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bill, dodge master tech
Category: Dodge
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Experience:  25 years with dodge drivability and electrical expert
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I have a 2001 dodge Dakota QC with the 4.7. I got a P0171

Customer Question

I have a 2001 dodge Dakota QC with the 4.7. I got a P0171 code and now my truck runs like crap. It has no power when I jump on the gas. And when it takes off its very jumpy. It also is starting to stall when I first start it.
Now to give you a little history, I got a P0420 code months ago and my truck would buck when my truck went into overdrive. But when I took the truck out of overdrive it ran fine. I searched all the dodge forums and a lot of people said it was my solenoid pack in the tranny. I got confused as to why I didn't get a code for that. To make a long story short I basically did nothing and drive the truck like that for months. I couldn't afford to change the cats, btw this is a CA emissions truck. It has 3 cats. And I didn't want to change the solenoid packs either and risk these not being the problem. Can you help me z
Submitted: 2 years ago.
Category: Dodge
Expert:  bill replied 2 years ago.

the p0420 means the cats are junk and could easily be causing the "rls" especially if they (or just 1) are beginning to clog, the p0171 is bank 1 system lean bank 1 is on the DRIVERS side which can also cause the truck to run poorly, a lean code can be caused by a clogged cat OR a vacuum leak at the drivers side OR if you used a BOSCH or any universal o2 sensor, for some reason BOSCH sensors throw codes and never work properly the OEM manufacturer for our o2 sensors is NGK and they work ok.

to see if the cats are clogging remove and set aside the o2 sensors ABOVE the cat this will allow the exhaust a clear (but loud) path to escape if the truck now runs ok the exhaust is clogged and the cats need replacing.

other causes of a lean code is low fuel pressure (55 psi UNDER ALL LOADS, that means you may need to drive the truck under a load with a fuel pressure gauge safely secured where you can read it)

Customer: replied 2 years ago.
why does the truck only buck when it's in OD? Also could my problem be a MAP issue or would I have gotten a code for that
Expert:  bill replied 2 years ago.

overdrive has the highest load on the engine so if anything fuel related is weak well that's where it will show up, when were the spark plugs last changed?

due every 30k on this engine and absolutely NOTHING but the oem NGK or champ's COPPER CORE that came out, when is the p0171 setting? does it set right away or after a drive, bucking is rarely a trans problem UNLESS it is shifting in and out of overdrive, do you have a good scan tool? you will need one to see what is going on, with a p0420 the firt thing is eliminate any clogged or partially clogged cats GOTTA start with the obvious and you stated the engine computer is throwing cat codes ad a lean code you need to resolve these FIRST then see how the truck runs, it's how a proper diagnosis is started.

map sensors are super rare modern sensors last a while and the last map that I had fail was on a hemi some years ago, o2 sensors yup they have a life span of 100k and universal ones don't work, bosch are junk lately with sensors I head to NAPA or OEM too many times chasing my tail on a cheap part, crank sensors fail too BUT WILL set a code, OBD2 rules state every part that can effect emissions HAS to be monitored for 1) being properly installed, and 2) working properly so we now have literally hundreds of codes that can set

Customer: replied 2 years ago.
I've had the truck only 5 months so i can't say when the plugs have been changed. I'm going to do it today. What plug do you highly recommend? I agree on fixing the obvious which is addressing the 420 code. That's the original one and it keeps coming back each time I reset it. The 721 code just came on after the truck started running rough and stalling. I installed a battery shutoff so when I reconnected the battery yesterday the codes reset. I have a basic scan tool not the best.
I want to try what you said earlier to pinpoint a cat problem. Since its Bank 1, can I just remove that pre cat O2 sensor and drive it to see if it runs better? Also can I drive it that way?
Expert:  bill replied 2 years ago.

the exact plug that came from the factory SHOULD BE CAMPION RCMCC4 don't bother with platinum or any other plug they never work right and usually cause misfires.

as for the o2 sure pull the drivers upstream o2 and see how she runs but since these are cats that come as a package of all 3 (from the factory that is ) you get all 3 general rule is if one is dead the others can't be far behind

a decent scan tool from OTC on amaon is around 2 bills but you do need to know what the data you are seeing means

Customer: replied 2 years ago.
I'm going to replace the exhaust myself. Since the two front cats are the only ones with O2 sensors, can I legally eliminate the third rear one. I live in NJ. It seems stupid to have the third one
Expert:  bill replied 2 years ago.

the third one is for NOX the 2 upper ones are for CO and HC my state of CT we are a California emissions state and the fine is huge to remove the third cat, I don't know about your state but if you have adopted California emissions and have an inspection they will catch it and either fine you and fail the truck or fail the truck and not report it up to the inspector, we are watched on the inspection lanes (all independent shops with cameras linked to dmv) and they randomly send rigged vehicles to test and see who is cheating

Expert:  bill replied 2 years ago.

btw since your truck is a cali emissions truck you need to use cali emissions cats or you will throw codes for bad cats still, cali emissions programming is much stricter than federal and NO once a vehicle is built to cali spec it cannot be downgraded that's a federal mandate, and 99% of vehicles built now are California emissions anyway

Customer: replied 2 years ago.
Lol. You just answered my next question which was can I convert my truck from CA emissions.
Can you tell me a place where I can buy CA emission Cats cheap? My exhaust is perfect still so if I can just cut out the cats and replace just those it would save me a ton of money.
Expert:  bill replied 2 years ago.

I would try NAPA or anyone that sells WALKER exhaust parts the OEM number is ***** and NAPA can cross that over, but they don't show a cat to fit your truck in MY area your store will very likely have a huge catalog and can get one and rock auto shows one as well here is a link to them, they are out there but may take a bit of research on you part

Expert:  bill replied 2 years ago.

following up to see if you still need assistance, if all is good please rate the service, rating positive gives me credit for the question and allows me to be paid for it, it also allows me to assist further with this question if needed