Alright guys I'm back at this puzzler problem again. Turns out the Stratus I bought from the dealer only lasted me 2 weeks then the tranny blew so I'm back at square one here trying to fix my D to drive again. Basically it's still getting low gas mileage. Here's what I replaced, both O2 sensors from the dealer, new cap, roter, plugs, wires, air filter, entire exhaust system, PCM, and it just had got all new top end gaskets. Driving it one day and all of a sudden notice the gas light came on only after driving 40 miles on the highway right after I filled the tank up half way. So I checked the MPGs on the overhead console, it's showing me 4MPG (I know it's not right but it always used to say 20, now it's saying 4 so it's not lying, there is a problem) I installed a new coil and got about 1-2 MPGs more out of it but it's still low. I unplugged all my fuel calculating sensors (both 02, MAP, CTS, TPS) trying to force it into open loop and using the PCM to use it's preset fuel trims for me because before running with a bad upstream O2 sensor in open loop usually got me 17-18 MPG on the highway.
Now here's the confusing part, I plugged in a scantool, it's throwing the code P0171 system too lean bank 1 (this code came up at the exact same timemy MPGs dropped), says it's running in open loop and it's telling me my fuel trim is 38.2% on fuel system 1, it's sometimes detecting a fuel system 3 which has a fuel trim is -7.8% but that's probably nothing since I don't even believe fuel system 3 even exists. The scantool also tells me my coolant temp is 178 degrees, my long term fuel trim on system 1 is 26.6%, system 3 is -13.3%, and my intake manifold absolute pressure is 49kPa. If any of that information helps at all.

So I'm just confused as to why when running in open loop at idle it will give me a fuel trim of 38%. Is there anything else it pulls data from to calculate fuel mixture? I was thinking maybe the TPS is whacky and telling it the throttle is open so it's dumping fuel, just an idea.

I noticed an insane amount of soot coming out of the tailpipe, I mean like this much:


That first picture isn't nearly as bad as it usually is, I just clean off the driveway a lot, but the second one...well how it gets on the bumper beats me, there's a black trail down my street, there is a TON of soot pouring out of the exhaust which means it's burning most of the fuel dumped into it, there's still an unburnt fuel smell though. I was thinking leaky injectors, but it hold good fuel pressure for a long time and if the PCM is telling me a 38% fuel trim at idle, then it's prolonging the injector pulse.

So at this point I'm completly out of ideas and up for any and all advice, tips, whatever. I just need something back on the road to drive ASAP so I can get to work everyday. Hopefully someone can get this figured out, or tell me if a way to trick the PCM into keeping my fuel trim much lower since it obviously doesn't need half the fuel it's dumping in.

 

What about the air temp (charge) sensor in the intake?

 

Ah yes that's the one I forgot to mention, I also unpluged that too along with the rest, when that's unplugged it throws a code. I've already replaced so much stuff I want to be sure now of what the problem is before I buy more stuff I don't need, I already dumped over $2000 in stuff I didn't need in it so I'm out of funds.

 

I think it's either a bad O2 or charge sensor personally.

 

Sounds like a start, I'll check all the O2 wires for shorts and resistance, get that air intake sensor replaced, and report back.