DTCs

[dargisa17]

So it's been a few months since I plugged in my Hypertech programmer and its been running lean. It produced 7 codes and I'm not sure which to prioritize (in terms of performance) to spend money to fix first:

C0503 - Steering Assist Control Solenoid Return Circuit Low
P0133 - HO2S Slow Response Bank 1 Sensor 1
P0134 - HO2S Circuit Insufficient Activity Bank 1 Sensor 1
P0171 - Fuel Trim System Lean Bank 1
P0300 - Random/Multiple Cylinder Misfire Detected (Generic I can't hear, nor tell if actually misfiring)
P1133 - HO2S Insufficient Switching Bank 1 Sensor 1
P1134 - HO2S Transition Time Ratio Bank1 Sensor 1

Suggestions?

 

[Scottydoggs]

id start with the o2 sensor. thay are all related, the slow response, slow switching, is causing the the lean code and misfires i bet.

when a o2 goes bad it messes up the fueling.

the cat could also be bad, has it felt gutless before all the codes? sound like a vacuum with a full bag when wot?

 

[dargisa17]

I'm going to start with replacing the upstream bank 1 O2 sensor and see what happens, but I don't plan on throwing part after part.

When WOT the truck is slightly sluggish, in terms of a vacuum it more like a bits of tiny gravel in the canister than anything, especially when hitting 4,250 rpm mark before shifting.

 

[iamdub]

I'm going to start with replacing the upstream bank 1 O2 sensor and see what happens, but I don't plan on throwing part after part.

When WOT the truck is slightly sluggish, in terms of a vacuum it more like a bits of tiny gravel in the canister than anything, especially when hitting 4,250 rpm mark before shifting.

Yes- check the circuit (wiring, plug, etc.) for that O2 sensor and check or replace the sensor itself then see if any codes return.

By "gravel in the canister", you mean it makes that type of sound? That sounds like pinging/detonation to me. You may have a weak fuel pump that isn't supplying quite enough fuel for the higher RPMs and it's running lean. Weak fuel supply would explain random misfires, lean exhaust, more sluggish at higher RPM, etc. Also, any knock/pinging detected by the knock sensor would retard he timing, increasing the sluggishness.

I'd suggest checking the fuel pressure (at all RPM) ASAP. If you're running a 93 octane tune, I'd also suggest trying an 89 or 87 to see if the "bits tiny of gravel" sound goes away.