chillerice

Hey guys, I got a 98 civic ex coupe auto. Aem intake and new headers. My problem here is that I start my car and the rpm goes to like 1.5 or 2k then after a minute or so drops to like 200-400 then jumps back up. Sound like it's gonna stall and the whole car shakes but it idles rough until the temperature gauge evens out.

I clean the throttle body anf the iacv, change my oil and the filter and nothing changed. This is from a cold egine start. Putting it in gear is the same thing only that it's around the 200 mark.

I remember pull the plug off the iacv then plugged it back and the idle went up but got Check engine light. Also when I turn my a/c on the idle drops and the compressor makes this fast ticking sound and the cae feels like it's about to stall.

Do I need a new IACV and a new compressor? I've put alot in this car getting it ready for the road and I'm getting depressed not knowing if it will be driveable.

THC07

did you check for Vacuum leaks yet?

this just happen? has it progressed or has it been the same since it started. if it has an OEM fuel filter, replace it.

Fix the idle first, dont waste time thinking about the A/C yet.

civic 02

it is normal that the rpm drop when you put de a/c on. The A/C takes a little power from your engine to start up

chillerice

I didn't check for vacuum leaks yet,because the idle was good for the whole winter/spring season. I notice that when the rpm drops my lights dim but nothing like my amps or stereo shutting off. I do notice sometime though that there's a quick flash of my bettery light when the rpm drops to 0 and bounce back up. It's a new battery. I'll check for vacuum leaks today and get back to you guys.

fragmare

Double check your mechanical timing

If you've disturbed the distributor in any way recently, check and/or reset your ignition timing.

Bleed your coolant. Air in your coolant can make your idle act wonky sometimes.

Start the car and before the engine gets hot, take some carb cleaner or starting fluid and spray a little bit around the various vacuum hose connections and near the injectors. Listen carefully for a change in idle each place you spray. If the idle changes due to you spraying that area, there's a vacuum leak there.

Try disassembling and cleaning the FITV too.

Take a close look at the rubber seal on the IACV around where the electrical connector attaches to the side of it. If it's cracked, smear some Hondabond or grey RTV all the way around it with your finger to seal it up.

Your A/C compressor is likely just fine. It's kicking on/off because of your idle dropping below 500. That's normal. Your idle dropping RPMs when the A/C is turned on, however, is not normal. Your car's ECU should automatically adjust the idle up by about 100 RPM or so when the A/C is on.

Charlie end all

Mine does that when the water level goes down. It's like the automatic choke doesn't know if it wants to go off or stay on

THC07

thats because your FITV is open. your white cap needs to be screwed back down.

chillerice

I have read that 98 civics don't have a FITV. Not 100% sure though. I did check for vacuum leaks. I even closed off the throttle body and the car dies. What I do notice now is if I close off the iacv hole in the TB the idle get normal but a little shaking is still present.

Also this occurs now. When I have the car warm and unplug the iacv the idle goes up to 1.5 k (normally it should drop ) I even reset the idle screw to 2.5 turns from all the way in and plug the IACV back in and it stays at 1000 rpm for a while then drops to 500. After which when I rev the car the low crap starts but isn't for long.

I think the a/c is working ok right now hasn't been chipping in and out fast only that it's not cold enough. I've put r134a in it and that's when the fast click started but it's gone for now.


I think I'm gonna just get a new IACV (I feel the sensor is bad) & see what happens from there.

fragmare

I think my IACV might need replaced too. I've tried just about everything and the only thing in the shop manual that covers all the things that are wrong with my idle is a bad IACV. Sadly, they're not cheap. I think they start at around $130, even on rockauto. :/

I'm hesitant to get a part like that at the junkyard too, in the fear that I'd inherit whatever idle problems the owner of the junker car had.