ford96f150

This is the first time I am posting on here, just found this website tonight and so far it seems great. I was wondering if I could get some help with a problem my truck is having.

For the last 2 weeks my truck has been sputtering and jerking occasionally (usually above 40 mph or coming to a stop). It shut off on me two days ago while pulling up to a stop sign but I was able to get it restarted after about 5 minutes. My belt has also been squealing for the last two monthes all the time, and my check engine light has been on and off for about the last 3 years (unable to figure out a definite as to what was causing that).

I took it into my local ford shop and had them run a dyno and standard oil and filter change (air, fuel, and oil). After talking to them on the phone they said the belt was good (that leaking oil caused it to squeal), that the dyno read codes po420 and po320 (although po320 didn't report twice). That I needed to replace rotor, distributor cap, fluids and some light bulbs. They said that when the test drove it before and after they didn't notice and sputtering. I went ahead and had them complete all of that and when I came in and read invoice and talked to them they also recommended replacing catalytic converter and that other possible causes could be distributor, coil, or PCM.

When I left the shop after about 3 miles it stalled and jerked again as well as one other time on drive home (10 miles). The belt continued to squeak, stopped for most of the drive, then continued again. I called ford but their shop had just shut down for the night.

I wondering if anyone has any information or advice as to what to do next. If I need to replace the catalytic converter I will, but I don't know if this is a typical symptom (stalling, jerking, shutting off) of that or something else? My o2 sensors have been on and off for years (code po420 came up about 1 year ago, but small shop wasn't able to say 100% what was causing it.) If I have been having that code for over a year wouldn't the truck have died before this if it was caused by the converter? What should be my starting point of what to fix or do next?

I am sorry this is so long. I have tried researching what I can, but I don't have much mechanical skills or understanding. I would appreciate any advice anyone can offer me. Thank you.

ymeski56

What octane do you use? Are you in an ethanol state? what Engine?

dr_bowtie

jerking can be caused by many things...2 that stand out are MAP sensor and fuel...

A bad ignition module will do this too...map sensor would throw a code I would think but I have seen times where it didnt...

you need to make sure all parts of the ignition system are good...plugs, wires, cap and rotor...letting these go will put a greater load on teh module and burn it up...

there are 3 things to have tested...fuel pressure idle and load, Ignition Module and MAP sensor...

Also a bad Speed Sensor in the rear end will cause this as well...if it jerks non-consistently I would check this 1st...

ymeski56

Very possibly a Cat back pressure condition. Fits the symptoms. Error code #420 (Cat on 9th of 9 lives) Not expected to land on it's feet this time! Start w/ that, you might get lucky and the #320 might go away. If not, my guess on that would be TFI module. I don't now if you have one or two Cats. If you have two, switch to the single large one, In California it is allowed on F-series vehicles so it should be ok everywhere else. Make sure the pipe size increases at the Y.

dr_bowtie

to check the cat just pull the O2 sensor and put a pressure guage in the hole...just use a fitting and adapt it down to a 1/8in compression fitting...put about 6 inches of metal 1/8in brake line and then the rubber hose to the pressure gauge....then take it for a spin...the gauge should NEVER have more than 3psi...

ymeski56

That's pretty cool. I usually recommend removing the sensor temporarily when the condition presents itself to see if that relieves the problem, but your method would determine the problem before it became so drastically symptomatic.