Hey guys I have a 92 Prelude 2.3 Automatic for about a month. It had a rough idle when I bought it.
Thinking it just needed a tune up. I put Plugs wires cap and button on it. Still the same problem.
An example would be first thing in the morning,m I start it up and it idles fine in park at about 1000 RPMs.
I put it in gear and it will idle fine at about 750 RPMs. When I say fine, I mean you can barely tell the car
is running its so smooth. I drive it to the store I usually stop at and the idle may drop to 500 rpms in gear and idle
rough as you know what. In park it idles at 750 and idles rough also. The next stop light I stop at it will be back at
750 in drive and idle rough again. When i put it in gear it will be back at a 1000 and be smoother but not as much
as it was earlier. It seems almost completely random. The only thing constant is its randomness. It doesnt always
start out smooth. It could be idleing rough as you know what first thing in the morning and get better at some point and
get worse at another. It idles so rough that the steering wheel shakes the cange in my cup holder, well every thing shakes.
Sometimes at lights When its really bad I will hold the brake and give it a little gas and it will gets better. I tried idleing it
up some and it seems to help only marginly. Any help on ideas that would help me to make it run smooth all tha time would
be a great help. Generally I would like to go cheap parts first unless you really think you might know what the problem is.
I also replaced the timing belt since I bought it ( not because it was broke...I just wanted to know that it was new). That
made no change. Thanks Randy

 

did you inspected the fluid in the torque converter? And also for air inside the coolant system?

 

coincidently, I am also running into this problem. And to add to some of the details, i've notice that when there is an electrical draw (ie: AC, fan, or even window usage) on the engine it affects the idle a bit. I read a post about air in the coolant and how it disrupts the flow in the system, but what's with the torque converter thing? If you checked the transmission fluid level you would have to assume that the converter is filling up with fluid wouldn't you? Mikey

 

*Flush the coolant and bleed VERY good
*Change the transmission fluid
*Change the fuel filter
*check timing
*replace PCV valve
*Inspect and replace any old vaccum lines
*Clean out IACV
*Take FITV apart and make sure the white plastic plunger is screwed in .

These would all be good preventative maintenance

 

Thanks guys I believe I have it fixed. I took and put a new radiator in it. I bleed the system and then started the car and put more antifreeze in it till I seen very few bubbles coning out. I contiued to bleed the system every afternoon for several days in a row. Every time the idle would speed up on its on. Iwould adjust the idle down by adjusting the cable. And every time the idle got smooother and smoother. Its still not perfect, but it is idling a tremendous amount better. Of course i want it even better. I plan to continue on this course for the rest of the week and see how its doing friday. If I think I can get it smoother Ill try some of the other ideas. I do have a question. Is it possible to get it so smooth you might forget that its running already and try to restart it. I dont wont to waste my time trying to get it that way if its not possble.
Thanks Randy