2002 2wd dakota 3.9. same problems. started fue months ago with replacing 2 o2 sensor(bank 1 s 2(down stream),and bank 2 s1(upstream) with aftermarket ones on ebay. it ran like crap after. it turns out dodge dont work well with anything els but mopar. i replaced o2 sensor bank 2 sensor1(upstream) with a mopar part, worked very well for about 2 months. on the way form work it backfireing poping no power(day 1) ran a scan it said running rich bank1, multuple cylender missfire(1,3,5) small vacume leak. so i cleared the codes to see what new codes will appear.(day 2) took the truck for a drive and it happened again same codes but different cylinders(2,4,6) also small vacume leak. i dont think theres alot wrong(im thinking about replacing upstrem (and ebay crap downstream) o2 sensor for bank 1 might solve the problem, sounds like gas/air problem to me. anyone els got any sugestions

 

ntk/ngk are the best o2 sensors for the our trucks. dakotas do not like bosh for some reason.

 

Moving to the correct section.

 

do u thing the o2 sensor is the problem

 

how many miles? I get 1/3/5 on mine but i run a very modified timing map. I am wondering if your (and mine) timing chain has stretched just enough that the sync sensors arent picking up on it, but it's throwing the dizzy & valves off just enough to trip O2's.

 

159 000 kms... About 100 000 miles

 

How are the plugs, cap, rotor, air filter? Pull a plug and check it out. Could be a coil problem too.

Then check for a vacuum leak.

Odds are the multiple misfires are causing the "running rich" codes.

 

Welcome to the forum Rut.

I deleted the duplicate "turnip" thread.

 

New plugs and plugs about20,000 km ago

 

New plugs and wires