In march of last year, I garaged my 98 civic lx (d16y7) and went on an 8 month deplyment to the middle east. I got back in october of last year and from the moment that I started it up, the idle has been going between 800 and 2000. I have been trying to figure it out ever since. It throws out a P0505 code (IAC) so I replaced the IAC, but even with the brand new IAC, it does the same thing. I have made sure that all my vacuum hoses are connected. I have replaced the primary o2 sensor as well. Any suggestions? BTW, is it true that air bubbles in the coolant can cause this condition?

 

Is you car giving any CELs???

 

yea, it's throwing a P0505 (code 14) for the IAC

 

Update...I took off my tb to check the gasket, which was in good condition. I noticed, however, that where the tb meets the im, there is a space not covered with gasket, which just so happens to be right underneath the iac valve. So I made my own "gasket extension" if you will and now the car runs fine. No cel, no idle problem. What confuses me is that I looked at a brand new gasket from advanced auto and it too doesn't have the extra piece, so I guess what I'm saying is...how did I fix it? Can I expect any negative side effects from what I did? Has anyone ever heard of a similar problem?

 

Kinda weird to read that you let your car sit. I did too before I had the idle problem. Except mine only sat for a month but I would start it up at least once a week for good will. Glad to hear you fixed your problem.

I have a couple ?'s for you:
1) what is a TB and what is an IM?
2) What exactly did you do to fill the gasket gap? I ll do the same if it'll let me drive the car around.
3) Have you had any side effects since repairing the gasket?

Thanks in advance for any advice you can give me!

s.