Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
1996 Impala SS LT1 (Intake backfire) PART 2 live graph of the 02 sensors.
Bank one sensor two looks like its stuck lean however your temp gauge suggests its not warmed up to operating temp. You may need to check the bias/supply voltage at pcm and at o2 sensor to see if its dropping at some point in harness. Also make sure its warmed up as the rear o2s need it warmed up to function as designed.
you could check reaction time for a lean (create a vacuum leak) or rich (add fuel like propane to intake) condition and see if it reacts and how fast as well as re-stabilization time. It should react very quickly for upstream and downstream should react a little after that.
I would say that sensor is dead then also from the graph might need a upstream sensor on bank 2 as well. But replace b2s2 first then graph them to see if upstream improves.
ok that is good to hear in a sense. i take it your car has a true dual exhaust?... what kind of condition is the catalytic converter in for the effected bank?
With that info i would say to put the scope camera down the intake and see if there is carbon buildup on the intake valves.
The way to check for a cat problem ie plugged/restricted cats is to take upstream sensor out and thread in an adapter hooked to a low pressure gauge 20 psi or less with a vac hose or a piece of brake line . These gauges are in a carborated fuel pressure test kit plus they have a vac readout on them as well and they are not expensive as well. Then once its hooked up start the car and see what reading is at idle then at higher rpm. The pressure should not exceed 2-3psi if it goes over that then cat is restricted. Repeat test for each side. Let me know if you have any issues etc.
Ok that's a good thing cats are not cheap. Now I also noticed in the pics you provided that your knock sensor counts were around 6000 as well as codes for intake air temp and coolant temp sensor as well as both downstream sensors have codes for the heater circuit. I would say to focus on the iat and ECT sensors as those will cause a rich and or lean condition so be sure to check wiring for proper voltage on vref. also check ground for less than 200 MV with key on engine off. Then the signal wire should read low mv when cold and increase in voltage as it warms up. You will also want to do a resistance test with a ohm meter and see what the resistance is compared to temperature of air (iat) and coolant(ect).
Topic Author
