Did you reset the computer after replacing the sensors? I'm not talking taking the battery cable off the post and back on I'm talking resetting the PCM.

In case you didn't to help further more in order for it to work right away you need to reset the computer because it's still thinking to get weird signals from the old sensor. To reset the computer do the following...

1. Take the Negative cable off the battery post and move clear out of the way
2. Turn the headlights on and turn the key to the START position fully forward
3. Hold it there for 30 seconds
4. Let go, remove the key, turn the headlights off, and replace the Negative battery
5. Start the engine and let it sit idle for 15 seconds
6. Turn the engine off and then once you restart the engine next time your PCM will be successfully reset

 

Thanks for the post on this topic. I am having the same problem with the stumbling and back fire when the engine is cold, my engine light comes on periodically.

Why is it everything you do on this vehicle you have to reset the PCM. My speedo and cruise didnt work for two years(was told it was the speed sensor,which is on the trans.,WRONG) It was the rear-wheel ABS sensor on the rear diff that was bad. Long story short after replacing I had to reset the computer on that.

 

Get either a scanner tool or get it checked and let us know what that code is. We can help you further and it helps a great amount to know what the cause of the problem is to diagnose it better since it is over the Internet.

As for having to reset the computer, it's a simple complex answer. Basically the computer is smarter than you think and learns your driving habits and learns how the engine is running and compensates for errors it finds. If you're running lean due to a faulty O2 sensor, it will richen it up to compensate for it.

You have to reset the computer when you replace a sensor or do a modification that would affect performance because you want it to go back to the stock set of mind, basically as if it would run perfect as if it just came out of the factory.

 

This is a long shot but does anyone know if there could be something in the transmission oil system hat could be messing it up for me? My D has the tow package and I noticed there is an external oil cooler in front of the radiator, which i'm assuming is for the transmission. Could it be feasible that when the transmission warms up the oil system kicks in but is messed up and causing the surging/ hesitation when shifting gears?

 

not likely, the trans fluid cooler has fluid flowing thru it all the time when the truck is in gear, its not like it is magically shut off when the trans is cold, the fluid must always flow thru it

and now i have to ask if you tried everything we suggested above and WHAT WERE THE RESULTS?!?!?!???????

 

Well no that is not a likely cause seeing as you state there is backfire when it bucks and hesitates so there is clearly a stoichiomeric (aka air/fuel ratio) issue. Also, the system uses the transmission oil cooler at all time and not just while the fluid is hot.

It could be an issue with something though and I'd always recommend changing the fluid and filter if ever in doubt. Always use ATF +4 and nothing else as that's the only thing our vehicles like and will cause issues if a universal ATF is used.

 

The CAT is not clogged, i changed thed 02 sensors, tranny has new ATF +4,
the plugs are regular copper truck plugs, there is no check engine light, i changed out both pvc's, and i reset the computer exactly as stated above after every modification.

The symptoms remain the same but the D does run slightly better with the new pre-cat 02 sensor. The D only bucks and hesitates when its warmed up to temp and does it primarily on gear changes. When im accelerating, unless i go easy and let off the gas when the bucking comes on, it'll make a sound thats like a loud "clunk" or backfire and feel like it dropped out of gear or lost complete power. The rev's immediately drop. Although, say I'm driving on the highway in 4th gear, thats when you feel the D constantly hesitate like its losing and regaining power. Its not a huge difference. I dont think you'd be able to tell if you were driving next to me, but when you're in the D you can certainly feel it.

I figured the oil system for the tranny was a long shot but I figured i'd ask. I think im just going to throw in the towl and take it to a shop. I'll prob get raped just in diagnostics but i'm stumped at what the problem could be coming from.

 

maybe i missed it (it happens to me alot more lately than normally) but did you ever get the CEL code pulled(i know widow asked what the code was)? that would probably point you in the right direction

 

Take it to Advance or AutoZone and get that code pulled before you go any further before taking it in. A dealership will cost you $98 diagnostic fee and that $98 does go towards any further repairs but you don't want to pay a dealership to do the repairs. I k languid because I work at a dealership.

Also, you did replace the O2 sensor with a dealership one correct? These trucks hate aftermarket sensors, and I know this because mine did the exact same thing and I replaced it with an Advance Auto Parts O2 sensor I believe it was Bosch and made no difference. I ended up using a dealership part, I believe its Denso, and reset the PCM and was good to go!

 

Denso is making the O2's now for Mopar??????


Anyway, I was going to say I think you need to take it in and have it hooked to a OBD-II to see what is going on.