1993 Buick LeSabre runs rough, engine shakes, low rpm. 117,500 miles.

awj53

I was sitting in traffic last night when all of a sudden the engine rpm dropped and the engine began to run rough and vibrate badly with a puttering exhaust sound.
Started the vehicle today and the same thing, except for higher rpm’s where the engine seems to smooth out and run ok??
Exhaust smells stinky, burning, no out right rotten egg smell though.
My wife stated she could smell a slight sulfur smell?
Any ideas??

Thanks: AJ

Mr_Shiftright

Sounds like a misfire to me---spark plug cables, fouled plug, etc.

You might buy yourself a simple spark detector and go from there.

You can also perform a cylinder balance test.

thecardoc3

With a 93 Lesabre, the easiest way to do a cylinder balance test (prove what cylinder is misfiring) is to get the engine to idle at a steady speed, and disconnect the idle air control valve. Then disconnect and re-connect injectors one at a time and watch the engine for changes in the way that it is running. Any injectors that you disconnect that DO NOT change the way the engine is running are the cylinders that are misfiring and the ones you will need to test to prove why. (lost spark, fuel, compression etc.)