1993 350 TBI Rough idle and low range

[348tripower]

Ok folks take a shot at this one.
 I have this rough idle and rough mid range. When ya lean on it it smooths out the faster ya go. I am thinking cap rotor wires etc. because I don't know when it was if at all done. 70 thousand on the clock. It started this after being really low on fuel. Maybe fuel filter? The other thing is that it ran perfect all the way to Muskegon and back in the rain. Sets over night and it is rough. I think I will get out the WD40 tonight and see what happens.
Don

[mopar2dr]

Check your EGR valve. If it is bad or stuck open, your idle and low range rpm will rough. Mine was stuck open, just required some WD 40 and a few times with the Mighty-Vac. If your getting black smoke and flooding it could be the temperature sensor. That caused my rough low end and killed my milage.

[wayne petty]

check for vacuum leaks at the intake manifold gaskets...   look for coolant leaks at the 4 corners...  these have weak gaskets also...

if you pull the cap and rotor...    take a bright flash light.. look straight down where you pulled the rotor off.. there is the steel reluctor riveted on.. exposed just a tiny bit at the center is a ceramic magnet... if you see cracks... you need to replace the distributer...

reman units with a MUCH upgraded pickup coil and a totally different design reluctor are available at autozone for 100 bucks..

why...

cracks in the magnet create random low voltage seine waves that the module and the ECM see and it throws the electronic spark timing off..  .. remember these look at the milliseconds between timing pulses and calculate how long to hold back the spark... when these random signals get sent out.. it will cause the spark timing to jump around and throw sparks at totally the wrong time..

wiggle the shaft also... on the old one.. i have seen them so bad they were noisy as they were hitting the tips of the reluctor to the tips of the pick up coil...


here is a picture of the top of the new design distributer..

http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/c11/30-1830/2/image/8/

if you have to replace it... remember this image.. compare it to the OEM one you are taking out..  don't waste money on an OEM riveted design..


also.. don't worry if the module says transpo.. it is a quality unit..