'97 Vortec 350 Engine performance

[EyeSac]

I have a 1997 K1500 Silverado with the 5.7 Vortec engine. For the past 2 months I have been battling this truck. The problem I'm having is that after 30 minutes or so of driving to work it starts misfiring and backfiring. The whole vehicle shakes and looses power. I've found then when this happened, the spark plugs in bank 2 are completely fouled with carbon. The temporary solution I've come up with is to clean the plugs in bank 2 with brake parts cleaner and a brass wire brush before I leave work. After I do that it runs fine, just like it's supposed to. Something keeps fouling the plugs in bank 2 and I can't figure it out. The only codes I have on the vehicle are:

P0154 - O2 sensor Bank 2 sensor 1 no activity
P0158 - O2 sensor Bank 2 sensor 2 high voltage
P0161- O2 sensor Heater circuit Bank 2 Sensor 2

The truck does not have any cats on it. Could someone help me get to the bottom of this?


Here is everything I've done to the truck while trying to fix this issue:

Cleaned the carbon out of the throttle body and upper intake plenum

Distributor cap and rotor

Spark plugs and wires

Multiport fuel injector upgrade

Fuel filter

Mass airflow sensor

Crank position and cam position sensors

I have new coolant temperature sensors in the mail, not installed yet

 

[EJ_74]

Looks like your problem is right there in the codes listed. The front O2 sensors (B1 S1 and B2 S1) are what control your fuel mixture. The rear ones just monitor the cat. Even though you have no cats you still need the front sensors. The computer isn't receiving any activity on bank 2 so it's not able to meter fuel properly on that side. Check the wiring but may just need a new sensor. They get old and don't perform as well over time

 

[EyeSac]

Looks like your problem is right there in the codes listed. The front O2 sensors (B1 S1 and B2 S1) are what control your fuel mixture. The rear ones just monitor the cat. Even though you have no cats you still need the front sensors. The computer isn't receiving any activity on bank 2 so it's not able to meter fuel properly on that side. Check the wiring but may just need a new sensor. They get old and don't perform as well over time

If I were to replace the problematic O2 sensor, is just the one okay or should they be replaced in pairs?

 

[JDGMC]

You don’t have to replace it in pairs, but I would recommend you replace both. Depending on mileage and condition of the engine you may need to anyway. The other reason is they become more difficult to remove with time.

 

[EyeSac]

You don’t have to replace it in pairs, but I would recommend you replace both. Depending on mileage and condition of the engine you may need to anyway. The other reason is they become more difficult to remove with time.

Okay I will work on replacing just the one sensor for now since I'm a little low on cash at the moment but I will get to the other one eventually. I've heard the best way to remove them is a blowtorch and some Kroil, is this true?

I appreciate you guys for the fast response by the way, I should have done this way sooner

 

[Schurkey]

If I were to replace the problematic O2 sensor, is just the one okay or should they be replaced in pairs?

If you don't know how old they are, they should ALL be replaced. You need four sensors, and a couple of catalysts.

I've heard the best way to remove them is a blowtorch and some Kroil, is this true?

Heat from an oxy-fuel torch can be very beneficial. Regular propane without added oxygen is likely one step away from useless.

Penetrating oil is not going to be effective. The sensor is sealed to the exhaust system with a gasket, similar to the older spark plug gaskets. They provide an air-tight seal. Exhaust can't leak out, penetrating oil CANNOT get in. It will make a lovely stain on the concrete under the truck, though. Penetrating oil is useless at least until the sensor is backed-out enough to break the gasket seal. But once the sensor is backed-out...it's no longer seized.

Beware that O2 sensor threads often gall the female threads in the exhaust system. VERY common to have to re-form the threads before the new sensor goes in. And the new sensor MUST have anti-seize on the threads.