I had a new cat converter put on two months ago. Two weeks after it was installed I replaced the O2 sensor. The truck seemed to run fine until now. I took it back to the shop and they had to replace the converter already!

I am going to DEQ to get a read out of my emissions. Are there any other signs I can look for to tell if the air fuel mixture is off? There are no CEL codes (at least the light isnt on and it does work)

Its a 1990 Dak LE 3.9L V6 Automatic Transmission w/ 134,000 miles

if your running rich, you will burn out your cat fast. is your exhaust pipe covered in black soot on the inside?

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05 dodge ram daytona RCSB 4x4 hemi #5212
99 dakota 4x4 318 - sold
88 dakota 2wd 3.9
90 dakota 2wd 3.9 rcsb 5speed
93 jeep grand cherokee 4x4

here's one thing..
a friend of mine has a 85-ish ram w/ 318 and 2bbl carb. the gas tank evaporation canister thing is (was) connected to the carb by vac lines, and its supposed to suck in gas vapors. the canister is full of tiny charcoal pellets. anyway the canister ruptured and the carb sucked in a massive amount of charcoal pellets while he was driving down the road, and the engine passed them into the cat. the motor started bogging and running rough and then died. it restarted a couple of times and then died for good. towed home.

the charcoal completely stopped up the cat and it had to be replaced. with cat attached it would not start - period. with cat disconnected it would start and rev, but would not idle.

carb was slap full of charcoal pellets. i took it apart and soaked in carb cleaner and blew out w/ air and it was reborn.

very rich fuel mix can mess them up.
any kind of additives or improper fuel (diesel) might mess them up.
excessive oil burning (plenum) might do it.

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01 1500 Reg Cab 4wd 5.2 auto 3.55 285/75/16 nasta step bar tow hook hypertech 180 3923 trans cooler/filter posi-lok powertrax noslip timbren brite-box pioneer head rockford amp/speaker cobra cb firestick hughes plenum water pump timing chain oil pump rear seal cracked dash

looked in the throttle body and it looked clean. There is a slight rough idle but its always been there. I did find something that looks fishy however. I just have no idea what it is.




I dont know what that sensor is with all the vacuum lines plugged in. But why is that screw in there?

Also: here is a better shot as to its location plus a two pin connector that I cannot find the other end for.



any ideas on how I can test my air fuel mixture? What would cause it to run rich?