2001 f150 4.2l v6
 

Hello all

I have a 2001 f150 with a 4.2l v6. it has the dreaded P0171 and p0174 troubles. while checking the vacuum i found the lower intake spacer was leaking and replaced the gaskets between the metal intake and the spacer and the plenum cover as well. I changed the plugs and wires at this time as well. it wouldn't start so i checked the fuel pressure and replaced the fuel filter. then it started but it is smoking terribly. it didn't smoke before I did this repair can anyone think of anything i did wrong that would cause this smoking issue? I am not a mechanic but a fair parts replacer. the motor runs marginly better but still suffers from a very rough idle.

thats the second part of this . I have replaced the crank sensor, the head temp sensor, the isolator bolt gromets, the intake spacer gaskets the plenum gasket. I cleaned the egr ports at this time with carb cleaner and a pick to make sure the sludge was gone. changed the plugs and wires. I purchased the coolant temp sensor. but can not locate it on the engine. i am assuming there isnt one on it at this point. any one have any other suggestions?

Elerikk

Fixed the P0171 & P0174 messages
 

Just wanted to add what I did to resolve these error messages with a CEL on...first off, I have a 2002 F150 with 4.2L V-6 5 speed trans...I drove the truck for 2 years with the CEL on knowing the codes were being thrown. Then about 2 weeks ago my truck starting hesitating, bucking while in any gear and speed. I re-read the codes and a P0156 was a new code added to the other two. So, I changed the drive side aft cat O2 sensor and the problem persisted. So, I finally ordered the upper intake isolation bolts with gaskets and changed them on the upper intake plenum. Since I am a DYI kind of person, I had no way to clear the codes. I drove the truck for 2 more days with it hesitating and bucking and then probably after about 5 - 6 re-starts and driving all over the place my truck starting running like brand-new..! The CEL has now been off since the fix (you have to pull off the neg batt cable) and with confidence the truck drives like new. One thing I learned is all DIY people with just a simple scan tool cannot re-set the trouble codes and the codes hang in memory causing your vehicle to run bad until the old trouble codes are completely cleared out (re-starts). All the while new drive points are being built. I'm sure driving the past 2 years with the P0171/P0174 codes probably did not help the O2 sensors as well. I hope this helps someone..!