Help! 1994 mustang - rough idle, white smoke pushing out the exhaust pipes.

andy_mustang94 · 03-31-2009

I ran out of fuel and was lucky enough to get to the gas station. the engine was really clunking and misfiring it seemed. so i put in some gas and started it up thinking the problem would be solved. instead, it still ran rough and white smoke would thrust out of the left exhaust pipe only. the 'Check Engine' light came on aswell. i figured that i needed to just open up the throttle and help get the fuel to reach the engine again. i drove home (10 miles) and the engine was rough the whole way. when i would reach an RPM of about 3,000 or higher, the engine would smooth out and run fine. when i came to stop signs, the sound from my exhaust would be different and still rough.

the next day, the car is still smoking.. this time, out both the exhaust pipes. the 'check engine' light went away. but the smoke has some heavy scented gas smell. it sprays gas, and what seems to be oil aswell.

what may be the problem? any suggestions? maybe my fuel filter might of sucked up gunk in the tank? i do have 215,000 miles on it. lol

thanks,
Andrew

StalkerStang · 03-31-2009

Sounds like an injector stuck open.

Its somewhat common on the 94/95 cars. When my old 94 did it, I had to replace the PCM, the driver in the PCM burned out.

If you have access to a fuel pressure guage, you can find out which one it is pretty easy. Or if you have a scanner, it should tell you what cylinder it is.

Don't continue to drive it though until its fixed. Raw fuel can kill your cats and O2 sensors, and worse, hydrolock the cylinder.

andy_mustang94 · 04-12-2009

so i got some used and cleaned fuel injectors for a low price, and got new sparkplugs and plug wires and everything installed. i did a compression test, each plug hole was at 150-160. i changed out my fuel filter and cleaned the fuel lines. after installing everything on, i go to start it up and its still at the same position as before. white smoke flying out of the exhaust pipes. (there is more smoke on the left pipe than the right..) you were talking about the driver of the PCM possibly being burnt out?

StalkerStang · 04-12-2009

Yes, the injectors have power supplied when the ignition is on, and the PCM pulses the ground, the transistor can be bruned out, causing the ground to be switched on at all times.

Its really easy to find the culprit with a fuel pressure guage if the check engine light hasn't come on yet. More then likely its in cyl.'s 4-6 (left bank).

If you unplug all the injectors on the driver side bank, hook up a fuel pressure guage, turn the ignition on (don't start it), verify the fuel pressure is holding (usually 30-40 psi), then one by one plug in the injectors on the left bank while you monitor the fuel pressure guage. As soon as the pressure drops off, note which one you plugged in, more then likely that driver in the PCM is burned out.

andy_mustang94 · 04-16-2009

Alright, so i bought a new, used, and good conditioned computer with the same codes and everything. i took out the old one and installed the new one in. i started the car up and immediately after starting, the engine sounds great. no more rough engine or sound. the exhaust sounds good.

but just one problem, there was still white smoke coming out. this time there wasnt much gas odor like before..hardly any at all. i took it around the block twice and opened the throttle up a bit. the smoke seemed to be calming down a lot. i hope its just smoking due to the residue from the last time i started it.

StalkerStang · 04-16-2009

Yeah it will push out smoke still until all the raw fuel gets out of the exhaust. If you can afford it, you may want to look at getting some O2 sensors.

The raw fuel can contaminate them, hopefully it hasn't fried the cats at all.

andy_mustang94 · 04-16-2009

Well thanks a lot man. You were tons of help for me and i appreciate that!

StalkerStang · 04-17-2009

Yeah no problem, glad I was able to help.