92 Accord - Shakes idling in gear and/or with AC on
 

Anyone know why a 1992 Honda Accord would shake while idling in gear, and shake a lot more when idling in gear or neutral with the A/C on?

Thanks

if its an automatic transmission they all shake when idling. 4cylinder engine, fuel injectors normal, bad motor mounts. egr ports clogged, compressor itself can do it, energy hog. mine did what yours is doing with the ac on when my ac worked. ive had the dogbone motor mount replaced that helped alot with the vibration. u will see it when u open the hood look straight down behind the radiator. the motor mounts cause alot of flexion when they go bad. oh my torque converter use to vibrate alot before i had it replaced.

check your motor mounts, especially your rear one

- especially of you have urethane type aftermarket motor mounts - they'll shake the daylights out of you and the car, esp w/ the AC on. Needless and dumb mod on a street driven car w/ less than a ton of horsepower & torque. . .

Also - a too low of an idle setting - esp if the relay craps out that ups the idle when the AC is turned on, will shake the car but not necessarily cause it to stall out. . .

Clogged/dirty injectors -esp if one cylinder is worse than others will do the same. Try a can of namebrand injector cleaner - prob needs it anyway.

A fouled spark plug or bad plug wire can also cause rough idle. Bunch of miles on either plugs or wires?- replace them anyway, as they're probably long overdue for replacement. Pull the plugs (reinstall in the same cylinder, but unless almost new, replace them since they're already out of the engine), check that each had a spark plug washer between the plug and the cylinder head, and look for variations in the color, soot deposits, excessive oil, wet from too much unburned gasoline, or an out-of-spec spark plug gap (or even a spark plug w/ cracked ceramic). Are all the plugs the same part#, and the correct ones for your car? (I've seen dumber things happen. . .) Actually do this even before pulling the plugs (too lazy to rewrite in the correct order - lol) Open the hood in a very dark garage, or outside at night (if it's real dark) and look for arcing from one or more spark plug wires. Are the plug wires routed properly, or have they been inadvertenly crossed over adjacent plug wires, creating a 'cross fire' (and bad idle or miss)? Defective plug wires can foul, and even destroy a spark plug over time. btw - OEM Honda wires, are in my opinion, the best replacement wires for a near stock engine. . .Not sexy baby blue or yellow, but they fit better, last longer and consistently work better than almost all aftermarket wires.

How old is the air filter?

Also check your fuel filter - should be on your firewall - follow the directions for removal in the shop manual - and if it hasn't been replaced within the recommended service interval, do that.

Check to see if the PCV valve is functioning properly - remove it and see if you hear a rattle. If not, toss it and get a replacement. While you're at it, inspect all the rubber hoses - incl. those for the PCV valve and any vacuum lines - if not tight, either trim off the mushy or split end if it's long enough, or replace w/ correct type and inside diameter hose - avail by the foot at most decent autoparts stores.

Check out the EGR valve as someone already suggested. (see your shop manual for how to diagnose EGR problems) If it's an original it may have crapped out, or perhaps an faulty electrical solenoid, relay, or an intermittent weak connection could be at fault.

Does it get worse, or only occur, when the engine is hot (or cold)?

All else fails - perform a compression check, for it might be something down in the guts of the engine, such as a cracked piston ring - hopefully, and probably not, as it's a Honda, and properly maintained will last for several hundred thousands of miles - esp 4 cylinder models.

Good luck.

mine does the same.... how expensive are motor mounts?

the two on the sides and the one in the front are about $40 each, but the rear mount is about $200. later.