Hi everyone. I bought my durango the other day, a 99 5.9. Ran rough a little but the guy said it had been sitting. Well it smoothed out so took it for a test drive. It sputtered a little after a while so I put it in neutral and shut it off and restarted it while rolling and it took right off.

So I was thinking ok it needs an o2 sensor. Got a good deal or so I thought, so I bought it knowing I was going to be putting a few bucks into it.

Something I missed when looking it over, someone had cut the exhaust pipes right behind the manifolds and ran dual straight pipes with no cat back to glass packs then out the back. No o2 sensors.

It idles rough only sometimes and now sputters and backfires when trying to really give it gas from a stop sign or gassing it when already going 55.

No check engine light coming on. shouldn't it always run this way with no o2 sensors. And what would make someone do this. Can the computer be modded to not need the sensors? I confused. Help

Will try to get some pics up as soon as I figure out how.

 

Our trucks PCM is setup to read a pre and post cat o2 sensors. If they where cut out than common sense would tell me that it would cause something to happen. To the best of my knowlege i do not know of a way to program the PCM to "forget" about the sensors..


If i where you for best results....

1. I would start by replacing the exhuast system to included the pre and post cat 02 sensors back into the system...

2. since it sat for awhile i would do a complete tune-up... plugs(champion copper) wires, cap, rotor etc. also, remember to reset the PCM.

3. i would replace all the fluids and filters (oil, tranny, antifreeze, differnential...ect) and DO NOTHAVE THE TRANNY FLUSHED.. changing the fluld and filter is fine..

hope that helps a little, im sure others will chime in with advise too as the day progresses...

 

Thanks for the reply, I figured a whole new exhaust system would be the way to go. My truck has had a lot done to it by the previous owner, lifted, audio system..... didn't know if their was a reason this exhaust system was set up this way, if the guy was half way through doing something and had it get repossesed or something. A lot of time and money on other things to screw up the exhaust so bad for know reason.

 

 

thats not a bad looking truck you have there... (although i can't stand all black wheels..just MHO) get a good exhuast systen, tune-up and fluids changed and it looks like you will have a pretty sweet running ride

 

as stated the missing o2 sensors would cause the sputtering, get the exhaust repaired and get back to us we can go from there.

 

Fastmann also makes an O2 simulator which is said to work very well, although I have not used it myself. Like said earlier, just re-do the exhaust system and do it right rather than a hack job!

 

I never heard of a o2 simulator but after reading up on it after you mentioned it I think that is what this guy was trying to do. Probably got the right pipe set up just no pre cat sensor or simulator for the post.

 

the o2 simulator is for post cat sensors, not pre cat(at least the ones i have seen)

 

All you have to do for a Upstream O2 sensor is just go to a muffler shop and have them weld a socket for the sensor to spin in and just get a simulator for the Downstream. At least this is how I would get away with fixing your problem without having to re-do the entire exhaust system.