had bought my daughter a 91' lumina w/3.1. For the last several months it has been acting up, it will stutter and stall, it will do this whether engine is hot or cold but will not do it with any rhyme or reason. r/r fuel pump that didn't help, tapped on ecm while running to see if it would die, it did not. her boyfriend and his father removed catalytic converter cause it was all melted inside and car seemed to run ok. he drove to our house yesterday and all was fine till he went to leave and it started it all over again. car died and would not start, it would turn over and sput now and them but would not start also smelt combustion smell. I went out this morning and has started and ran fine in the drive. have shut off and restarted several times. Does anyone have any ideas on this?
If it has ran smooth since the converter was removed try the ignition. Next time it wont start pull one or some of the plugs and check for a strong blue spark. The ICM is behind the coil packs and they do see a lot of heat being that close to the exhaust.
got vehicle to act up today, too light out to see spark but engine had a constant surge when stepping on gas. when under 3/4 throttle it would surge in a very consistant timing. it however did not spit or sputter