89 Accord Idle Problem PLEASE HELP

[twstice]

First of all, i want to apologize for posting this same thing again, but i have gone through every idle problem i saw on this whole Accord/TSX forum, and i see none that match my problem exactly. Below is what i posted in a previous thread, but didnt get a reply, so i have done some tests and have some updated info that might help narrow down the problem.

"I have a 1989 Honda Accord SE-I 2.0 four cylinder fuel injected w/ auto transmission. it has 190k miles on it and runs fine until recently. I got in the car yesterday morning, start it, and it revs up to about 2,000 rpms(normal warm-up) but then it raises slowly up to 3,000 rpms and sits there. I finally put the car in gear and leave. It seems to be driving fine till i get a little ways down the road and let off the gas, it feels like the accelerator is stuck and its goin by itself, so i put the car in neutral and roll to a stop. It is idling ver erratic : from a normal idle, it revs way up 2,000 rpm and then stops and goes right back down to idle, then back up again, then down, etc. And it just keeps doing that. Any ideas on what would cause this? Thanks."

After reading all the threads that looked related to my problem, i narrowed it down to the Fast Idle Valve or the Throttle Position Sensor. I was almost positive it was the Fast Idle Valve because of the following symptoms : Starting at cold it would rev up to 2,000 rpm like normal but slowly climb up to at least 2,500. If i push the gas pedal it will rev up and drop down to 1,500 rpms and then the up and down starts from 1,500 to 2,100 rpms non stop. I took the fast idle valve off, cleaned it thoroughly, put it back on, started the car, and it was exactly the same. After just now reading another thread on here it said that if u take the cap off of the fast idle valve, start the car, put ur finger over the hole in the valve, then it should idle back to normal. I did this and it still idled exactly the same. I also took a screw driver and pushed the valve down while it was running, it revved way up higher, but still did the up and down at the same time....so i guess it can't be that?!?! So now, im guessing it is the TPS. If it is the TPS i noticed that it is rivitted (sp?) onto the throttle, which sucks *slaps Honda* would my best bet be to buy a whole throttle assembly at a junkyard (not sure what that would cost) and stick it on mine? or if anyone thinks it may be the Fast Idle Valve for sure, i can get one of those at a junkyard for 15 bucks. Anyone have any comments/suggestions/solutions/tests, please feal free to post, i really need to get this fixed.

[jeffcoslacker]

A tps shouldn't do that. I'd be more suspicious of the IAC (idle air control), if it is so equipped (not familiar with all Honda's terms for things). The IAC controls the amount of air allowed to bypass the closed throttle plate at idle. On cold startup, when a rich mix is required, it should be almost completely closed. As the engine warms it will open and allow for a leaner mix.

If it gets dirty, it will get stuck in spots, and change positions in a "notchy" manner instead of making smooth transitions. If the valve gets stuck in a position that admits more air than is required, the PCM will command additional fuel to compensate, and the idle will jump up.

Check and see if there is such a component on your car. It sure sounds typical of an IAC malfunction. They can be removed and cleaned so they work right usually. Clean out the air passage also if you do it.

[twstice]

I downloaded a 86-89 shop manual, and it looks like it does have an IAC. But im not positive. It is listed as Idle Control Solenoid Valve. The description sounds the same as an IAC valve. Do u know if it is by any chance? I will check it out tomorrow after school and see if i have any luck with it. Thanks.

[twstice]

I just remembered that when i called autozone they couldnt find a listing for a "Fast Idle Valve" but only for an "Idle Air Control Valve". The fast idle valve actually sounds more like a premature version of an IAC, maybe that is what it is after all? either that fast idle valve or the idle control valve solenoid?

[twstice]

i just got done testing some stuff, here is what i did : Checked all vacuum lines with carb cleaner - I found no vacuum leaks ; Disconnected the Throttle Angle Sensor while the car was running - The check engine light came on but The idle didn't change at all, still up down up down up down, so im curious about that ; I also checked the Fast Idle Valve for the heck of it - Seems to be in perfect working condition. ; Disconnected the EGR valve at the electrical plug while it was running and nothing changed at all, also disconnected the vacuum line running to the EGR while the engine was running and nothing changed. ; I looked for the Idle Control Solenoid valve, and oddly i didnt find it o.O ; Im so lost now