Please note that I am not a mechanic, but have some mechanical abilities.

At the suggestion of a mechanic aquaintance, I took my LS to a repair shop for a diagnostic, given a rough idle. No codes were revealed as a result of the diagnostic. On the mechanic's suggestion, carbon deposits were removed from the intake manifold and the idle was stepped up. This seemed to work for a few days.

However over the course of several days following the engine has apparantly found its way back to the old idle when running hot. By hot, I mean after 15 minute drive and when stopped. At these times I can detect the engine switching from one "mode" to the next. This is when the idle drops and the car starts to tremble slightly [idle occurs at the very first line of odometer]. Other than that, the car generally drives strong.

Both mechanics suggested this is not due to engine wear but something else.

I mentioned the oxygen sensor and idle speed regulator to the repairing mechanic but nothing was checked on these since no corresponding codes were brought up with the diagnostic.


NOTE: CLEANING IAC SCREEN FIXED THIS. ALSO MEANT RESETTING IDLE.
WAS FOOLED INTO THINKING IT COULD BE SOMETHING ELSE BUT IDLE SET TO "CLOGGED" SCEEN WAS SO FAR OFF -- IT WOULDN'T HOLD AN IDLE AFTER CLEANING.

 

I have a 90 Integra LS 1.8. Did you have a mechanic perform the fix or did you? If you did, can you give me some details such as....how you cleaned the screen and reset the idle (or re-learned the computer).

Thanks much!

 

Fix was done by me. IAC valve is located on the backside (toward the driver compartment ) held on by two bolts, upper and lower. Forget about any typically sized torque wrench, there just isn't room. You will need a mm box wrench. Snug the bolts, very careful not to overtighten.

First you want to disconnect the electric connector running from the base of the IAC (believe this is what causes reset) and I myself always remove the battery terminal as a formality to prevent electrical harm.

Anyway, remove the bolts, tilt back the unit and you will see a screen on the left portion sunk in tightly by an o-ring type seal, or so it appears. I made the decision not to remove this screen and leave it in place so the seal could not be altered or damaged. Remove what you can safely scrape down away. Next, I sprayed the screen which was about 50 or 60% clogged by an accumulation of matter with carb cleaner, trying not to "blow" the debris inside the unit, if this is possible, then tilting it in place toward the front end, upside-down to drain and dry. Bolt it back and make the connections.

About the idle reset, my mechanic recommended driving the car for the computer to "relearn" what it must. But what I thought was an incorrect idle was the idle set screw, being so far off to accomodate the clogged screen -- I would plan on resetting the idle screw. Its the only one there.

Also, when you are there, you may want to check the vacuum hoses. moving them around may open existing wear spots. Too the coolant bypass hoses on the frontside of the intake. These are more difficult but worth it to replace all at same time. I drive easier knowing they're done(warning; these can be tough to identify: one local Acura dealer gave me the wrong hose, while Napa ordered one of two right.

While inexpensive, these are molded shape hoses, reinforced. Get the schematic and look for yourself. You don't want to get it mostly apart and find out you have the wrong one. [for this you will need long needle-nose with 90 degree bend and a mini straight needle nose, for the constricted space)

If this doesn't help, post back.

 

driving the car for how long to relearn the computer? which way to turn the screw to turn up/down the idle, simply unplugging it causes reset? what exactly is reset? i was told not to spray carb cleaner directly on it... any thoughts on that? as you can see im having a similar problem, and i think its a combo of my distibutor, and this iacv...

 

Have you cleaned it? Tried restarting the car to help the pc along?
By reset, I meant that the pc will have to refind a proper setting.

Checked all your vacuum hoses for hard-to-see pinholes? Right around male connectors.

"i was told not to spray carb cleaner directly on it... any thoughts on that?"

You bet. I called around to get an opinion on this before and all's I could get is "depends on what you use". No real answer.

So I chose carb cleaner but only with care. One mechanic suggested scraping the IAC screen/filter with a wood device, maybe a toothpick but when you open this up if you haven't already you will see how impractical this is. Put some distance between the device and spray nozzel to prevent blow-through. Wet it up and let it drain back down.

 

UPDATE: 94 integra, bad idle

the idle improved greatly, right after my A/C compressor popped. , i eventually had to cut the belt, cause it was snagging the rest of the works. now the idle is much better. i'm told, that the a/c clutch needed oil, which it didnt get in time. so im in the market for a working compressor for a 94 integra.

 

Thanks a lot YID!!! I really your detailed reply. I have not attempted to clean the screen yet but I'm sure it will help a lot. I will the results.

 

Yeah mines been doing that since I bought it, it doesnt do it all the time, I changed a bunch of stuff on the car and finally bought another complete throttle body off ebay with a good tps and it ran like a new car after I changed the unit over with a working throttle position sensor. I unhooked the battery and removed the backup fuse in the fusebox under the hood to make sure the computer didnt remember who it was (because it was a bastard) and it took about 5 miles of driving for it to actually idle again, it kept dying but after it re-learned the engine it ran great.