Abdias Sanchez

Hi Everyone,

I recently got a '03 Civic and have been going through the car doing all the maintenance I can. This weekend I cleaned the IAT and MAP sensors. After turning the car on I got a CEL for the IAT so I checked the connection, re-plugged it in, and cleared the code. After restarting the car, the light went away but there is this weird revving that happens after I let off the gas. The car idles amazingly well after (around 750-760) but every time I let off the gas, not matter how much gas i give it, it revs to about 1900 rpms for a second and then comes back down. Any ideas?

Thanks.

GusBuz

Try doing an Idle relearn. Use the search bar here in the forum to look for the procedure.

Abdias Sanchez

Thanks for the response. Yes I did this yesterday. Warmed up the car up, unplugged the battery for a bit, plugged it back in, started the car with no accessories on for 10 minutes, turned the car off, turned it on again and drove a bit. Do I need to drive it more for the ECU to relearn?

Abdias Sanchez

Bump

Abdias Sanchez

Update: I re-cleaned the throttle body this time by taking it out completely and also cleaned the IAT and MAP sensors again. Started up just fine but still has the surge after I let go of the gas. BUT, today I noticed that it doesn't happen when the A/C is on. Now I'm really confused. Any advice?

Zed

Maybe ezone can shed some light, but it sounds like maybe the previous owner has adjusted the throttle cable shorter and it's causing the revs to climb, the ecu however knows the revs should be around 750rpms or so, and is adjusting it down after it climbs as you described.

Wankenstein

What cleaner did you use on the IAT and MAP?
Did you just disconnect them and clean connnections or did you remove both sensors completely and clean the insides?

Abdias Sanchez

Thanks for your replies guys. I found it! There was a vacuum leak. Looks like it was always there and the ECU had learned to compensate for the extra air coming in. When I reset it I guess it unlearned it. I capped it off with some tape and did an idle relearn. Now it's fine. Anyone know if there is supposed to be a hose there? Or is there a tiny rubber cover I can put on there? It's a small nipple on the driver side of the intake manifold.

NDNV

Post a picture of this nipple you are referring to.
Here is a diagram if you want to use it to identify the nipple you are referring to.
Chances are there should be no disconnected connections on the intake...

NDNV

Here is the diagram of the intake manifold. http://parts.sonshonda.com/showAssem...rimLevel=24777

Abdias Sanchez

Thanks for the diagram. I've looked up pictures and part #19 on that diagram is the cap that is missing on the nipple.

Abdias Sanchez

Just for reference: If you look at this thread, https://www.civicforums.com/forums/3...ng-belt-2.html , the very last post has an upside down picture of the nipple capped off. And if you read, he actually had the same exact problems that I did. I'll go to the dealer and buy that nipple today. Thanks a lot!