Need Help Diagnosing Rough Idle

StoobyMcDooby

New Member
Hey everyone.
1995 Integra SE , bone stock, 245k miles, 5spd, Original drive line. 2nd owner.
The car itself has been great to me, very little maintenance needed with the exception of normal wear/tear stuff. Within the last 10k miles, the car has begun to idle somewhat un-smoothly. Not really rough, just sometimes the revs drop on their own to the low 100 hundreds (when it's warmed up), almost to the point of stalling. Then they usually bounce back and runs at a very normal 800-900 rpm at idle when warm. Does NOT do this all of the time, but regularly.
It has become an everyday thing. If you crank the car up, let it warm up completely on its own, no driving or anything, the idle will kinda float up and down. NOT an idle surge associated with Idle air problems etc, I've had those before.

I continue to do routine maintenance, plugs, wires, cap, rotor, air filter. All of that has been done. I don't cheap out on parts, ignition stuff is NGK, etc.

What am I looking at? Only thing I haven't touched in the ignition system is the distributor and the coil. I have seen the threads regarding advanced ignition diagnosis, but my dad is convinced that it is probably something else. The car runs great, but sometimes at WOT the car will "pop", maybe even miss.

Could the idle problem/WOT popping be:
Fuel pump/filter/strainer?
ECU?


What else?

I don't want to/ can't afford to keep buying random stuff hoping it resolves this.
Any educated helpful insight is appreciated!
 
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JemmieN

not a girl lol
I have the same problem with my 2000 LS 4dr. Friend (who is a professional mechanic) told me that it was the idle air control valve. To check if you need this turn your car on (make sure you aren't moving) and turn your wheel all the way to the left and watch the RPMs, if it drops when you turn the wheel then it's probably the idle air control valve. He also told me they run around for $100.
 


JGvtec

New Member
Like he said^

Rough or fluctuating idle can be a couple things.

Vacuum leak
IACV
FITV

You could just clean your IACV out and then check to see if your FITV is tightened down enough. But not tight just snug.
 

StoobyMcDooby

New Member
as stated in the OP, this is not an issue related to fast idle, or idle air. This is litterally a running rough problem, not so much an idle problem. It's idling low b/c of something else. The car is misfiring at times.

If it were a vaccum leak, I would think that it would idle poorly at all times, which it does not.

keep the advice rolling though. Anything helps
 


mdan9193

Mdan
Same problem I'm having, sometimes after starting the car idles normal then drop to almost stalling then goes back up and idles normally. Only happens sometimes..its weird.
 

klutchDb7

ლ(ಠ益ಠლ)
Could still get dirty. I was having the same issue, had my car maintinenced a few months earlier with those all replaced and sure enough, IACV was dirty
 

thenoxus1

Quick-Spool Racing LLC
Can you like..take a video to show how it surges? IACV and vacum leaks are the culprits..almost always. You've replaces the IACV..have you checked for a vacum leak?
 

Frost94

New Member
Im having a similar problem on my 94 RS. When cranked cold it starts up to idle around 1600 to 1800 rpms, then slowly drops down to 800 to 900 when warmed up. I just recently put in NGK plugs, new plug wires, and a new air filter. So maybe this is the same problem?
 

mjones73

New Member
Im having a similar problem on my 94 RS. When cranked cold it starts up to idle around 1600 to 1800 rpms, then slowly drops down to 800 to 900 when warmed up. I just recently put in NGK plugs, new plug wires, and a new air filter. So maybe this is the same problem?
No that's normal..
 

Frost94

New Member
Thanks answers the question on my other thread. Just trying to get use to having something thats not domestic. I must say its pretty easy, and I dont plan on going back.
 

StoobyMcDooby

New Member
ok, let's not focus on the idle problem. The car runs like doo-doo, and consequently its idle is bad.

So forget the idle problem.

If the vehicle is warmed up all of the way, put the pedal to the floor in neutral, it will pretty much choke itself to death if you don't let off of the pedal. It just bogs down. Changed fuel filter today, didn't help - plugs, wires, cap, rotor, last week. Air filter is new. Timing is spot on.

Ideas?
 

StoobyMcDooby

New Member
I changed the fuel filter last night, was original and very dirty, but replacement did not help. I'm going to a full ignition check today, and make sure everything in the distributor is good.. If that's not it, I will replace the ECU..
 


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