Idle problem after high altitude trip

[alfredo25r]

Hi, please I need some advice. I have a 94 JDM H22A Honda Prelude. Until saturday my car was fine, Idle was at 800 RPM but yesterday I went to a trip to a city located at high altitude, when I got there the idle was crazy it goes from 1500 RPM to 3000 RPM, I thought It will be fixed after going back to my home town but nothing, it is the same, I have tried to reset the ECU and reset the idle but nothing works the idle keeps like crazy.

I have stage 2 brian crower cams, p28 ECU tuned with crome.

Please somebody help me.

Thank you!

[spiffyguido]

Does the idle fluctuate? When you say 1500rpm to 3000rpm, do you mean that the idle surges between those two values, or does it hold steady?

[alfredo25r]

Hi, yes it surges between those two values. Exactly it goes from 1000 to 2000 RPM. Here is a video I have uploaded to youtube where you can see the problem.

http://www.youtube.com/watch?v=klOSWm-dvfY

Thank you.

[alfredo25r]

Also I have discovered that if I turn the ligths on the idle stays at 2000 RPM and it don't surges anymore.

[spiffyguido]

Nearly always, fluctuating idle problems are caused by a faulty Fast Idle Valve (Idle Air Control valve). In many cases, the valve itself is fine, but the coolant has run down and there is a bubble of air stuck in the valve causing it to work incorrectly. I'd try bleeding your coolant according to the service manual to see if that helps. It's possible some air might have snuck into the coolant lines during your trip. Is the coolant reservoir topped up?

[RedRacer]

Could also be that the FIT valve has worked it's way out of seat from the factory placement and the springs isn't in place where it needs to be and is creating a vacuum leak which is causing the up and down idle.

The process I am going to recommend is exactly the same as what is detailed in this AWESOME write up from SUPERHONDA.COM. Please note I am giving them ALL credit for their forum article.

Superhonda.com member Cautela has taken a lot of time and effort to make this super-great write-up, complete with imagery, etc. to help fix what I bet is your problem.

Check this link on their site and definitely give them props for the write-up if it helps you out.

http://www.superhonda.com/forum/f55/tro ... ms-259965/

I'm just too lazy right now to go into the detail that he has.

~ RR

[alfredo25r]

Nearly always, fluctuating idle problems are caused by a faulty Fast Idle Valve (Idle Air Control valve). In many cases, the valve itself is fine, but the coolant has run down and there is a bubble of air stuck in the valve causing it to work incorrectly. I'd try bleeding your coolant according to the service manual to see if that helps. It's possible some air might have snuck into the coolant lines during your trip. Is the coolant reservoir topped up?

Thanks, I will check the IAC Valve, I hope it is ok because in my contry there are not replacements for this car. I will bleed the coolant. The reservoir tank is not topped it is half.

Could also be that the FIT valve has worked it's way out of seat from the factory placement and the springs isn't in place where it needs to be and is creating a vacuum leak which is causing the up and down idle.

The process I am going to recommend is exactly the same as what is detailed in this AWESOME write up from SUPERHONDA.COM. Please note I am giving them ALL credit for their forum article.

Superhonda.com member Cautela has taken a lot of time and effort to make this super-great write-up, complete with imagery, etc. to help fix what I bet is your problem.

Check this link on their site and definitely give them props for the write-up if it helps you out.

http://www.superhonda.com/forum/f55/tro ... ms-259965/

I'm just too lazy right now to go into the detail that he has.

~ RR

Thanks man I will also check the FIT valve, thats an awesome write up, I will follow the steps, I hope it fixes the problem.

[alfredo25r]

Problem solved. It was the intake manifold gasket. I've changed it and problem solved.

Thanks for the help.

[RedRacer]

Glad you got your problem resolved.

Thanks for letting us know what the upshot was.

Curious though, what led to the diagnosis of the gasket? How did you come to learn that was the problem?

[alfredo25r]

Glad you got your problem resolved.

Thanks for letting us know what the upshot was.

Curious though, what led to the diagnosis of the gasket? How did you come to learn that was the problem?

Sorry for the delay, I thought this post was closed. First I did what spiffyguido told me an also what you told me to do but those things were Ok, so I decided to disassemble the intake manifold, and there was the problem, the intake manifold gastket was broken. Thanks for all the help.

[RedRacer]

Ah! Ok, that's great to know. Thanks for the follow up and glad you got it working right.

No problems since you made the repair?

[alfredo25r]

Since the repair I have no problems with idle , but since 2 days ago I have a little problem with the clutch, everytime I push the cluth theres is a sound like a bird or something like that.

[RedRacer]

Uh oh. Bad throwout/release bearing. Not such a bad thing, especially if you are able to do transmission repair work yourself.

You can drive it until it stops working, or you can fix it now. At this point I'd suggest going on and replacing all the major components, and check the rear seal and make sure there are no leaks from the engine onto the clutch plate. Good time to replace that too if you have any leakage. If you've got questions though, just post them in a new topic window.... I don't want a good transmission thread to be missed because we started talking about it under your FIT failure topic.

[spiffyguido]

Also a good chance to swap out the axle seals.

[alfredo25r]

Uh oh. Bad throwout/release bearing. Not such a bad thing, especially if you are able to do transmission repair work yourself.

You can drive it until it stops working, or you can fix it now. At this point I'd suggest going on and replacing all the major components, and check the rear seal and make sure there are no leaks from the engine onto the clutch plate. Good time to replace that too if you have any leakage. If you've got questions though, just post them in a new topic window.... I don't want a good transmission thread to be missed because we started talking about it under your FIT failure topic.

Ok, I will start a new topic, thanks for the help.

Also a good chance to swap out the axle seals.

Thank you, I will look for that replacements.