Engine at idle is bouncing between 1000 and 1500 RPMS
 

Hello, I have an 88 CRX with the D16Z6 engine and Vtec Heads. When I first start the car it is revving at 2000 RPM, then after it warms up it slowly works its way down to about 1000RPMs, it will constantly bounce though from 1000 to 1500 rpms rythimatically about the pace of a person breathing. I had thought it might be the O2 sensor (still has the 1 wire one) so I installed it. It didn't help. Not completely sure the O2 sensor wire is even still connected. What else could cause the engine to continually "seek".

thanks for any info

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

A leak in a hose.

Unplug your battery for about 5 mins. PLug it back up, let the car run for about 10-15 mins see if that'll help.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

I'll try that tonight! thanks

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Clean your fitv and iacv. If has not been done yet do it! Also what ecu are you running? If it's a p28 then your gonna want to run a 4wire 02sensor anyways. Lmk

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

O2 sensor will not make idle bounce.. I'd clean your iacv and make sure there's no air in the coolant system. Make sure there's no vacuum leak. Also is your check engine light on? If so you're throwing a code (Check you ecu and if its blinking count the blinks and how ever many blinks is what code you have). Is it boggy When you drive? My a6's engine light was on, threw code nine, had a bouncing idle and bogged.. replanced a brand new dizzy on it then everything was fine..

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

That won't do anything...

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

You need to adjust the Fast Idle Thermo Valve (its on the bottom of the throttle body). unscrew the cover on the back side of it and turn the pluger looking thing clockwise until it stops. Put the cover back on and you'll be good.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Thanks CRXguy, I am still not convinced that my check engine light is wired correctly. I looked for a leak in a hose last night and did not find one.. I did notice that the air being pulled into the air cleaner is pretty loud, the guy I bought it from said it was new, but going to clean it this weekend, as well as the iacv, fitv. I appreciate your guys suggestions. I will let you know once I have that done if it fixes the issue.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Clean and adjust the FITV, clean the IACV. If that doesn't fix it then check the throttle body gasket as well as all the vacuum lines.

O2 sensor won't cause this, and unplugging the battery/resetting the ECU won't make it go away.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

And HAMOTORSPORTS, I'll do that after it is all cleaned

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

iacv go bad on those ALL the time... and thats usually the entire cause

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Actually the one wire 02sensor will **** up your idle etc run rich etc.. Have a 91si hatch stock with same issue but mine was throwing a cel for it, replaced it and made a huge difference.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

cel WILL be thrown for o2

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

SORRY TO BRING THIS OFF-TOPIC BUT I HAVE A QUESTION TOO!!
I bought my crx a few months ago, and i have a b16 with the p28 ecu. I believe the kid put a 1 wire o2 sensor. Which engine will i pull off the 4-wire o2 sensor at the junkyard?

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

D16z6 would work fine. But the ecu that your using is probably chipped and you probably don't have to use a 4wire. If it's the obd0 b16a 88-91. Then just keep the 1 wire 02

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

It's obd1

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

thiss is a def starting place to look^^^

its letting too much air thru thus causing a leak type of idle issue

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

you have too much air going into the intake than the IACV can handle, so it goes into an open loop, it cant compensate. the problem is NOT the IACV itself.

you need to find the vacuum leaks, typically the hoses.

the first thing tho you need to do is adjust your idle screw at TB. turn it all the way in til it almost bogs, then back it out.

whenever this problem happens to my car, this is all i ever do and it always works.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Had same problem did alot research and cleaned and changed iacv my car has no fitv valve and din't help. So on my intake the TPS was not ADJ and the rivits are a bitch to get off without breaking the TPS so i has a SI Throtle body with the rivits already out and the TPS was adj and there was a lil vac leak on the old throtle body, So then by adj the TPS and the dizzy it runs freat like new. Try unpluging the TPS and the IACV and see what happens there is a lil hole in the throtle body when you unplug your iacv put your finger on that port and should idle good..give it a shot and let me know

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

I am having this problem as well. Mine is bouncing between 1250 and 1500 at idle. I checked the coolant, and there was air in it -- but I ran the little release valve until it was all out and topped her back off, so that was'nt the problem. The IACV appears clean enough.

My set up is a D16y8 in a '91 ef hatch with a p28 ecu (running an OBDI to OBDII jumper harness). My y8 is out of a '97 Del Sol -- which ran an ODBII p28 (run searches here on Hondatech for yourself if you don't believe me) . . . so I don't think it has anything to do with my ecu not jiving with my motor.

What else could be causing this kind of bouncing?

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Valentines has been busy so haven't had time to do much.. sometime in the next day or so, I will try a couple of things listed here.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

coo let us kniw what happens

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Im havin the same issues, but I have a 90 CRX w B17. I tried what Tyson said, but nothing, i unhooked the the vaccum hose from the IACV and the idle went down, but my check engine light came on and it started to bog down i really have no clue on what to look at next. really irritates me when im at a stop light. how the hell am i suppose to find out if my car has the FITV?

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

use a water spray bottle and mist around the engine while idling. when you hear the idle change, youve found the location of the leak.

Re: Engine at idle is bouncing between 1000 and 1500 RPMS
 

Are you serious? Can you explain how that works?