RichardL is right on the money, with his advice, again! As far as throwing parts at a problem
and hoping they fix it?! That should come out of Ford's/The Tech's pocket and not yours,
as they are basically using your 'Trac and you wallet as "Guniea Pigs"!
BTW, timing chains can stretch, due to heat, and maybe cause the symptoms you are
describing. They get weaker, and more succeptible to stretching over time/mileage
as metal fatigue sets in. Lean codes should be picked up by the OBD ll, which may cause
knock. TPS will usually cause idle/stalling problems. It sounds like your pistons and
valves are not communicating properly to each other. How does this happen, you might
query, on such a sophisticated piece of equipment such as our 'Tracs?;
The OBDll/Powertrain Control Module (PCM) is programmed with a given set of parameters
to refer to in deciding spark,and air/fuel mixtures from the factory, depending on engine temp,
inputs and condition of other sensors in the system, outside air temp/pressure (MAFT /MAP
sensors) and the like. The only thing I can think of that might be causing the problem
you described would be valve/pison timing due to timing chain stretch. As of yet, I have
not seen a sensor that can detect this ( a timing chain auto or wear-tensioner is not
a sensor, if our tracs are so equipped!). The computer has a "Mulligan" thrown at it
that it was not designed to detect. Some may also say, or argue, that if you have a
timing chain wear tensioner, how can you get a knock? This device was designed to
prevent excess timing chain play from causing the timing chain to slip the gear completely
or "skip a tooth", preventing piston-to-valve interference, but you can still have valve-to-piston
timing issues as the chain stretches.
