Base idle on my 94 GSR is a lil bit rough. It sits right at 750, but it feels as though it has a trouble maintaining it sometimes, cuz it wavers a bit. It used to idle rock solid between 750 and 800 RPMs. When an accessory is on (like AC, or headlights) it idles fine.
Its the no load idle that's screwy.
What I have done so far:
I used some TB cleaner. I reset the idle speed using the procedure outlined in the service manual. I have checked for vacuum leaks, checked the ignition.
I even Filled up with different gas.

Any ideas would be super.
TIA.

 

How about injector cleaner? When's the last time you did an overall tune-up? How about fuel pressure (I doubt that's the problem but, hey, you asked for ideas....). Also, is there any correlation between the fan activating and the idle speed? My typically drops 100-200 rpm when the fan comes on occasionally. Sometimes when I'm sitting for a while and the fan is cutting off and on continuously, it seems like an erratic idle.

I don't know. Racking my brain trying to think of stuff. Hope you figure it out.

 

is this the stock TB?

oh, and how much does it actually waver? 100? 1500?

oh(2), and this is both cold and warm engine - same thing, same variance?


[Modified by Go Mifune, 11:57 AM 8/22/2001]

 

Yes, it has the stock TB. Car has AEM CAI, Greddy Header and a Catback. Fresh NGK plugs, cap and rotor. Wires are NGK, about 3 years old but check out fine.
The idle does show a noticable differance when the fan comes on, but this problem is not related to that. I did run a bottle of fuel injector cleaner through the car a couple of weeks ago. The problem occurs after warm up. Cold idle is spot on.
The idle will bob around 700-750 or so.. its not the amount that bothers me, its the fact that it just started doing it. The factory spec is 700 +or- 50 RPM I think. So, according to Honda its A-OK. Something seems off, it seems weak.
Thanks for the suggestions guys.

 

idle rpm goes up when the fans come on - this is not a problem.
the factory spec is 750 plus minus fifty but that doesn't mean it's supposed to fluctuate.
the "fast idle thermo valve" controls and elevates the rpms on a cold engine so that's why it's ok cold.
did this start after the injector cleaner? and is it long gone or still in your (same) tank?
i think a bob of 50 or so rpm might be hard to track down. some long shots are iac (idle air control valve) problem (or beginning of problem) or TB (plate) is no longer sealing perfectly.

now when you say it seems off and weak well...can you describe it? general loss of power?

also, is the bob intermittent or pretty much the whole drive, every drive?

 

Weak, meaning its not a stable feeling idle. Like it used to have, or when there is an accessery on. The car runs great and gets wicked gas milage.
This the injector cleaner tank of gas was gone long ago. The idle does get a lil rough everytime i drive it.
Ill check the throttle plate again.

 

How is your ignition timing?

My car was doing this a little bit when my valves were adjusted too tight and my timing belt tensioner was a little loose. The car was idling rough and every so often it would 'dip' and then rev back up all on its own.

Once I tightened the tensioner and re-did the valves, the problem went away.

Dustin