My 94 Accord EX starts normally, initially idles around 1600 RPM, and then it gradually settles down to 700 RPM. I think this is supposed to be normal.

However, after the car has been parked and running for about 10 minutes and warmed up, if I increase to 2000 RPM and then take my foot off the accelerator, it will stay at 2000 RPM and not gradually work it's way down to the normal 700 RPM idle.

I have cleaned the IACV and FITV, but this problem still persists.

Gary

94 Accord EX Sedan, 4 cyl 16v VTEC 2.2L Engine, 4 Spd Automatic.

 

I may have solved this. After resetting my ECU, the idle responds properly.

Not sure why previous attempts at resetting the ECU were not successful. I usually reset the ECU using the negative battery terminal method. I've noticed that sometimes when I reconnect the negative battery terminal I will hear a single click sound from somewhere in the engine. On recent previous attempts I have not heard that sound. I read somewhere that pushing the brake pedal would help clear the ECU. So this time I pushed the brake pedal down once before I reconnected the negative battery terminal, and when I reconnected the negative battery terminal I heard the click sound, and after starting things up and letting it idle for 10 minutes, everything works great. Not sure if the brake pedal had anything to do with that or not.

If the problem comes back then I might be suspicious of some kind of "short term ECU memory loss" problem. Can that happen or do they just fail?

Gary

 

I think the brake pedal is just one way to dissipate any charge in the ECU so it REALLY goes dead. Switching on any lights might do the same thing.

 

My problem has returned. After the car warmed up today I pushed on the accelerator until it hit 2000 RPM's. After releasing the accelerator, the needle just stays at 2000. On previous days since I reset the ECU the needle would drop immediately to 700 RPM's as it should, but not today. The only thing that is different is the weather. Today is around 90 degrees and the other days were around 70.

 

Maybe you have a sticking throttle plate?

I would remove the intake duct from the throttle body and clean the inside of the throttle body with TB cleaner and clean both sides of the throttle plate.

Reset ECU by pulling the 7.5 amp backup/radio fuse in the engine by fuse box for a minute and see what happens.

 

After cleaning both sides of the throttle plate and resetting the ECU the problem reappeared, so I figured I'd take the car out on the highway and "blow the snot" out of it just to see if that would make a difference. The car ran great, but when I stopped and let it idle, the RPM's kept oscillating between 1100 and 1500. So I pushed the accelerator up to 2200, and when I took my foot off the gas it just stayed there at 2200.

The temperature gauge needle rises up 1/4 from the bottom when warmed up. The radiator and reservoir are both full. When I cleaned and adjusted the FITV I did disconnect the small hose, but there was no loss of coolant. I don't think there is any air in the coolant. Is there a likely tempearture sensor that could be the problem? Or is this just the ECU's way of "learning"?

 

When you disconnected the small hose there was not loss of coolant? You mean the line wasn't filled with coolant? If so, maybe the problem is the FITV isn't getting warmed up like it needs to.

Look for disconnected or plugged hoses anywhere at the throttlebody or intake manifold. Some people do that thinking they're improving performance by NOT heating the intake air. In reality the TB & IM make such poor heat exchangers that it really doesn't provide much heating to the air.

 

I would suggest making sure the IACV is not the problem by placing a piece of masking tape over the IACV bypass entrance in the throttle bore. This would prevent idle air bypass and should result in low idle speed. If idle speed stays high, there is another source of idle air somewhere to be detected.

If you find the IACV is the problem, it means IACV is somehow sticking in open position; defective movement or gummy deposits.

good luck

 

Everyone talks about cleaning the IACV & FITV. But there's gotta be some possibility they're broken beyond just being dirty.

Unplug the wire from the IACV & see what happens. This *should* drop it down to the "base" idle of about 550rpm. When you do this, there shouldn't be any suction from the IACV port in the throttlebody. Basically, you're checking to see if the IACV correctly closes when it's unplugged.

You could also go through the process of setting the base idle, resetting your ECU, & forcing it to re-learn the idle.

 

When I cleaned the FITV there was some coolant in the hose that I disconnected, but I don't think there was much loss of coolant or introduction of air into the system as a result of temporarily disconnecting.

I will try the two suggestions for testing the function of the IACV and report back.

I will also look for clogged or plugged hoses.

Another observation:

1) The "initial warmup" always works great and settles down to 700 RPM's. After warming up a little longer it exhibits the "stuck or erratic" idle at 2000. When this happened today I turned off the engine, removed the intake air duct, and started the engine. To my surprise, the idle settled immediately at 700 instead of 2000. When I stuck my finger over the port in the throttle body that goes to the FITV there was a definite suction.

2) Turned off the engine, reinstalled the intake air duct, restarted the engine, and the idle initially settled down at 700 RPM's. But later the 2000 RPM stuck idle returned.

Makes me wonder if I jostled some kind of loose wire or something when I removed the intake air duct.