well I took the car to another mechanic, he ran the diagnostic and found the error codes, took out #5 cylinder plug as the code said was wrong, the plug look perfect. The car had new leads and plugs not long ago. He removed the error codes and took a test drive, said everything seemed fine and the diagnostic tool showed zero misfires when driving.
So $65 to diagnose and he says to drive it and if it happens again, go back to him.

So I guess initial panic over but I see the TSB above and this is what mine is doing so lets see what happens going forward.

Thank all.

 

Hmmm. I guess $65 is better than $6500. Ok. I can live with this.

Did you remember to avoid the first guy that claimed the engine was toast?
tom

 

Yup, the first guy no longer exists in my book

 

So I'm slowly working my way through the issue. The truck drives ok so I'm in no real rush (its my second play vehicle if you will.)
New plugs, leads and coil pack have changed nothing, it runs the same and the engine light still comes on. Next up is the Crankshaft Position Sensor basing on the details in the ODBC code sites.
After this I'll be looking at a Vaccuum Gauge test per PawPaw's details earlier in the thread. I guess I'm shying away from this in case the heads need changing.
Stay tuned and as per usual, thanks for the inputs

 

Out of interest, is a Vacuum test or compression test more relevant in this case?

 

A set of heads will probably fix it. These are bad about the valve seat sinking. They can be bought for $175.00 a head remaned. I have used these folks before and had good luck.
FORD RANGER 3.0 LITER V6 REBUILT CYLINDER HEAD 2000 UP

 

Thanks for this. Not sure how difficult it is to change out a head (never done it before). but I guess there's always a first time

 

A compression test will show leakage, but a leakdown test will help determine if the leaks are rings, valves or gasket/cracks. The cylinder is pressurized with air, and then you listen at the intake and exhaust for valve leakage, and through the oil filler for piston ring leakage. Gasket or cracks would show leakage to another cylinder or to the cooling system, leading to bubbles in the radiator more or less.
A vacuum gauge will show valves that don't seat properly, allowing some 'mix' to blow back past intake valves sputtering the base manifold vacuum numbers. The needle on the gauge will flutter when the engine is idling. A steady needle more or less indicates valves are not leaking, and the rpms are enough to develop good vacuum even if there is slight leakage. There are other clues, such as a vacuum reading that slowly drops to zero, or just lower overall, or a reading that starts and stays 'low'.
Cylinder heads require draining the cooling system, removing the intake & exhaust manifolds, the radiator and likely some heater hoses, the fuel line connector(s), the ignition wires & coil(??), the throttle & cruise linkage, and any and all wires to sensors.
Then you get to remove the rocker arm covers, loosen the rocker arms, remove the push rods and put them into a piece of cardboard with holes poked by a Philips so you can put them back from where they came. Loosen and remove the head bolts, and thump the head free of the block. Some coolant will likely dribble into one or more cylinders, and should be removed using a shop rag or paper towel, crank the engine a slight amount, and clean the walls of any more coolant. Heads to the shop, or replacements, while the block gasket surfaces are cleaned, cylinder head, intake gasket, and the intake gasket surfaces are cleaned also. Re-assemble.bye
tom

 

Injector #5 was ignoring all signals and either staying on or staying off or any combination thereof but ostensibly doing its own thing (typical California injector )
Its been at the Ford dealer for a week getting tested etc and this was the final result. Fingers crossed