Wassup my boy just bought a car and once in a while the idle will go UP, DOWN, UP, DOWN. What do u guys think it could be? By the way its an EG hatch.

 

Well if he won't respond, then I will. I have a 1993 CX with a JDM 1994 B18C. I went to reset my ECU by pulling the 7.5 Back-up fuse.

After going on a drive, the idle now fluctuates from 1000-1200 RPM once I am stopped. I fluctuates for a a second or two, then it drops back down to my normall 800 RPM.

It didn't flucuate before I reset the ECU, why is it doing it now? Could it be that I drove the car really hard after I reset the ECU, and now it thinks I should have a high idle all the time?

 

I experianced something like this after I had my gsr swap in my civic. I asked the guys at the shop where the work was done (Sonic Boom in Metairie LA) and they said it had to do with the motor warming up. I also asked the local honda dealer and they confirmed this info. I am no expert, but this is what I was told.

madwilliam

 

My problem couldn't be related to the motor warming up, because my radiator fan was on when the idle was flucuating. Thanks for the response.

Any other ideas?

 

tell him to stop turning on the AC full power, off, full power, off, full power off....

 

Hmm. . .no A/C. . . (I guess) for attempt at humor.

Any other ideas.

 

Did you try resetting the ECU again and seeing if the problem happened again?

 

No, I didn't have time, the World Series was about to start. Tomorrow I will try reseting it again.

Am I reseting properly?

 

sorry for the late response but its a 92 Dx and it happens when the engine is already warm and when it is on park or neutral.

 

the tps may be bad

 

you can reset the ECU by pulling the negative terminal for about 15 seconds. Pull off the IAC on back of the intake manifold. See if the little screen inside is dirty. Pull out some crap and reset ECU and give it a go! COuld be a few different things. Is it doing it ALL the time, or once in awhile? You have a CEL?

 

my car fluctuates too, but i have a chipped p28... so i dunno. it only does it during warm up.

 

No CEL but it does it often. Where is the IAC on the Intake Manifold? And how does it look? Thanks for the replies btw.

 

IACV is on the back of the manifold, side closest to firewall. Pretty hard to miss. Check out the pic of one in this thread https://honda-tech.com/zerothread?id=310858
That also shows the small screens you can check to clean once it is removed.

 

FITV, Fast Idle Thermo Valve

 

Its probably the fast idle thermo valve, but could also be an air bubble in the coolant. Is the car auto???

 

yes the car is automatic. thanks for the replies

 

anyother suggestions??