Ri5e

I'm frustrated about my idle. I recently put in an STR Intake manifold and everything is positioned like stock. I reused every sensor.

Keep in mind, I have an 96 OBD2 Integra. Do they have the FITV? Or is the idle all controlled by the IAC Valve itself?

During cold start up the engine idles fine at 1,800 RPM then drops a little. Right when the coolant gets warm I guess the IAC 'kicks in' and thats when the problem starts. The idle drops to 800 rpm and jumps up to 1,700 rpm and keeps doing it.

I was wondering why the IAC Valve needs the coolant lines? Is it for keeping it so that it doesn't "freeze" up for people that live in cold areas? Or is it for the ECU to check the temperature to activate the IACV?

I think my funny idle has to do with the IAC. Because I disconnected the plug and the RPM stays at a constant 1,100 RPM and the CEL turns on. I plug it back in and get the same idle fluctuation. I think that high idle without the IACV might be a vacuum leak? But I can't seem to find any.

When I turn off the car and turn it back on it idles at like 1,500 RPM when the car is warm. Then I touch the throttle just a little, 1% and the idle goes up and down between 900 and 1,700 RPM.

From what I've heard, if you disconnect the IAC Valve plug the RPM should hover at around 600 RPM. And if its any higher then that could mean a possible Vacuum leak somewhere.

Could a vacuum leak make my IAC Valve "confused"?

Also I have yet to change the Coolant. I heard that air bubbles could also cause this problem? But wouldn't air bubbles cause it to happen not so often? because mine goes up and down every second...and I dont think air bubbles travel through the cooling system that fast!

When I push on the gas so it goes to 3,000 RPM, I guess its in open loop because the car feels normal. Also when I drive it feels normal. Only during idle this problem happens!

Help me...

sgT

coolant keeps the IAC valve from sticking in cold weather.
Serves no other purpose. I remove the lines from the IAC all the time.

FITV is bolted to the bottom of the TB, so it should be obvious if you dont have one.
I generally remove those.

Are you sure you wired everything properly? The IAC plug is the same as the EVAP
and IAT which can be nearby.

Ri5e

From what I've heard, late model cars don't have the Fast Idle Valve. The IAC controls idle depending on engine load and it also controls idle when the engine is cold. Thats why the IAC has the coolant lines running into it right?

And if those coolant lines are disconnected the ECU will see the engine as "cold" and will make the idle high, right?

B18C-EJ1

BG - Did you replace your T-body gasket when you installed your STR manifold?

If the answer is NO, then this is most likely the reason for the odd idle.

If the answer is YES, did you torque the bolts down properly and in order?

Vacuum leaks can cause the same effects as a bad IAC

tinkerbell

nah - he said that idle is 1100 with IACV disconnected?

if this is true, the culprit may well be the IACV...

only way is to replace with a known good unit.

t..

tinkerbell

no, that is what the ECT sensor on the head is for.

t..

kinesistech

All of the info so far leads to a vaccum leak. Which TB gasket did you use. They arent all the same. If you have the wrong one, you can have a vaccum leak right there. Make sure your using the right gasket and check for vaccum leaks.

The coolant lines have no effect in this situation, just leave them.

Have you tried adjusting the idle air bypass screw? If its too far open the iac may not be able to compensate unless its in a high idle.


[Modified by kinesistech, 12:26 PM 8/15/2002]

88_SC_CRX_Si

Like mentioned above, try re-setting your idle unplugging the IAC, like you have it right now. Then re-set the ECU, after/before plugging it back in again, and try starting...

Ri5e

I'm still trying to troubleshoot the problem. I unbolted the IAC Valve, (But left the plug in) and pulled it away from the manifold. I then pluged up the two holes with my finger. And had someone start up the car. The idle is darn high, like 1,300 RPM. But does not fluctuate!

I then pulled my finger away from the whole (creating a big vacuum leak) and the idle goes up and down, up and down....

I then quickly plug it up again with my finger and the idle is fine but is still pretty high, 1,300 RPM.

NO CEL. Which sounds like there is a vacuum leak somewhere.......

I then screwed the IACV back in and removed the plug. Got a CEL. Idle is still high at 1,300 RPM but the RPM Doesn't fluctuate.

I put the plug back in and the idle goes up and down, which makes me believe that there is some sort of Vacuum leak somewhere!

Anyone else agree?

Spade

I agree.....time to take some water and rub the hoses....

Quik Chris

I don't know about the STR manifold, but when I put my JG Edelbrock Victor X manifold on, it seemed like the potential for a vacuum leak is really high. Did you have to screw in brass fittings for all the vacuum lines? If you did, did you use teflon tape on them? If not, disreguard that. Sounds like a vacuum leak, to me. I've had a bad T-body gasket in the past, but that just made the idle really low when I would come to a stop-- I would have to heal-toe the gas just to keep the car running (how I learned to heal-toe, haha).

Are you sure the IAC valve didn't get dropped when you had it off? I doubt it, but they do go bad all the time... You might see if you can find a used one and see if you use that one, it goes away.

HYBRIDHATCH92

i'm having the same problem i'v been tring to fix it for like a week and a half.......i'm using the skunk 2 IM.....i dont think it a vacuum leek i'v checked everthing........are you getting a cel i'm getting code 41....

Ri5e

I found the problem. The Gasket was too small. The throttle body gasket. The STR's bore is too big and the gasket is too small.

95GS-R

Give this man a prize, he said it first!

BTW: How are you going to fix the problem? Does STR make a bigger gasket?


[Modified by 95GS-R, 12:38 AM 8/24/2002]

Mikey3000

i used a stock honda tb gasket with my str manifold and i don't have any fluctuation. it was obvious that the gasket bore was smaller than the plenum opening though. i was worried about that too but it's ok. did you already change it out and try?

bryan305

When the engine is warm, put your finger over the lower hole in the front of the throttle body. There should be no vacuum from that hole. If there is, then it's the FITV that's giving you trouble.