixing. I cleaned both (one from a junkyard) till they were absolutely spotless.

 

That was one of the first things I did. TB isn't sticking I've had it off and cleaned it thoroughly, and cleaned it multiple times afterwards. When operating the TB with my hand it moves freely and snaps shut as its supposed to.

This is what I mean, I've already exhausted almost every solution.

 

Have someone press the gas and you watch the tb. it could be something in the cable sticking. It might not hurt to get some cable grease and lube up your throttle cable.

 

I lubed up the cable and checked the grommet, it isnt sticking on anything.

The TB snaps closed just as it is supposed to also.

I tried a new IACV on it also, but it didn't really seem to make a difference. It wasn't OEM honda though.

 

Check out these videos and you can see what is going on:



Also, I read that the base idle could affect this and to unplug the IACV with the car warmed up and adjsut the idle to 550rpms to set it correctly. However when I unplug the IACV the idle bounces a small amount (see video below). Is this normal when adjusting the base idle?

 

check all your vacuum lines. that idle bounce sounds like a vacuum leak

 

does sounds like a vacuum leak

 

I’ve just bought an 01 accord with the same issue. Did you ever find out what the issue was?

 

I never found a vacuum leak or figured out the issue unfortunately.. and no longer have the car.