My Prelude has recently started rev'n up and then dropping down. Usually it's when it's warm, but rarely when it's cold. I think it's either the Air Charge Sensor or the MAP Sensor. If anyone knows or has any suggestions please let me know.

Thanks

 

First check your coolant level. Then I would check the intake manifold for any leaky hoses.

 

Intake Air Control Valve or Fast Idle Thermo Valve. One or the other, almost guaranteed, is going bad.

Read more here.

 

^^^ yup, thats exactly what it is. I cannot remember which one is affected when the coolant temp. is warm though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by maxvtec7500 &raquo;</TD></TR><TR><TD CLASS="quote">^^^ yup, thats exactly what it is. I cannot remember which one is affected when the coolant temp. is warm though.</TD></TR></TABLE>
It's supposed to be the IACV, but it could honestly be either one. Mine was doing it only when cold originally (which indicates the FITV), but then began doing it all the time. Based on that, I thought it was the IACV, but changing the FITV solved it.

Edit to say that I did the FITV because it was quite a bit cheaper, and it happened to solve the problem. In the case of the original poster here, I'd recommend pulling both the IACV and FITV and cleaning them out thoroughly before buying anything.

 

So I should clean them first before purchasing a new one? Do you remember how much they were? And I'd probably have to go to a Honda dealership to get them wouldn't I?

 

Yes, take 'em off and clean them first. IACV is over $200, but the FITV was $72 + next day shipping charge. Cleaning the carbon out could help, and it's free (aside from the cost of some cleaner).

You might be able to find a used one at a local yard, but it's doubtful (I've never found an H22 at a yard here in Utah, anyway).

Yes, you'll probably want to go to Honda. Check around first to be safe, but I remember that the IACV was actually cheaper from Honda than any of the big four parts-houses (AZ, Checker, Pep Boys, or NAPA). Can't remember on the FITV, but the fact that I bought it from Honda indicates something.

 

same thing happened to my h23...iacv

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93boostedLUDE &raquo;</TD></TR><TR><TD CLASS="quote">same thing happened to my h23...iacv</TD></TR></TABLE>
same here iacv cleaning it solved the problem

 

What if you have the same symptoms, but have both valves (FITV-IACV) are bypassed with no vac leaks or air bubbles in the coolant.

 

And how should I go about cleaning them...like what should I use and how did you do yours?

 

Personally, I used soap and water. A solvent or cleaner of some sort would probably be great.

 

its a idle air control valve, not intake air control valve, but usually when its warm and it starts reving up and down its the fitv, the plunger needs to be turned in