99 Yukon P0420 with new parts

[_matt]

the truck has gone through a good bit of repair recently yet out of nowhere BAM, this mofo throws P0420. i am hoping that you guys could help me come up with some ideas on things too check. Recent work done includes the following:

• ALL Oxygen Sensors
• Catalytic Converter's
• #4 & #6 Intake & Exhaust Valves
• All Valve Seals
• Plugs, Wires, Cap, Rotor
• Water Pump
• Radiator
• Upper & Lower Radiator Hose

All the work was done by a friend and myself execpt for the CATs, that was done by a local shop. Had a timing issue upon reassembly, but finally got it set too -1 with the help of a scan-tool. What live data should I be looking at too diagnose this fiasco?

 

[2000tahoeZ71]

You want to look at the pre and post cat o2 sensors. If i recall correctly the pre shoud stay stable, and the post should fluctuate up and down. Did you use ACDelco o2s? I had the same code and replaced all 4 with ac delcos and the magnaflow cat assembly and all has been good.

 

[_matt]

Yes, the O2 sensors are ACDelco and obtained from the local GMC dealership. I do not know the brand of the catalytic converters that the Exhaust Shop used. i will be looking at those readings tomorrow and will post the results.

 

[_matt]

Sensor Available
Bank 1 - Sensor 1 Yes
Bank 1 - Sensor 2 Yes
Bank 1 - Sensor 3 No
Bank 1 - Sensor 4 No
Bank 2 - Sensor 1 Yes
Bank 2 - Sensor 2 Yes
Bank 2 - Sensor 3 No
Bank 2 - Sensor 4 No

Sensor Description Value Minimum Maximum Units Result
Bank 1 - Sensor 1 TID $01 - Rich to lean sensor threshold voltage (constant) 0.445 0 1.275 V Pass
Bank 1 - Sensor 1 TID $02 - Lean to rich sensor threshold voltage (constant) 0.445 0 1.275 V Pass
Bank 1 - Sensor 1 TID $03 - Low sensor voltage for switch time calculation(constant) 0.295 0 1.275 V Pass
Bank 1 - Sensor 1 TID $04 - High sensor voltage for switch time calculation(constant) 0.595 0 1.275 V Pass
Bank 1 - Sensor 1 TID $05 - Rich to lean sensor switch time (calculated) 0.032 0 0.124 sec Pass
Bank 1 - Sensor 1 TID $06 - Lean to rich sensor switch time (calculated) 0.016 0 0.124 sec Pass
Bank 1 - Sensor 1 TID $70 - Manufacturer Defined 190 20 255 counts Pass
Bank 1 - Sensor 1 TID $71 - Manufacturer Defined 213 20 255 counts Pass
Bank 1 - Sensor 1 TID $81 - Manufacturer Defined 57 11 159 Pass
Bank 2 - Sensor 1 TID $01 - Rich to lean sensor threshold voltage (constant) 0.445 0 1.275 V Pass
Bank 2 - Sensor 1 TID $02 - Lean to rich sensor threshold voltage (constant) 0.445 0 1.275 V Pass
Bank 2 - Sensor 1 TID $03 - Low sensor voltage for switch time calculation(constant) 0.295 0 1.275 V Pass
Bank 2 - Sensor 1 TID $04 - High sensor voltage for switch time calculation(constant) 0.595 0 1.275 V Pass
Bank 2 - Sensor 1 TID $05 - Rich to lean sensor switch time (calculated) 0.032 0 0.124 sec Pass
Bank 2 - Sensor 1 TID $06 - Lean to rich sensor switch time (calculated) 0.02 0 0.124 sec Pass
Bank 2 - Sensor 1 TID $70 - Manufacturer Defined 152 20 255 counts Pass
Bank 2 - Sensor 1 TID $71 - Manufacturer Defined 178 20 255 counts Pass
Bank 2 - Sensor 1 TID $81 - Manufacturer Defined 47 11 159 Pass

Name Continuous Available Complete
Misfire Yes Yes Yes
Fuel System Yes Yes Yes
Components Yes Yes Yes
Catalyst No Yes Yes
Heated Catalyst No No No
Evap System No Yes No
Secondary Air System No No No
AC Refrigerant No No No
Oxygen Sensor No Yes Yes
Oxygen Sensor Heater No Yes Yes
EGR System No Yes Yes

 

[_matt]

Attached is a zipped datalog that has a whole bunch of data.