Plugged converter=truck DOWN

[AKlowriderZ71]

Well, at 109,500 miles, it finally happened. I was WOT to pass someone, and at 4000 RPM, the engine started pinging BADLY, SES light came on, truck wouldn't accelerate. Got back to work and scanned the PCM, had P0300 random misfire code. Test drove it with the scanner, all the misfires were on #3. I decided to replace #3 spark plug, swapped the wire to #1, swapped the coil to #5, test drove again. Still not fixed, still misfiring on #3. Tested fuel pressure and did injector balance test, fuel pressure 5 PSI below spec, but #3 injector inop on 3 different tests. No noise from injector when commanded to pulse, and no pressure drop. So I replaced #3 injector and test drove, SES flashing now, less power than ever, will not accelerate past 45 MPH, and pings at any throttle angle. Tested exhaust backpressure and found 3 lbs backpressure on Bank 1, 1 lb backpressure on bank 2, at 500 rpm. Spec is less than 1 lb at 3000 rpm, so I've ordered a new converter. Should be here in a couple of days.

[r6z4o6]

Unscrew the upstream O2's if they are aimed safely away from wires/plastic/melty things and it should be loud and fast while you wait for your cats.

[AKlowriderZ71]

I'm just driving the company truck until it's fixed. I'm not in too big a hurry. Still wondering if the 5 psi low fuel pressure will be an issue for me. I have a plan if it is.

[Ramsey]

50 - 58 will do just fine on the f/p.

[AKlowriderZ71]

OK, new cats are on, problem has been fixed.