breezinintime

I have a 2001 F-150 4.2l v6 single cab stepside 4x4. the truck has 172k on it. ive been having a problem with it hesitating off the line and also feels like its misfiring when at cruising speed running around 2200rpm. check engine light comes on a keeps saying different cylinder misfires. also sometime says too lean bank 1 or 2. ran all kinds of injector cleaners on it. had the injectors prfessionaly cleaned. complete tune up done twice. new cats on it 30k ago. even put a new coil pack on it. it also does it worse when its cold. very raely it will also hardly even drive until it has completely warmed up. it will drive like a couple cylinders are not firing at all. when this happens, it has no power and it i try to gun it, it will knock under the hood like crazy. other days it will drive like its brand new. most of the time it will just "skip beats" while cruising or while getting up to speed. when i gun it on these days, its got all the power i should have. any suggestions?

ymeski56

How many miles on the O2's. As they age their signal switch rate slows and sampleing air has to filter thru contaminant deposit buildup effects reading accuracy.So the PCM ajusts based on non current, inaccurate conditions. Kinda like after the cow got out of the barn & actually it was the goat. Undetonated fuel from cylinders not fired should be producing an over rich condition for the O2's. Miles +30k more likely. Removing them, douche the probe head ventings w/ Electronic Contact Cleaner and see if it has a positive effect. Reduced flow rate through EGR Valve from contaminant buildup or vac leak of actuator diaphragm & habitual use of controlled ignition fuel octanes (89 and above) expedite the demise of O2's & Cat.'s and artificially increase the rate of compression while reducing the amount of cylinder c.i. displacement. Also there's the possibility that there's a poor quality to ground in circuit for the Fuel Injection which would explain the O2's reporting Lean rather than rich. Loss of fuel would result a lean state reading, loss of ign. spark should result in over rich.

breezinintime

that was my next stop. ill do what i can to clean the o2 sensors and get back to you. i just didnt want to replace $200 in o2 sensors. so ill try cleaning and see what happens. i know they havent been replaced in over 50k

ymeski56

Check yer messages