I have a 99 Honda accord 4 cyc F23A4(ULEV) . I just recently had a P0401 code . I replace the EGR valve . Code was reset and returned . So I cleaned the plentum port (it was clogged) going to the egr valve with carb cleaner. Replaced the gasket to the plentum intake manifold and put everything back together. Started the engine and now in rev's from 1000 rpm's to 2000 rpm's constantly. Does anyone have any ideas of what might be the cause or what I need to check.

 

possibly your air intake sensors

 

Its a vacuum leak. Look for a disconected or broken line. Look at the lines going to the intake especially where you worked on it.

 

that makes more sense
lol

 

x2 on vacuum leak!

Did you make sure all of the old gasket was completely removed before you put it back together with the new gasket?

 

Well, I tried spraying carb cleaner around all vacuum hoses and intake manifold. Couldn't find vacuum leak. I want to say that I did clean the old gasket using the carb cleaner. I guess the only alternative is to remove intake manifold again to verify. Thanks for everyone's help. All advice is appreciated.

 

There's your problem, you needed to use some sandpaper on it to remove ALL of the gasket material. You also need a razor blade too, that gasket material is SUPER stubborn to remove.

 

Well, I just removed the plenum intake manifold again and cleaned with fine sandpaper. Reinstalled everything and still getting the idle from 1000k to 2000k at idle. It has coded a P0505 and p0113. Any ideas?

 

Did you diligently inspect the gasket surfaces? Take a good look at them, you should only see shiny aluminum. Use your hand to feel the surfaces as well.

I'm sorry that it didn't fix it, this time inspect the vacuum hoses individually, maybe one is disconnected. Spraying carb cleaner is not always the best way, especially if you don't know where all the vacuum lines are and where the intake is.

 

Mishako129 I appreciate all your help. After taking the Plenum back off and checking the surfaces which they did look clean. I decided to still use some very fine sandpaper over the surfaces on intake and plenum. Reinstalled every thing .Vacuum hoses also look good and checked for leaks. I removed the intake hose going to the intake , There is a small hole inside the intake throttle body going the Intake Air Control Valve. I used my finger to cover up the hole after I started the engine. After doing that the engine idle stalled. The idle should drop or stall letting me know that I didn't have a vacuum leak. If it does not there is a vacuum leak present. After all of this the FIX.
SOLUTION : IAC (IDLE AIR CONTROL VALVE). Picked up a new one from Autozone for $165. I also found some on Ebay between $50 - $82 . But didn't want to wait 4 days to get it. Thanks again
Hope this helps someone in the future .

 

Glad to hear that you got it figured out.

Did you try cleaning your rotary air control valve (RACV) before you replaced it? A surging idle with a dirty IACV or FITV (both combined in the RACV on the F23A4) is a very common issue with Accords... However, you didn't mention that you were having any surging idle issues prior to cleaning your EGR.

There is a really good DIY in the FAQ on how to clean these valves as well as the entire intake and throttle body. The F23 isn't designed exactly the same as the engine in the DIY. but the process for cleaning everything is the same.

 

GhostAccord, no it didn't start surging until after I cleaned the EGR port and Plenum and installed a new plenum gasket. Thats what 's weird. No problems previously at all. I'll checkout the DIY's on the intake and throttle body. Thanks also for your previous posts. Take care

 

Cheers