77AZ

Ok guys 2000 F-150 4x4 with 111k. I noticed the problem driving down the freeway about a month ago, felt like the truck was running out of gas, stuttering, bucking at about 50mph. It threw misfire 6 & 8 codes.

As I plan on keeping the truck a long time I changed the fuel filter, all the plugs (Motorcraft), COP's and fuel injectors on 3 separate weekends testing after each install. Nothing. Problem has gotten much worse and the truck will barely idle now. I cannot get it to throw a code since that first day. I'm not getting an O2 code or else I'd change the oxygen sensors, I just might next for the heck of it.

I'm thinking maybe clogged cat (no bad smell or glowing) or bad crankshaft position sensor maybe? How can I test for this?

Anyone got any suggestions? I am stuck as what to do next. Thanks for any info you may have.

77AZ

Anybody got an opinion?

markymark259

im having the same problem with my 06 f150, just spent 500 bucks to get the fuel pump module replaced and no dice. now they think that its my bent right back tire. but im not sure if that could be the case as the shuddering only happens when i slowly accelerate around 45mph ish

JCR 56

Clean the maf. Use maf cleaner or electronics cleaner, not carb cleaner.

77AZ

Cleaned MAF. No change. I noticed that it will hardly stay running when I put it in D. P and N it still misses but not nearly as bad.

AzNative

Vacuum leak. Gotta be.

77AZ

Re-checked all vacuum lines. All seem to be functioning properly.

I will be hooking it up to a real time diagnostics scan tool. Hopefully that will tell me something. Anyone know where the suggested engine operating values are posted online?

MIKE1982

I just fixed mine this weekend doing the exact same thing, it was throwing #5 cylinder misfire code so i switched #5 coil pak to #2 cylinder, reset the code and drove it until it gave me the service engine light again and it gave me #2 cylinder misfire. So i replaced the coil pak its been running great every since then until today now its giving me the theft light blinking and ont start lol

77AZ

Haha. I think this may be the only time I've ever wished a vehicle WOULD throw a CEL code.

alien85

Check basic stuff, I had the same problem and change my wires and it did the trick,