1997 5.9 4WD, Hughes Airgap, Fastman 50mm, 206/212 cam,LT Pacesetters, MSaine Trans 35K on rebuild


I got a code for an upstream O2 sensor, replaced it and had to have a new bung welded. All is well for 2 days, then I get a downstream 02 sensor code. Grab another O2 sensor, replace it. All is well for 2 days, got another code today and can only assume it's an O2 sensor, going to get it checked today. The old O2 sensors were about a year old. I fired the truck up in the garage and noticed my muffler spitting out some back soot and smelled pretty rich (Normal for a cam?). I'm over throwing parts and trying to actually diagnose. Is my Cat causing an O2 sensor failure? I think unrelated, but I just replaced heater core, radiator, and fan clutch. Any ideas? Both O2 sensors had a LOT of buildup on them.

 

What brand of O2 sensors?

 

has the plenum been fixed? And as dbbd1 asked, what brand sensors? If they are bosch, that's most of your problem right there, our trucks don't care for them. NTK, or Denso please.

 

Hughes Airgap intake, no plenum gasket. Bosch spark plugs from autozone....pulling them out today, gonna swap tomorrow. Thanks for the help gentlemen.

 

The stores are telling me they can get NGK, was that a typo? If not does anyone have p/n's for NTK

 

Did you bother to clear the codes and reset the pcm?

 

Cleared the codes, disconnect negative cable, key in start position for 30 secs. Found the NTKs at O'Reiley PN#24151/ 23506

 

NGK and NTK are pretty much the same company.

 

Codes were off for 2 days but came back over the weekend. Checked wires and the harness all the way back to every connector and nothing is exposed to short it out. Any suggestions? The CAT is only 2.5 years old. LT 3" Pacesetters into Y pipe, to cat, to SI/DO flowmaster.

 

What codes are you getting?