Truck seems to run ok when it's cold, warmed up I can't get it to run right.

Plugs, wires, rotor, cap air filter were changed a few hundred miles ago.

I used "Autolite Double Platinum" APP25 Spark plug gap .o44 inch

"Belden Edge Premium 8MM wires"

It idles perfect but under load it misses and lacks power. I did change the TFI on the side of the distributor with no change in performance. According to the many searches I did on the TFI I'm getting conflicting information on a bad TFI. Some say it either works or it doesn't, some say it makes the vehicle run rough, some say it runs rough after it gets hot.

On the other hand according to searches this sounds like a PIP sensor inside the distributor or a weak coil. None of which I know how to diagnose.

If I retard the timing a bit it runs much better, no misses but the valves sound terrible under load. If I advance the timing to get rid of the valves that's where it starts to miss real bad. No matter where the timing is set the truck idles perfect.

I started changing the timing by ear, drive a little bit, jump out and adjust the timing and see what happens. I can't seem to find the sweet spot in the timing.

I have good fuel pressure, both in tank pumps, 6 port tank selector, high pressure pump on the rail, fuel filter and fuel pressure regulator are new. I don't have a vacuum gauge but if I pull off the vac hose on the fuel pressure regulator it seems to have good suction on my finger.

What do you guys think?
<hr style="color:#D1D1E1; background-color:#D1D1E1" size="1"> Last edited by sloburban; Today at 12:06 PM. Reason: Spelling

 

Miss under load is usually plug wires, I have seen several cheap sets of wires bad out of the box. Beldens Are some of the better ones though. To check coil output, I pull the coil wire out of the distributor and hold it about 1/4" away from ground while cranking, then move it further away and see how far it will throw a spark. 1/2" or more should be plenty.

 

i don't know if you saw my answer in the other thread, so i will say it here too.
get a set of regular autolite or motorcraft copper core plugs and swap them in. i bet it will purr like a kitten.
no matter what the part store counter monkey tells you, these old fords do not like those fancy plugs.
they like plain old copper core plugs.

 

Ok, I changed the spark plugs back to copper core and I have the same results. Truck runs great for 2-3 minutes then starts the missing and lack of power.

 

when it is not running properly, do you get a check engine light?

 

Was it doing it before you tuned it up? Do you have the old cap rotor and wires still?

 

Unfortunately I don't have the old wires, cap or rotor or I would swap them out to see if there's any change.
I do not get a check engine light at all.
I also cleaned the throttle body and IAC, took the EGR of, cleaned it even though it already looked clean and moved freely.
I unplugged the EGR and it did throw a check engine light.

Thanks for all your help guys!!!!

 

The truck ran fine before and after I gave it a tune up..... I think.....
I'm not sure I ever got this truck running properly yet but it's never run this bad before unless one of my in-tank pumps quit working.
I've changed three in-tank pumps in the front tank and two in the rear. Tanks are clean.
Thankfully I have a dump bed so changing the pumps are a 5 minute job and they've all been swapped out under warranty.

 

sorry, but what i gave is about the limit of my efi gas engine knowledge.

 

Well, thanks for any and all of your help
TJC!

 

Personally I had a failing PIP sensor give very similar symptoms AND it never threw a code. At the time I was not so savvy with Ford EFI systems so it took awhile to finally find and repair the root cause. The blue Lightning in my profile pic was the problematic step-child for 6-8 months. At one point I was ready to torch the darn thing

On the other hand weak spark from a failing coil can do it too. A coil is easier and cheaper to R&R.

 

my experience with failing coils is that they need to get hot before they fail, and that takes 10 -15 + minutes, not 2-3 minutes.

 

Even without a check engine light there could be codes. You can check without a scanner. Oldfuelinjection.com (or something like that) shows you how. What you are describing sure sounds like secondary ignition though. Did you try my coil test?

 

What is secondary ignition?
I did not check the coil yet. As soon as I get an extra hand I'll check that.

I did pull codes a few months ago, I had them written down but misplaced the paper.
If I remember correctly I had EGR code, ground on the computer can't remember the rest.
I'll run another test tomorrow.

 

Secondary ignition is the high voltage stuff. Coil, wires, etc. Primary is the low voltage, module, pip etc. Points and condensor onthe older stuff.