Someone's gotta help me out here... this is getting difficult to drive with... (sorry if this is an essay, it's a really, really weird problem)

OK, problem's like this. My idle's usually been pretty good. But lately it's been the *****. It'll seem to idle fine when it's warming up, but when it starts to get into the 'warm' zone the idle drops drastically, down to about 250-400 rpm, then suddenly goes back up. It'll idle reasonably well while driving from then until when it's fully warm.

When it's fully warm, when taking it out of gear the idle will drop down to 750 and then past, sometimes low enough to stall the car. Usually it recovers, the idle bounces around 750 +/- 250 for a few seconds, and then it idles fine. Sometimes, when sitting at a light or a stop sign, the idle will suddenly drop from 750 down to about 250-500 rpm and then go back up. Sometimes it'll go up to about 1000-1100 and then sit there.

The most annoying part is every time I take it up past about 4000rpm, it stalls when I take it out of gear unless I let it coast for about 10-20 seconds. Today it stalled going around a corner; I was pressing the gas and the car was in gear, revving, all the power was on, and the engine just wasn't doing anything. No vroom vroom I actually had to pull over, take the keys out, put on the hazards, start it again, and then drive off. One of these days I'm gonna get stranded unless I fix this

Anyone have ANY ideas? I know it's not a coolant problem... I've just gone through and done the whole cooling system, checking for leaks, replaced the coolant temp sender, and changed to Honda-brand coolant.

 

My '90 Civic Si would drop idle when I'd depress the clutch to coast to a red light or stop. This would happen most when the temp needle would just start to rise. Cold was OK, and normal operating temp wasn't as bad. In my case, adjusting the base idle and changing out the lazy O2 sensor solved the problem.

 

Do you think I could test the O2s by unplugging them & getting it to throw an O2 code?

 

Perfectionist, mine does the exact thing as your car when i depress the clutch to coast to a red light or stop. but i haven't adjusted my idling yet and i can not test my o2 sensor since our SiR here doesn't not come with any o2 sensor so i'm still looking for answer.

 

I unplugged the O2s so it threw an O2 sensor code, and it was fine when I first drove it, but on my way back from work the idle was all over again & almost stalled two or three times... so it's not the O2s

I hate OBD0.

 

did you check your timing ???? this happened to me when my cams were not lined up right

 

I checked it yes, I just changed the timing belt and water pump so it was checked then. I'm going to set the timing back to stock today (it's advanced 2 degrees) and see if that will help.

 

If it is not the O2 sensor check the idle air valve it is located on the back of the intake manifold. Does it do this all the time? Or when the outside temp is warm or cold?
Let me know. Good luck!!!

 

Is that started after you change your timing belt?
I got similar idle problem last month too, after I change my timing belt. Although I'm pretty sure the belts were put on right at the time of install, it turned out that my cam was two teeth off!
Just my two cents.

 

the belt could have skipped teeth afterward. you may not have tightend it properly. also, check for any vaccum leaks, i doubt thats the prob but it wouldnt hurt to look.

 

Well, more updates... just checked my ignition timing w/ the gun, it's running 14 degrees BTDC! I had it advanced two degrees initially, up to 18, and now it's 4 degrees back from that point...?

No one's touched the timing since it started doing this over two months ago. I'm going to pull the valvecover and doublecheck the cam timing in a couple hours, then set the ignition timing to stock.

I'm running 94 octane right now, so maybe the idle's due to a problem w/ not enough advance? The car is surging a bit, and the timing goes to 15 degrees w/ each surge... I'm going to put on silicone vacuum tubing very soon (ie today or tomorrow).

Does anyone know what the fuel pressure should be? It's at 38 psi right now when the engine's off, just from priming the pump, and about 40psi when the car's running.

Lsintegra92, the IACV was replaced w/ a CRX Si unit that should be functioning... it's one of the first things I checked

 

Cam timing is bang-on. I'm going to replace all the vacuum tubing now, then set the ignition timing to stock.

Can anyone tell me what fuel pressure I should be running? It has an AEM CAI and exhaust system, that's about it.


[Modified by raene, 6:38 PM 11/7/2002]

 

I know this might sound weird,but ever since i tosted my clutch,my car has been doing the exact same.its funny how you say it does this while coming to a stop and pulling it out of gear.could the slipige in the bad clutch throw timming off and cause the ecu to act a fool???thats my take on my cars problem.once i have the clutch replaced ill report on the idle thing,like i said my problem started a few days after the the clutch was really hurt.Not only that while driving the rpm needle moves kinda funny while driving, while excellerating and decelerating.

 

Heh, that WOULD be weird, and yet make total sense...

But the clutch is pretty new also (ACT HD)

 

How many miles on the car? Has the fuel filter been changed. Kinda sounds like the fuel pressure regulator to me. IS it stock FPR or modded, I know sometimes if it doesn't let enough fuel flow back to the tank, it can go way rich when you push in the clutch, causing it to idle rough/stall. I would check the FPR according to manual pressure with/without vaccuum attached.

 

I can't check what the fuel pressure should be, it's a JDM 1st gen B16A That's why I'm asking someone to tell me.

I'm using a B&M adjustable FPR, it's been on there since I got the engine, a year and a half ago. The fuel filter was changed about a month ago.

*edit* I just took the car out for a drive after I replaced the vacuum tubing w/ silicone hoses. It still ran like crap, no difference. I stopped at a gas station & unplugged the O2s again and it ran a LOT better. But then near home it started acting up again

I was going to set the timing just now but when I went to start it I didn't hear the fuel pump (Holley 190lph, you can really hear it when it's running). I tried to prime it eight or nine times, but no go...

So it might be the main relay going out intermittently. Could that cause these problems? I'm going to pick up a new one tomorrow


[Modified by raene, 10:32 PM 11/7/2002]