engine skip in 1991 5.0

Brian47p · 09-23-2007, 01:22 AM

i got a 91, 5.0 5 speed in great condition
only thing changed are an electric fan , air intake and mufflers. The engine skips and cannot find out why. i just recently have found out my catalytic converters may be gone. does anyone know if that could cause the engine skip because ofthe wrongback pressure?

mjr46 · 02-02-2008, 03:24 PM

Quote:

ORIGINAL: Brian47p

i got a 91, 5.0 5 speed in great condition
only thing changed are an electric fan , air intake and mufflers. The engine skips and cannot find out why. i just recently have found out my catalytic converters may be gone. does anyone know if that could cause the engine skip because ofthe wrongback pressure?

cats missing will not cause misfire..run a koeo/koer test/ cylinder power balance test to see what cyl in not producing power and is the misfire present always..or under load??

Brian47p · 02-03-2008, 06:06 PM

my cats arent gone gone, they just need to be replaced , i think they are all clogged up. my theory is that the engine is choking out because it cannot exhuast because it is too clogged up. it gets worse as the car heats up, which makes me think its the cats heating up. any thoughts on this? any tests i can run to figured out of its this? because so far electrical all checks out.

mjr46 · 02-03-2008, 08:29 PM

^^^^^^^^^^......if that's the case before you waste money then either remove o2 sensors to allow excess back pressure to escape and go for a ride..if it drives alot better after removal then you have the issue solved..if not back to the drawing board

Brian47p · 02-03-2008, 10:16 PM

thanks alot man, thats the first time iv heard that and i have tried everything. i will definatly try that and i will let you know. its gonna be a few months before i go back home to drive it again though.

nitrousd85 · 02-03-2008, 10:29 PM

dont you think it will run like **** w/o o2's pluged in ?????????
wheee

mjr46 · 02-03-2008, 10:44 PM

no it won't run like crap cause what do you think the car is running on when it's in open loop??...not the o2's..they don't come into play until closed loop operation once car is warmed up.....besides your only doing this for diagnostic purposes.....in fact you can loosen the pipes at the connection if you don't want to remove the o2's........done it many times to diagnosis a plugged cat condition....in fact on a 92 motor home with a 460 we took the o2 completely out and screwed in a vaccum/pressure gauge to check back pressure