USMCghostReaper

i have a 1991 mustang lx that is a 4 cylinder but has 8 spark plugs. my car shakes real bad at idle and while driving. it has no power and takes me forever to get up to 30mph. i replaced the ignition coil, mass air flow sensor, all new spark plugs and wires and i dont know what else to do. i took it to tires plus and they didnt know what was wrong and they put it on the machine and gave me a couple codes so i changed the parts and still nothing. i need help bad

mikerp76

you may need to replace the cat. my 93 is doing the same thing as well. the front cat melted down and cloged up teh rear cat. SEMPER FI.

91mustangboi

Did u replace the harmonic balancer I had a 92 tempo an wat your going through sounds like my tempo i replaced it runs like new

bl817

i would also take off the idle air control valve (back side of throttle body) and clean that real good with TB cleaner. also check your throttle position sensor (TPS) voltage. it might need adjusted as well. just do a search on here or another mustang forum and youll find all the help you need. another thing might be your egr valve or possible vacuum leak.

mikerp76

this engine doesn't have a harmonic balancer.

91mustangboi

O I didnt no that wat bout the motor mounts that was another thing that was makin my motor shake on my tempo

mikerp76

bad motor mounts a cylinder misfire, bad fuel, fuel injectors, and any electrical problem that controls the various sensors on the motor.

Babybudistmonk

So sounds like you already spent $100's on parts that did you no good. How about we slow down a little bit and test some of these sensors before you needlessly go out and start replacing them.

By now it sounds as if your DIS module is going bad.

Dancan

Good day all,
these are great posts. I have a '88 that idles rough in these conditions: In Drive (or reverse) brake pedal pressed, A/C on or off. notes: my Fan module relay has been bypassed in the system, my RPM is about 1000, i have throughly cleaned out my EGR Valve, and the whole intake through system, to include the EAC valve (sp?). in any case the engine runs fine at all driving speeds. I have replace and gapped all plugs, wires, and cleaned distributor cap contact pooints. FYI all Plugs (4) were even in color and debris, none were wet, black or corroded.

i do not think this car has the DIS as mentioned earlier, don't know what a "cat" is that melted on one posters car.

Any help would be appreciated - thanks - Dan

mikerp76

cat is short for catalitic converter.