Hello first time posting here. Have a 99 suburban k2500 7.4.
Bought in 2015 with 136,000 miles.
Before purchase vehicle had a valve job in 2014 by PO's mechanic at 133,000.
Ran rough during test drive in 2015, PO's mechanic "turned up idle", I then purchased vehicle.
Has never thrown a code for the idle.
Twice since then have had rough idle and fuel rich exhaust odors. Cam sensor and new distributor solved once 2 years ago, this recent time it has not. Did have timing set at a dealer both times distributors were changed.
Recently a couple shops read codes and I have replaced the following after visually inspecting all wiring and connections to these sensors-
-cam sensor and distributor (new metal dist. from NAPA)
-lower knock sensor and wire harness. Is there another knock sensor on top of motor?
-both upstream O2 sensors
-temp sensor by thermostat
No change in the rough idle or fuel rich exhaust odors.
Besides the crank sensor, any ideas?
Still has the cats, though they are dead.
Thanks for any insight.
Attached are the codes read before the above sensors and distributor change was performed-
Bought in 2015 with 136,000 miles.
Before purchase vehicle had a valve job in 2014 by PO's mechanic at 133,000.
Ran rough during test drive in 2015, PO's mechanic "turned up idle", I then purchased vehicle.
Has never thrown a code for the idle.
Twice since then have had rough idle and fuel rich exhaust odors. Cam sensor and new distributor solved once 2 years ago, this recent time it has not. Did have timing set at a dealer both times distributors were changed.
Recently a couple shops read codes and I have replaced the following after visually inspecting all wiring and connections to these sensors-
-cam sensor and distributor (new metal dist. from NAPA)
-lower knock sensor and wire harness. Is there another knock sensor on top of motor?
-both upstream O2 sensors
-temp sensor by thermostat
No change in the rough idle or fuel rich exhaust odors.
Besides the crank sensor, any ideas?
Still has the cats, though they are dead.
Thanks for any insight.
Attached are the codes read before the above sensors and distributor change was performed-
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