When the car is moving, as in above 5mph, the car will idle at about 1600-1700 constantly when the clutch is engaged, or the gearbox is in nuetral. But as soon as I come to a stop, the car will drop to normal idle (~700).

Before the car would idle at about 1000-1100 in the same circumstances as above.

I have been searching for the last hour trying to find any sort of a vacum leak, havn't found any sign of one.

Is there some little trick or secret that anybody can help me out with, or any experience with this problem?

Any help is greatly appreciated...

BTW: Yesterday is when it started, and it started after I replaced the TPS sensor and IAT sensor. They were both broken and throwing CEL's. Now there are no more CEL's and the TPS and IAT sensor appear to be working fine. I just can't find a link between the new parts and a high idle while the car is moving. I might be overlooking something, so I'm asking for your help ...

 

Bump

I had the same problem before, i would like to know what it is...

 

For sum reason honda's will serge like that.........I see it a lot when you are sitting still at a light or the car is still cold.

That is all i got.............anyother opinions. I don't think it is a problem!

 

Well...I don't drive the car until the temp needle is at least 1/8 up the gauge, and it is doing this all the time. I know it isn't normal, its one of those things you can just feel. I just am having a helluva time trying to find the source. Anyone else?

 

Up

Also, I went to warm up the car, and listen for any vacum leaks again. It had been sitting for close to 2 hours, so it was well within "cold" parameters, but when I started it the RPM's were at like 600...which is WAY too low for warm-up idle. I blipped the gas and the rpms fell to "normal" warm-up idle. I think this is somehow related, because this started happening after the TPS and IAT sensor replacement. I am in a jam here guys, anybody know ANYTHING about vacum and how I can pinpoint any sort of leak?

 

did you adjust or change the TPS screw(or whatever that screw is called)? Is the idle bouncing up and down, kinda like it you were running big cams? when you start the car up the idle should be higher than normal until it warms up then drops down to around 750rpm.

 

Thats exactly the way it should be, and thats exactly the way it USED to be...until today.

I was reading some other archived posts and it seems if I take off the IAC sensor, and adjust the idle then, the ECU wont compensate for it? Is this true? I may go give it a shot here and post back.

 

Ok. This is what I just did:

-warmed up the car until the fan came on
-popped off the IAC sensor harness
-adjusted the idle to about 750
-turned off the car
-disconnected the negative terminal from the battery
-plugged the IAC sensor harness back in
-watied about 30 seconds
-connected battery
-turned on car

....what did that do....well, it didn't fix my problem.

I went for a 30 minute test drive, and this is basically what is happening:

Upon decel, when I put the car in nuetral (or engage the clutch), the revs fall to about 1600. Once I come to a COMPLETE stop, the revs fall to 'normal' idle.

Another thing that is happening, I mentioned this before, whenever I start the car after it has been cooling down, the car starts normal, but then the revs fall way low, like 600 low. I have to blip the gas to get the revs to return to the normal "warm-up" routine...then it seems to be fine.

I have some questions that I have been thinking about:

1) I am using a civic DX TPS sensor. I figured (and have always thougth) that a TPS sensor is a TPS sensor. Am I wrong? Do they have specific attributes for specific models?

2) I bought the IAT sensor new yesterday, is there a break in period for it to start opperating normal? This may explain the warm-up idle.

I am really looking for answers here...plz help!

 

Ive seen similar problems like this before. When I put ITR cams in my B16 Del Sol, when ever I would come to a stop and put in neutral, or push in the clutch, the idle would bump back and forth a few times before finally settling at the right idle rpm. i just figured it was from the cams. I tried to adjust the throttle screw to increase the idle, but the ECU kept over riding the change and bouncing the rpm back down, so the idle would just bounce from 1500 to 700 repeatedly and eventually settle. I never got it resolve though and no longer have the car.

 

same problem happened to me. fluctuating idle all the time in neutral or when clutch was in engaged. finally i pulled off a vaccum line from the FPR to the intake manifold and it regained a rock constant idle at all times. never figured out why that fixed it and no one else could answer it for me either. good luck

 

was the tps adjusted correctly when installed?

 

Yeah, I always thought these weren't really user serviceable or replaceable, hence the "rivots" holding it in, and that it needed to be calibrated to your specific throttle body.