rough idle problem - need help

[beetlejuice69]

i recently bought a 92 honda accord LX wagon with an f22a1 2.2L engine with 143000 miles on it...only paid $1000. It is in pretty good shape. it just passed MD inspection. when i start the car it starts up just fine, but after settling down, the engine idles rough. to the point the steering wheel has a vibration on it. not a jarring vibration, but still annoying. it only does this at idle, when in park or stopped at a light. once i am on the accelerator the vibration goes away and the car runs quiet and smooth. i am also getting about 20 mpg city with it. would also like to improve the mileage a bit if possible without a shoebox full of 50's spent. i am obviously not into racing this thing since it is a wagon, but i want to get good mileage and longevity out of this car. any suggestions about the rough idling problem? motor mount bad? if so how do i inspect that for damage? is it obvious and visible usually? timing problem? tranmission problem? my mechanic said nothing to worry about, but i need second opinion.
and any suggestions on increasing mileage and longevity, besides normal routine maintenance like oil changes and filter replacements and that sort of thing?

any assistance is much appreciated.

just fyi - i did do a search in here for similar problems and could not find a match. it does stay at 700rpm when it idles rough. it does not jump around like i read in other threads about idle problems.

i did buy a haynes manual the first day i bought the car, but that thing is so vague since it covers different engines and different configurations. nothing in the troubleshooting section on this sort of idle issue. going to get a helms book now, hope that may be better.

[hondachic]

I wish I knew!!!
I have a 97 with 100,000 on it, and mine started that rough idle at about 80,000. I was told it was the rear motor mount. I spent the $300 for the mount and put it on myself to save the $400 labor. But, the mount DID NOT fix the idle problem. Mine is doing exactly like yours. Only in park or at a stop light. Sometimes though, it's like it snaps out of it and will not vibrate and I have to turn my radio down just to be sure it is still running. LOL I have, in addition to the mount, changed the fuel filter, cleaned the EGR ports, had the injectors cleaned, valves adjusted. which greatly improved fuel mileage, new plugs, wires, cap and rotor. And other minor things I thought would help to no avail. But my theory at this point is simply this. Whatever is causing it has to eventually break completely and then it can only be one thing!!! But, if anyone knows the real reason, I would also like to know!!

[Nildey]

I think it has to do with air flow to the engine. It's a mass air flow sensor in newer cars.

[beetlejuice69]

well i just spent another $900 on a new timing belt, water pump, seals, head cover gasket, new front flex exhaust pipe (all which needed to be done anyway) but it did not improve the vibration. and again the mechanic said it is normal with high mileage hondas. the car feels much better now with the new belts and everything tight again, but can not figure out the dang vibration. next on the list in a new front (dogbone) motor mount which looks like it is showing its age, and may invest in some new sensors (O2, iac, map), EGR valve, and get the injectors cleaned and adjusted. even if that doesnt solve the problem, i will have more piece of mind driving this older mileage car that was not maintained as well as should be expected. but hopefully if i can get it finely tuned as much as i can without a huge overhaul or rebuild the problem will disappear...that or i will have gotten used to it by then. thanks for the responses though.

[CBFryman]

Could be excesive cam wear over time...But then agian i havent tuned many hondas and im no profectional honda mechanic...has the engin been rebuilt? if it hasnt i would have it rebuilt somewhere between 180,000 and 200,000 miles to keep it purring well...homda makes great motors...as long as the modifications are kept to a minimum...you cant do to a D, B, H, or F series engin what you could do to something like an SR20det and expect them to have the same longevity of the block...but just for kicks...any performance mods at all?