04 Yukon 2wd 4.8L P0300

[Alphonso Jackson]

I change the spark plugs , ignition coils and wires and still throwing the P0300 code random misfires . Also it's saying that both Catylic converters are bad . What should I check next for the random misfires Autozone is saying that it maybe my Fuel injector pressure regulator can't locate it on the 04 Yukon usual right above valve covers but not there

 

[01ssreda4]

Your regulator is in the tank. Check the pressure at the rail. Look for around 60 psi. Also, consider replacing the cats.

 

[Alphonso Jackson]

Your regulator is in the tank. Check the pressure at the rail. Look for around 60 psi. Also, consider replacing the cats.

Thanks I'm replacing cats on Monday so hopefully I won't have to change regulator but probaly will change that down the line

 

[Chip18]

Your regulator is in the tank. Check the pressure at the rail. Look for around 60 psi. Also, consider replacing the cats.

Just gonna say ... at the tank and 60 psi??? Are you kidding me ... sigh ... lots to learn here.

Might as well ask ... where is the fuel filter???

 

[Chip18]

I change the spark plugs , ignition coils and wires and still throwing the P0300 code random misfires . Also it's saying that both Catylic converters are bad . What should I check next for the random misfires Autozone is saying that it maybe my Fuel injector pressure regulator can't locate it on the 04 Yukon usual right above valve covers but not there

LOL ... I think, I just expressed your surprise!

 

[Chip18]

Hmmm back on pointe ... I belive you can check the O2 sensors with a "DVOM" look for voltage fluctuations rapidly .... ECM should try and maintain a 14.7 AFR. If it's slow to respond a bad O2 sensor(S) could be the culprit??

Not saying it's not bad cats but ... it couldn't hurt to check the O2's.

 

[01ssreda4]

Just gonna say ... at the tank and 60 psi??? Are you kidding me ... sigh ... lots to learn here.

Might as well ask ... where is the fuel filter???

03 and down its on the frame rail, 04 and after its built in to the intank assembly, meaning non replaceable.

 

[Chip18]

03 and down its on the frame rail, 04 and after its built in to the intank assembly, meaning non replaceable.

Aww ... the "funny screen" around the pump thing!

Seen that older cars seem to have both??? But thanks most likely you saved many hours of looking for something that is not there!