bcost882

I have been trying to figure out what is wrong with my truck for the past couple weeks. I keep getting a P0174(too lean bank 2) and sometimes a P0172(too rich bank 1) and sometimes it will throw a P0301(cyl 1 misfire). I have replaced a couple vacuum lines and it still comes back. When I look at my LTFT for bank 1 it is 0-5ish and bank 2 is 10-17. Then when I push to 2500rpm the bank one goes negative and the bank 2 goes higher positive which makes sense with the codes it is tripping. When driving, it will only rev to 3500 and act like it is misfiring(no flashing CEL), let off the gas and it will shake for a couple seconds and then be fine. There is no rough idle and the only thing I notice is the loss of power at 3500 and CEL.
2002 5.4L 157000miles

dismissed

When that happend to me I tried everything and spent a butt load of money and all mine needed was a tune up plugs and coils 00 f150 5.4l

bcost882

I figured it was coils or fuel pump. the last time I tried to put a guage on it though of course the gauge was broken.

dismissed

Did that fix it?

Marc D

Your codes 172 and 174 are both lean codes not a rich code on the 172. Look for a broken or bad vacuum hose especially at the PCV valve or under the intake manifold. There are about 20 items that will throw that code including the EGR valve or the EGR pressure sensor or the MAF sensor. Also if you have plugged CAT it will restrict the exhaust flow and the O2 sensors will react to the high temp and starve the motor of fuel. This would be a good time to spend $65 to $100 and have a small shop with a computer that can read ALL of your sensors look at it. I've been there and spent $400 replacing parts when it was a $3 piece of hose.

bcost882

Sorry it took so long to get back to you guys. Unfortunately no it was not the pump or coils. I even double checked the codes P0172 - system too rich bank 1, P0174 - system too lean bank 2. I took the truck to the ford dealer to see what they thought and they found a wire that was pulled part way out of the maf. They fixed that and smoke tested the intake and it has been about 2 weeks and it hasen't fixed anything. I pulled up the scanner and as I drive around I watch bank one fuel trim go negative and bank two go positive. I am no longer popping codes since it got warmer out but now the codes will separate at the same rate if I sit at 2000 rpm cruising along bank 1 will be at -13 and bank 2 will be at +13 (Idle they sit at B1 -5 and B2+5). My question is now, Is there a way that the crank position sensor and/or cam position sensor cause the fuel trims to be off. I can't see the timing being off since one side would have to be advanced a tooth and the other retarded a tooth. Plus the truck idles fine but I notice a lack of power as rpm increases.
Any thought are appreciated since I am getting really frustrated with this truck.

mustangrich

Try replacing the dpfe sensor. It did the trick for me.

bcost882

Prior complied with.
I have changed the:
Fuel press reg
fuel pump
checked 02 sensors
changed DPFE(because it was broken)
intake smoke tested(actually replaced because of the coolant passage disintegrating)
rebuilt injectors and swapped sides
plugs and coils


I know the crank position sensor controls spark and cam position controls injection. It is just weird that I have no starting or idling issues if those sensors are the problem. I don't think it runs bad enough though for the chain to be the problem.

mustangrich

I know it sounds stupid but try a new fuel cap on your gas tank. Or see if someone at a shop can pressure test the cap like they do hear in the Dallas area for state inspections. You may have a short somewhere causing the codes and that's when a smart guy with a voltage meter may be able to help.