A2brb

Model: 1992 Honda Accord EX (Automatic Tranny)

I searched around on this forum and found some good tips to help with the bouncing Idle.

Specifically Here: https://honda-tech.com/forums/honda-accord-1990-2002-2/1992-accord-lx-idle-air-control-valve-were-1704468/

Here are some things I have cleaned/Checked:

1.)Cleaned the IACV Screen with some carb cleaner.

2.) Replaced the PCV valve.

3.) Opened the cap on the FITV and made sure the little yellow donut was not stuck blocking the Hole.

4.) Checked Coolant Level

5.) Quickly Ran through the Vacuum lines to see if loose or dry rotted. Nothing stood out..Maybe I need to double Check.

6.) The Throttle Body to Block Gasket was changed when I swapped this engine into the car 2 years ago.

I swapped this engine in 2 years ago and had no problems until now. It was a gradual thing. Kind of a rough idle and then gradually go worse and the car wants to take off while breaking at a red light. Drives fine once I'm accelerating and driving down the Highway.

As you watch the video and I draw in closer, you can here a hissing/sucking type of noise. I'm not sure this is normal.




What do you guys think?

GhostAccord

Sounds like a vacuum leak to me.

Have you tried spraying small amounts of carb cleaner at all of the gaskets and vacuum ports? If your idle drops after you spray a spot with carb cleaner you found a leak.

A2brb

I haven't. I'll sniff around some more and see what I can come up with.

duct-tape

i would check the intake manifold gasket i had the same problem.

GlassJAw

Have you tried removing the rubber intake arm and putting your finger over the bottom hole next to the butterfly??
Sounds exactly like the problem I had with the civic last weekend, I only found this to be the problem thanks to what I found on google -

(I skipped down to # 5 and it resolved my problem)

Bad Idle Troubleshooting
This is for high and roaming idles but may work for low idles as well.

First, terms:

TB – Throttle Body
IM - Intake Manifold
IACV – Idle Air Control Valve (also called the Electronic Air Control Valve or EACV)
FITV – Fast Idle Thermo Valve
TPS – Throttle Position Sensor

I finally got the swap (b18a) in my civic. Unfortunately when I started it up it idled at 3k and then had a hunting idle from 2k to 2500 rpm when it warmed up. I stood over that thing for 3 days, testing and scratching my head. On top of that I did a TON of searching on the h-t, hybrid boards, and on here. I hope what is contained within helps someone. Maybe they wont have to go through as much work as I did.

The idle on our Hondas is a tricky thing. It is controlled by two main sensors: the FITV and the IACV. The FITV is a mechanical valve that is controlled by coolant temperature (there is no ECU plug to it). When the coolant is cold the valve is open and letting air into the IM through a hole in the TB before the throttle plate. This essentially creates a small vacuum leak which in turn lets the motor idle higher than normal (supposed to be around 1500-2k for warming up). As the coolant warms up the valve closes and no longer lets air in through the hole in the throttle body. All the while the IACV, which is ECU controlled, is letting small amounts of air into the IM through another hole in the TB. Any amount of extra air the ECU is not expecting will confuse it and you will get either a high idle or a roaming/hunting/fluctuating idle. On to the troubleshooting.

First things first, don’t skip any of these steps. From what I have read (and experienced) usually small dumb things cause these problems so don’t overlook anything. Also refer back up to the pictures if need be.

1) Check your vacuum routing. On the underside of your hood there should be a vacuum diagram. If there isn’t a diagram under there, there is one in a Helms, Chiltons, or Haynes manual for your car (you should have one of these anyway). Remember, ANY extra air will confuse the ECU. Check for cracked or bad vacuum hoses. If in doubt just replace the hose, they are cheap.

The PCV valve could also be the culprit. Take it out and examine it. If it is cracked it could be causing a vacuum leak. Replace the peice if you arent completely sure it is ok (the helms/chiltons/haynes manuals tell you how to check it).

2) Check to see that your throttle plate is closed all the way. Take your intake off at the TB and check to see that nothing is blocking the plate. If nothing is in the way and it isn’t closed all the way, loosen your throttle cable.

3) Check to see if the nuts holding the TB and the IM on are tight, this was the source of my idle problem. If they are loose, tighten them.

4) Bleed your coolant. Some air bubbles may throw the FITV off and keep the valve open.

5) Take the 3 10mm bolts out of the FITV (you don’t have to take off the coolant lines). Then take off the 2 8mm bolts off the plate on the back of the FITV. Once the plate is off you will see a white plastic thing, screw that all the way in. This causes a TON of people’s hunting idle problems (it’s a source of a vacuum leak). Put the FITV back on and start the car up. If it still idles bad go on.

6) Clean the IACV screen(s). See Oz’s write up elsewhere on G2IC.

7) Make sure your car is completely warmed up. With it running, take the intake off the TB. There are 2 holes right in front of the throttle plate, these are the holes that feed the IACV (top hole) and the FITV (bottom hole). With your finger, cover up the bottom hole (it should NOT be sucking if your car is warmed up). If the idle goes down the FITV is to blame, either get a new one or take it apart and screw the valve completely closed (I have only read of people doing this, so I don’t know exactly how. Also, you will have to keep the engine speed up yourself when the car is cold).

Next cover both holes up with your fingers. The car should sputter and die (or almost die). If it does then the source of your crappy idle is the IACV. Replace it. If you want you can test the IACV. Shut the car off and put + battery voltage to the blk/yel terminal (on the valve) and momentarily touch ground to the blu/yel side. When doing this the valve should click, if it doesn’t, replace it.

If, when covering both holes the car still has a high idle, you have a vacuum leak somewhere. Again check the IM and TB nuts. You can spray carb cleaner around those areas and if any gets sucked in (the engine will rev) you have found your leak. Another source of vacuum leaks are where the FITV and IACV connect to the IM. Either replace the gaskets or use silicone gasket sealant.

8) If nothing has worked you should test your TPS. Probe the middle wire on the TPS plug (with the key on but not running, and the plug still connected to the sensor) with the + probe on the volt meter, and the neg probe to ground. You should have .5v with a fully closed throttle plate and 4.8v with it wide open. If the TPS is off, replace it. My TPS was .425v to 4.55v and it idles fine now so I don’t know how big the margin of error is. Also, it is pretty rare for these to go bad.

9) If, still, nothing has worked you might want to try a new ECU. This also is very unlikely, but worth a try.

10) If it still idles bad, go through the steps again.

A2brb

Update:

Sprayed around with Carb Cleaner and got a few Revs in the idle around cylinder 1 at the Intake Flange. Ended up replacing the Intake Manifold Gasket and problem solved.

Thanks for all your input.

GhostAccord

Glad to hear you found the source and fixed it yourself.

aleks77

Having same problem, but im not sure if the holes on the TB are the same on accords as civics?? Cause the FITV is on the bottom of the TB on civics but on the far right on accords.

Anyways, i cover the TOP hole and the car idle PERFECT, what does this mean/how do i fix it? Disconnecting the electric plug on the IACV does nothing, just does it a little less.

spacetech

Not sure if anyone will read this but here goes: I'm having problems with a rough idle when the engine is warmed up and my accord idle a bit low - about 600. I cleaned the IACV and the FITV looks fine. I don't believe I have any vacuum leaks and I'm not too sure what the problem could be. Should I just clean the FITV or is there something else I could do?