4.3 missfires when warmed up
#1
02-10-2013, 04:22 PM
Join Date: Aug 2012
Location: nova scotia canada,eh
Posts: 27
4.3 missfires when warmed up
runs great cold untill it warms up to operating temp then it starts to missfire/idel rough under wot is the worse it has allmost no power at all at wot, tried new distuibuter cap and wires and going to run the codes tommorw because the check engine light is on but has been since i bought it, and the problem just started!! when i first bought it it ran bad so i disconected the maf sensor and it ran great now about 2 months later this just started hapening after topin it up with supreme at the station.
Any help would be great.
Any help would be great.
#3
02-10-2013, 04:32 PM
Post the codes here in the order they are retrieved. Then check fuel pressure and leakdown and post the results.
#5
02-10-2013, 04:55 PM
Pressure must be 60psi to 66psi while the pump is running, and it must remain above 55psi for at least 10 minutes after the pump shuts off. You can apply battery voltage to the pump prime terminal in the underhood fuse panel to activate the pump while checking pressure:
#6
02-10-2013, 05:06 PM
Join Date: Aug 2012
Location: nova scotia canada,eh
Posts: 27
after it warms up and starts missfireing i shut it off and primed it acouple times with the key by turning it on and off but not starting it and as soon as i start it it missfires right away, leave it overnight in 30degree weather go out and start it and just let it run for 30 minuets or better and unless it is warmed right up to operating tempture it will not missfire and runs good, leave it over night and take it for adrive after 10 minuets its up to full operating temp and it starts to missfire
#7
02-10-2013, 05:29 PM
Post the DTC's and fuel pressure results, that will give us some clues. Without it we can only guess, and that can get expensive 
#8
02-11-2013, 05:36 PM
Join Date: Aug 2012
Location: nova scotia canada,eh
Posts: 27
Only code was mad and swaped it today with one that I know is good and the check engine light is on but I noticed the front 02 sensor closest to the engine rotted off around the exhuast pipe itself, also looks like this has happend right around the missfire could the 02 sensor being out of the pipe and maf combo cause this ?
#10
02-11-2013, 07:12 PM
Very good possibility. Exhaust system can not have leaks for the PCM to control the engine properly.