Friends 92 celica
 

My friends 92 celica vibrates like hell when its idling. It gets a little better in neutral and it gets a little better if you turn the a/c off. and it stops vibrating when you start driving. any ideas?

A tune up.

change the plugs

ie. tune up

Considering it's age, I'd give it a tune up a little more thorough than that. Spark plug wires, cap and rotor, spark plugs, fuel filter, an intake "cleansing", such as the use or combination of a can of throttle body cleaner (I use Valvoline), B-12 ChemTool Total Fuel System Kit, or SeaFoam, and a good fuel system cleanser to pour in the tank.

Do this all at once when the car is ready for it's next oil change. I also recommend an engine flush. You can also take it a step further with the flush too. After you do the flush, refill oil with an inexpensive brand, minus one quart, and substitute it with a quart of ATF. Drive 50-100 miles then change the oil again to the usual brand.

DO NOT USE THE ATF TECHNIQUE ON TURBO CHARGED VEHICLES.

I did forget to mention, the car only has 40,000 miles on it.

Regardless of miles, some of those components are simply old.

^^Yep, I see this problem every day at the shop. I suspect that the intake system has some carbon build up. Do the intake cleaning like mentioned above, THEN put in new sparkplugs, and oil change.
Also the fuel injectors are probably dirty, and possibly leaking. Thats may be why it runs better once you drive it.

Forgot to mention that order. You don't want to foul your new plugs. Good catch. http://www.toyota-supra.info/forums/...ons/icon14.gif

is it automatic?

Yea auto, u r psychic suprra_girl. And mrnickleye, how can i tell if the injectors are leaking, if that is the case?

well i'm not sure where it is exactly

but i'm thinking the idle up thing for the auto when you change from N to D etc is defective

Mrnickleye... does this item exist? i should imagine it does... would that be in the nsw or auto ecu?
got the same prob on a nissan bluebird but it still runs fine just vibrates like hell lol

Well...is the vibration due to low idle in gear? Outa gear?

The ECU (computer) recognizes when car is in gear and adjusts idle through the ISC (idle speed control) valve. (This may be called something else in the Celica, but its the same thing).

The vibration could be caused by 1 or 2 cylinders with poor spark. Pull wires one at a time while idling to see if a cylinder is weak, and does not make the engine act rough. (good ones make the engine run rough when the wire is removed. Don't shock yourself, use special pliers)

But more likely a fuel or air issue. Perhaps a vacuum leak. Most vacuum leaks only effect 1-2 cylinders, and then usually at idle.

Check that all the vacuum hoses are ok. Then, while idling, spray some brake cleaner along the intake manifold at the head, and other gaskets on it.

You have to do a fuel pressure test to see if an injector is leaking.

Do the other stuff first, cause you might solve the problem. If not, then a shop is best equipped to test the fuel system.

checkthe unis in the drive shaft:)