shaking

[5.0homustang]

just bought a 94 5.0high output mustang. only probelm with it is that the whole car shaked really bad especially the motor. did a tune up(plugs wires cap and rotor) no improvement. also did a compresion test and it came back all fine. any of you other guys have this problem? any idea what it might be?
thanks for any and all help

[Zim]

Could be the harmonic balancer... an easy way to tell is crawl under the front of your car... look at the balancer (its what your crank pulley attaches to) then look for any black rubber popping out of it anywhere.


Does it shake all through the gears and powerband? Does it do it when you just rev your motor when its not in gear? Little more info on it... how violent is the shaking, etc.?

[Brent]

Motor mounts?

[5.0homustang]

it does it at idle when you rev it up it does it constently. someone told me maybe the flywheel?? dont know about that

[bbunt302]

Quote: Originally Posted by Brent Motor mounts?

That would be my first guess.

[MonteCitan]

I know mine shakes badly at idle.. but with the cam its like idling with a dead miss on 3 cylinders, and I'm using poly motor and trans mounts .. but hit the gas at all and it smooths right out..

Some ideas : motor mount, trans mount.. If its a manual.. your car could have puked a flywheel weight, if its automatic it could be the torque converter

Check your balancer, make sure there's no mud or crap caked in the pulley.. or any of your pulleys at that... remove the belt, and with your hand check to make sure all the pulleys are tight and spin as they should (IE power steering pump should have some resistance but should not make noise and should have close to no in/out motion..)

Also try unplugging the wires one at a time (expect to get zapped now and again, would help to use spark plug wire pliers..) if the way the motor runs changes with each wire you pull, then its likely not (at least not a dead cylinder) a misfire..

It could still be a lean condition (lack of fuel?) causing it but revving it up a little would usually clear this up (esp as it revved back down to idle)


if your flywheel is warped too badly (from heat/damage.) that could also affect it, if its a flex plate (auto trans..) it could be cracked..

that's where I'd start...