I have researched this for several weeks and still cannot figure out the issue. Looking for any clues now.
Similar problem description as: http://forums.g2ic.com/showthread.php?217028-another-awesome-high-idle-thread!!-Read-me!&highlight=high+idle
Car: 1991 Integra GS.
History: Car sat in a barn for 5 years. Recently rebuilt the engine, swapped to a manual transmission, manual steering, and ABS removed (ABS computer still connected). Also blocked off the egr valve (still using the auto intake manifold), removed the egr control box, and blocked off the egr vacuum lines.
Car starts up fine and immediately revs up to about 2000 rpms, where it will normally stay. If I let the car warm up completely, shut it off and then start it right back up, the idle goes to around 1200, then slowly climbs back up to 1500 - 2000.
- I can’t find any vacuum leaks and the car almost immediately dies when blocking the throttle body with my hand.
- Unplugging the IACV results in the car returning to a seemingly normal idle speed of around 700~
- Idle screw is completely closed.
- No CEL (except when disconnecting the IACV).
- Tried a 1990 (A01) ECU - Got a code 13, but no change in the idle issues.
- Bled the coolant lines and I have driven the car for over 50 miles.
- Replaced the ECT twice (aftermarket, then OEM to be sure)
- Checked the ECT wire for voltage (4.9v) and ground
- Cleaned the IACV. Twice. And replaced seals.
- Plugging just the IACV port in the throttle body drops the idle speed down considerably, but I can’t tell the exact speed. (no assistant available).
- Cleaned FITV and adjusted. If I plug the FITV port with my finger, the idle speed does not change.
- Throttle plate seems to be in the factory position. Checking the TPS voltage shows about 4.8v with the plate in its “closed” state.
- All new vacuum hoses.
- Replaced throttle body gasket (twice, just to be sure).
I’m stumped. Unplugging the IACV seems to fix the idle speed, so to me the issue seems like it couldn’t be the IACV itself. I don’t really want to shell out $200 for another IACV if its not going to fix it.
the only possibilities i see are either timing, the iacv itself, or something to do with the manual swap.
are you running the auto ecm right now? your valve timing spot on?
you can get a used iacv from the wreckers if you don’t know anyone else with one youcan borrow
I’ll search for a used IACV around here, but used parts can be hard to come by in middle Tennessee for some reason :).
I am currently using the Auto ECU. I’ll recheck the timing again, and also the ignition timing (if that could be related).
Edit: Rechecked the valve timing. It’s spot on.
hmm. yea, you know when you start messing with the original components, they all become variables. tbh, i don’t know on that ecm. i remember back when i had my crx, there was i think one spot that needed tobe soldered to make an auto ecm work for manual. but i think it was to do with the neutral safety. the fact that you disconnect the iacv with the idle screw set all the way in and it still sits at 750 is odd. and the fitv blocked makes no difference. and that no vac leaks are present. it’s gotta be the iacv. the idle screw has the throttle plate closed completely? if so, there’s no other explanation. or maybe you have some vac line(s) routed wrong. when i convert things, i like to convert exactly as it would be from factory to avoid the possibilities
Ok so sounds like it’s the valve under the throttle forgot what it’s called. You need to take it out completely and disassemble it step by step until your left with the brass pin/ valve.
Take pics of it after each part you take off.
Oh and i have the same yr, model, engine and manifold.
You need to get some fuel, brake cleaner to really get all the gunk out l. And you need to get some in the spring pin area to, make sure it moves freely. Put everything back how it was, I closed my valve all the way till it stop then did half a turn back. Bolt it, hook up the coolant lines and start the car. Mine idled at 800 on cold start after that.
It took me like 3 times to do it right or clean it right.
First time I didn’t even take it apart I just sprayed the heck out of it, didn’t work.
2nd time I did take it apart but used grease on the spring pin, wrong. Needs to stay cleaned.
I think team integra forums has I link with pic’s how to do it.
The FITV? I’ll give that a try, but blocking the port inside the throttle body didn’t affect the idle speed.
I have an IACV on order. Should have it tomorrow. Despite the price, I hope it works.
if you blocked the port and it made no difference, it’s not the fitv
Brand new Denso IACV. Still idling too high…
So, I rechecked the ECT plug (while unplugged from the sensor and ignition switch on), and I noticed I am getting 4.8v Red to Ground (battery -), but if I connect to the Green wire and battery -, I am getting 0.03v. Red to Green I show 4.6v. Does this sound normal? It it possible that I am getting a voltage leak, causing a bad reading?
The shop manual just asks if the Red/White wire is approx 5.0v.
Other thoughts… The Power Steering Switch is removed, along with the power steering. The AC Compressor has been removed (forgot to mention that). I can’t imaging that having either of these two disconnected would increase the idle speed.
This is a brand new (rebuilt) Denso alternator. Seems to have no issues keeping the battery charged.
check the TPS that could cause the rev too
what happens when you disconnect the iacv now? what does idle sit at?
Edit: TPS reads 0.49v closed - 4.48v WOT.
With IACV disconnected the idle goes to about 1,000 - 1,250 as well.
Forgot to mention the Idle bypass screw on the top of the TB is completely closed, but I guess blocking the IACV port inside the TB should have ruled that out anyway.
Something else I have noticed. With the IACV connector disconnected, the idle will sometimes bounce up an down 100 rpms. In other words, sometimes it will quickly bounce between 1,100 and 1,200 rpms. This especially happens if I rev it to 2,000 rpms.
the brass screw is actually not supposed to be messed with. it’s set from the factory then blocked. k try this, engine at operating temp, block the iac port. the engine should stall
It does not. Blocking both the iacv and fitv ports only brings it down to about 1,100 rpms.
Still stalls right away when blocking the TB completely.
I know its not to be messed with, but I went ahead and altered the throttle plate screw. Now I can get it to idle around 750, but I can hear some misfires and the idle is a little “bouncy”. The TPS has not been re calibrated, so its at .40v I think.
I’m going to recheck the valve clearances today and set the ignition timing (seems a bit late).
if your timings too far advanced, itll idle high
your throttle plate must be open then. there’s no other place for air to enter with the iac and fit blocked
That is the conclusion I am coming too as well. I made sure the throttle cable and dashpot were not interfering with it.
I cleaned the crap out of it before putting this car back together. I wonder if some of that sludge was keeping the idle speed down.
I just replaced the Distributor. Old one was getting corroded, and someone had been messing about inside (stripped screws and a cracked coil casing). Made small changes to the misfires, but not much.
Back to the throttle issue. Should the stop screw allow the plate to close completely? I thought for some reason the plate needed to be open slightly, but obviously its open too much.
I want to adjust the TPS back to .48v, but not sure where the throttle plate should rest first.
I think my issues are about 98% solved.
I finally just took the TB back off the manifold, cut slots in the TPS and adjusted the plate all the way closed, then opened just enough so it would not “touch” (stick) the inside of the TB. I then set the TPS to .49v, warmed the car, reset the idle screw, and let the car re-learn the idle.
Now it runs pretty smooth and idles around 700-800 rpms. Still fluctuates just a little (100 rpms). Couldn’t tell that it was running lean until I made the adjustments in the TB and TPS, now it seems to be the correct mixture (or pretty close). I need to test the injectors and make sure they are firing correctly as well.
Thanks for the replies!
when you adjusted the idle, you followed the procedure, yes? iac disconnected?
glad its sorted