taylorb71
TYF Newbie
I bought a 2000 suburban 4x4 5.3l mainly for parts to ls swap my square body but I want to get it running decent in the vehicle so I’m not trying to diagnose it in my square body.
problem I’m having is a po300 code. At idle the check engine light will blink and it runs rough and almost sounds like lifter clatter but I’m thinking it’s spark knock because some times it will run fine and the engine sounds normal!
I’ve crudely checked each coil for spark and each spark looks nice and strong, spark plugs are good as well.
I have a feeling it’s a fuel issue as I bought it with a full tank of gas and the kid said it ran like crap. I poured a thing of Techron (or whatever it is) fuel treat and ran a half a bottle of sea foam through the pcv hose. I’m not sure if it’s made a difference or not. When I throttle it, it sounds super throaty through the intake (factory and not restricted) but taps out at about 4K rpm and takes a while to get there.
fuel pressure is good with 49psi at idle and 58 psi when I give it throttle.
when I hook my scanner up to it my o2 sensors are switching like they should when it gets to closed loop although the downstream sensors seem a little goofy. My fuel trims also seem weird. Stft1 is at -11% and stft2 is around 0%.
Map sensor is reading 11hg
Maf is reading 1.04lb
Iat and coolant temp seem to be accurate.
I’m just kind of lost. I’m thinking the fuel trims is telling me something but I don’t have much experience with values on a scan tool. Also having the downstream o2’s acting goofy by switching more than they should kind of leads me to a plugged cat or 2 as well.
I’m sorry for the huge post just lost lol
problem I’m having is a po300 code. At idle the check engine light will blink and it runs rough and almost sounds like lifter clatter but I’m thinking it’s spark knock because some times it will run fine and the engine sounds normal!
I’ve crudely checked each coil for spark and each spark looks nice and strong, spark plugs are good as well.
I have a feeling it’s a fuel issue as I bought it with a full tank of gas and the kid said it ran like crap. I poured a thing of Techron (or whatever it is) fuel treat and ran a half a bottle of sea foam through the pcv hose. I’m not sure if it’s made a difference or not. When I throttle it, it sounds super throaty through the intake (factory and not restricted) but taps out at about 4K rpm and takes a while to get there.
fuel pressure is good with 49psi at idle and 58 psi when I give it throttle.
when I hook my scanner up to it my o2 sensors are switching like they should when it gets to closed loop although the downstream sensors seem a little goofy. My fuel trims also seem weird. Stft1 is at -11% and stft2 is around 0%.
Map sensor is reading 11hg
Maf is reading 1.04lb
Iat and coolant temp seem to be accurate.
I’m just kind of lost. I’m thinking the fuel trims is telling me something but I don’t have much experience with values on a scan tool. Also having the downstream o2’s acting goofy by switching more than they should kind of leads me to a plugged cat or 2 as well.
I’m sorry for the huge post just lost lol