Is there an adjustment for the fast idle on an '88 CRX? I just started driving the car again after several months (I was converting from auto to manual in my spare time, then the weather was too bad to drive the car), and now I'm noticing that it takes a LONG time for the idle to come down from the cold start/fast idle...

I've changed a lot of things, including the ECU since I drove it last so it could have to do with that, but I never really drove the car in cold weather until now. Before I start trying to find a bad temp sensor, I figured I'd check and see if there's an adjustment that I can use to fix the problem....

Any advice or help?

 

This should help you out. But just fyi, always check the faq section first to avoid flameage.

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/how-fix-your-idleing-woes-fitv-iacv-2153910/

 

Thanks for giving it a try anyway... That article seems to address erratic idle for MPFI cars though. Not exactly my problem...It did give me one idea at least. Since I had drained my radiator to replace the drain plug at the same time I did the trans swap, maybe I have some trapped air in my cooling system (It's been over a week since I started driving the car again. I figured it would have worked its way out by now). What's the best way to bleed the system?

 

It takes a bit longer. What are we talking, two/five min worth of cold idle?

 

8 miles worth of highway driving, then about 1/2 mile of stop and go this morning and it still wasn't down to 800. I'd say it was about 35 when I got to work. Call it 12 minutes or so. That should be plenty of warmup time.

My Ranger is off fast idle by the time I've gone three blocks in similar weather.

 

A little more info.

I was fiddling at a traffic light on the way home and I noticed two things. 1) whatever the idle is at, it will drift down to that point more slowly than if the throttle was just snapped closed. and 2) For some reason, the idle will jump by about 25-50 rpm if I have my foot on the brake (at a stop light) and then take it off.

When I got home I popped the hood and tried manually blipping the throttle a few times to see if I could see/hear anything. There's a small green plastic fitting/plug on the front side of the DPFI throttle body and it seems as if when I crack the throttle just a tiny bit, there's a buzzing/snapping noise that comes out of this location. I've no idea if it's supposed to be that way or not....

I think the idle jumping is just a response of the changing load on the alternator when the brake lights go on or off, and not part of the issue. But I figured I'd mention it anyway.

 

your brake booster is functioning correctly (idle jump when pressing the brake).
the green thing is your IACV, and that is normal.

Check for a vacuum leak.

 

I looked pretty carefully last night and couldn't find any disconnected vacuum lines. Everything is still nice and pliable, so a hidden crack isn't likely. Still, I spent about 10 minutes wiggling every vacuum line I could find and couldn't hear any leaks and it didn't affect the idle at all. (after driving home and idling in my driveway for 10 min, the engine was still at 1000 rpm).

I'm beginning to think that either my 4 month old thermostat has stuck open or I have a bad temp sensor. Does anybody know if it's the water temp sensor that runs the dash gauge is also responsible for telling the engine when to use the cold start enrichment circuit?

 

no, it is not.

spray around the intake manifold area with carb cleaner, the engine will bog down if there is a vacuum leak.

 

Haven't used that trick for years. I don't expect a vacuum leak to be the issue, but it's worth a try. I'll have to pick up some carb cleaner on the way home tonight.

So if the water temp gauge doesn't interact with the fuel injection, how does the ecu know the engine temp? Or does it not use engine temp at all? If not, what controls the warmup circuit on DPFI cars?

One other possibility When the throttle is closed, there's a tiny bit of slack in the throttle cable. Since I changed the pedal assembly, this might be new. Is the throttle cable supposed to help pull the throttle closed? Maybe it's just staying slightly cracked?