hey everyone i have a lowish rpm misfire/stumble, normally happens on take off and under just about every throttle condition up until about 2000 rpm sometimes even more , had a fuel pump going bad replaced it and was hoping to call it a day, not the case though. So today i changed spark plugs even though the old ones looked good, checked wires didn't seen any burn marks none were loose, unplugged maf no difference. Took it for a short drive to let it warm up. the plugs seemed to help i think could also be fact i haven't driven it in a couple days to, so while i was taking it for a spin i noticed when my sputter/misfire happens my ignition timing get retarded a lot cruising without misfire i see as high as 44* of timing around 29-30* idle and misfire happens i see about 19-24* of timing, what could cause this, i don't wanna just start replacing everything and unfortunatley im not in a position to just troubleshoot all day long right now.

 

Sounds like what I had, small vacuum leak, it was the bottom hose for the opti had been cut.

 

thanks ill check that tomorrow, i was thinking opti because it got worse the other day when driving in the rain even though i didn't hit any huge puddles, but recently remember that its had this problem in 5th and 6th at real low rpms for a while now its just all gears.. anyone else have any ideas

 

to the top, took just a quick look at the hose on opti from engine bay it looks good, need to jack the car up and look under neath but what else could cause my timing to dip into low 20s, when it should be at high 30s getting on the throttle. im also getting misfire cel flashes from time to time no code though for i think it was tuned out.... out of ideas car makes me want to pull my hair out, because now i need to fix this and the numerous oil leaks i seem to have developed

 

You should put a scanner on it to see what your knock sensor is doing.

 

i want to but unfortunatley my live scanner doesnt have gm parameters... which really sucks, and with the car being a 96 its really hard for me to find someone with a scanner for obd2 that reads gm parameters, would a knock sensor cause misfires

 

also driving today i realized 6th gear about 2k rpm or so under throttle i let off and have huge backfires sometimes

 

ttt anyone know of an easy way to read knock counts on obd2 lt1? that doesn't cost a fortune