qat727

The Story:

I've been having a problem with the idle bouncing in my car since I got the thing. 1992 Si, D16Z6.... It was doing it with the original engine, so I figured it would solve itself when I swapped engines. It didn't. Checked every vacuum line and no leaks, but it really didn't act like a vacuum leak. When it's at idle, it's like it goes from a good idle, to wanting to die, to up around 1k, then back again. I got the engine that's in it out of a 1994 Ex that DID NOT have this idle problem. Swapped the complete Z6 and trans out. Changed out the P28, ELD, charcoal canister, and probably a few other parts that don't come to mind at the moment. Searched all around here and found other people with this problem, but no surefire solutions.

Cliffs notes:

surging/dying idle at random times for no good reason
Car did it before motor/trans swap
motor/trans didn't do it in the old car
checked vacuum lines..... no leaks that can be found
changed out ECU.... no noticeable effect
changed out charcoal canister..... fixed the vacuum leak, but not the idle issue.
changed out fusebox/ELD..... no noticeable effect.
O2 sensor/manifold is from previous car.... no known issues while in previous car, but have not been replaced.
Idle is within specs for vehicle when not surging
Engine timed and is within specs
plugs/wires/rotor/cap ~ 1 year old
idle condition exists with different plugs/wires/rotor/cap
idle condition seems to happen slightly more often when vehicle is cold, but is just as likely to occur on a hot engine
issue does not seem to be effected by the manner of driving. I can pull up to a stoplight after I've been pussyfooting it, and it will start bouncing around, or I can drive it like hell and pull into a parking spot and have it do the same.
It does not correspond to any kind of electrical drain. It will occur with no lights, no radio, no interior fan, and no cooling fan, and still happen.
If the vehicle is operated at partial throttle, i.e. at least 1,000 RPM, the issue goes away.

I have tried to be as absolutely detailed as possible. I've tried everything that has been suggested before and I'm at a loss. Can anyone think of anything else to try? This is frustrating me like all get out.

SOHCmaster

Sounds like a vac leak to me, and or sticky IACV

qat727

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PK SPEED &raquo;</TD></TR><TR><TD CLASS="quote">Sounds like a vac leak to me, and or sticky IACV</TD></TR></TABLE>

I'm at a loss for which vacuum line it would be. There is no hissing sounds, I've checked every line under the hood on multiple occasions, and I've sprayed ether around for good measure. I did find that I had a vacuum leak from the canister, but after I fixed that, I haven't found any other leaks.

I was under the impression that the IACV was bolted to the intake. Is this not the case? If it is, it got swapped out of the other car, and was working when it left the car, and was out of the other car and into mine in 3 days time.

Thanks for the suggestions, though. Keep them coming.

Falqon

http://www.ef-honda.com/ben/Badidle.php

My money's on the FITV

qat727

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Falqon &raquo;</TD></TR><TR><TD CLASS="quote">http://www.ef-honda.com/ben/Badidle.php

My money's on the FITV</TD></TR></TABLE>

I can try pulling it off, but the thing that is throwing me more than all is that
A) My car did this before the engine swap
B) The car I pulled the engine out of didn't do this
C) My car does this with the new engine

I had figured that pulling the engine and getting it hooked up in 3 days would be a short enough time that it wouldn't have been broken. Perhaps something did break. I guess I can try pulling it apart.

Falqon

Put your finger over the lower hole in the throttle body after the car warms up, does the problem go away?

Put your finger over the upper hole in the TB does the engine die?

qat727

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Falqon &raquo;</TD></TR><TR><TD CLASS="quote">Put your finger over the lower hole in the throttle body after the car warms up, does the problem go away?</TD></TR></TABLE>

That's one of the problems. There's not rhyme or reason as to when it decides to act up. I can start it, have it warm up, go to work and park it and never have an issue one morning, then the next morning it can be sitting at the stop light and want to sputter. I can't get it to replicate itself for anything. I'd be more than happy to test if I could get a chance to try when it's doing it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Falqon &raquo;</TD></TR><TR><TD CLASS="quote">Put your finger over the upper hole in the TB does the engine die?</TD></TR></TABLE> I can try doing this and the other suggestion once it's warmed up. Perhaps I'll find something on the motor got broke during the swap and is also broken on my last motor... that would be a real way to mess with my head.

civic_driver

check for air bubbles in the coolant system. also, make sure you have clean & tight grounds

qat727

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civic_driver &raquo;</TD></TR><TR><TD CLASS="quote">check for air bubbles in the coolant system. also, make sure you have clean & tight grounds</TD></TR></TABLE>

hmm.... I thought I had bled the coolant system, but I can double check... As for the grounds, they could cause this? Hmm... either way, I picked up some army spec braided tinned ground strap a while back. This gives me an excuse to make the new cables I've been meaning to. Looks like I'm getting a to-do list for the weekend.

civic_driver

bad grounds could cause similar problems.. not getting correct signal from sensor, loose wires moving around as engine buckles, etc. a number of other things with different sensors... it's pretty rare though.. usually the car runs sluggish with bad grounds... i'd check the air and make sure you run the heater in full power while you add coolant if needed..

check FITV, EICV, TPS, MAP, PCV, coolant air bubbles, alternator mechanical problems, O2 sensor, etc.

kkim

have you measured your fuel system pressure? seems you've tried everything but the fuel system.

sicones

did you use the original harness that you had in your car, that my be the problem, a loose connector from your old harness that looses a connection and any random time

qat727

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sicones &raquo;</TD></TR><TR><TD CLASS="quote">did you use the original harness that you had in your car, that my be the problem, a loose connector from your old harness that looses a connection and any random time</TD></TR></TABLE>

I have become inclined believe that there is a VERY good chance that this is the problem. I used the engine harness from the other car, but the rest of the harness hasn't been changed out. I'm having problems with the wiring inside of my car not working properly, so it's possible that this might be an issue. Any clue which wire I ought to look for?

vtakvtrak

I have the same issue, it does it at random, like i would drive to work for a week and not happen then it will happen once at a stop light heh so weird, but when i throw it into neutral and rev it , it goes away

egyolk

iTrader: (1)

i put all my money down on the IACV, i tried everything you tried to fix my hunting idle ie. ecu etc. and finally when i cleaned out that biotch my idle is finally stable in all cold hot temps and start ups goodluck 2 u

vtakvtrak

how did you clean out ur iacv or did u just buy a new one?