Hi guys 2004 Tahoe po300

[mikelouf2]

2004 Tahoe 24600 on it 5.3 keep geting a po300 code. New spark plugs new wires and coil packs. I think the after market cat is no good put it on 3 yrs ago I was getting. A po420 a long time go i did here sometime rattle in there a long time ago. With the live data look like the 02 sensor where flowing each other

 

[Fless]

Moved you here from General Discussion since this is a Engine & Drivetrain issue.

?? So the mileage is 24,600; or did a zero get dropped and it's 246,000 miles? Kilometers?

MAF rate at idle seems to be okay at 0.7 lb/min (that converts to 5.3 g/sec, which is easier for us to understand without having to convert the value).

I would recommend checking the fuel pressure (KOEO first, then with the engine idling).

Cam or crank sensor ever been changed? Also has a CASE relearn been done recently? If not, do that with a capable scanner just to rule it out.

 

[mikelouf2]

Moved you here from General Discussion since this is a Engine & Drivetrain issue.

?? So the mileage is 24,600; or did a zero get dropped and it's 246,000 miles? Kilometers?

MAF rate at idle seems to be okay at 0.7 lb/min (that converts to 5.3 g/sec, which is easier for us to understand without having to convert the value).

I would recommend checking the fuel pressure (KOEO first, then with the engine idling).

Cam or crank sensor ever been changed? Also has a CASE relearn been done recently? If not, do that with a capable scanner just to rule it out.

I change the crank sensor a while ago not the cam. The fuel pressure is ok.

 

[Fless]

I'm not sure what "ok" means for the fuel pressure. If the FPR is allowing too much pressure (i.e., not regulating) it can cause random misfires.

Since you changed the crank sensor, do the CASE relearn with a scanner so that's ruled out as the cause.