Smothers out....

[jimmy57]

2006 F350 6.0/TqShift with 150K miles. When you take off it loses power without stalling but will drop to 550 RPM if you keep into throttle a little or a lot. Acts like a stopped up exhaust but it has no Catalyst and it does not have stopped up exhaust. Has the up-pipes w/o flex joints ( stainless steel slip joint pipe.....Sinister Diesel???). Fuel pressure is 65 psi and doesn't fall below 62 psi. Inspected both filters anyway but nothing in either.   No codes. Passes KOEO, KOER tests. VRef good, All sensor values good. Has tunes but no difference when returned to stock. Test FICM makes no difference. Charge voltage good (13.87V) with no diode ripple when scoped. FICM never goes below 48V.

Motorcraft reman'd injectors @127K miles. Great idle. Instant hot starts.

 

VGT unplugged no change, has 4 inch exhaust and the VGT is functioning based on very noticeable change in exhaust noise. EBP is normal values. ICP unplugged no change. ICP normal KOEO.  MAF is correct and unplugged no change.

 

Autoenginuity is my access and the only thing I see is that it appears PCM is reducing the power. IPR goes to 60%, IP will get to 2000 psi with desired at 2000 psi, computed torque to 650 N-m, fuel quantity desired to about 50 mm3 and then IPR begins to drop with IP desired and actual falling to 550 psi, IPR 21%, and injected quantity to 9 mm3 (normal in gear idling is 18-19 mm3 on AE for a 6.0). It will run smooth but at 550 RPM. If you release throttle it returns to normal idle with IPR 25-26% and IP at 635-650 psi.

EOT is accurate and isn't over 180F as I don't have to drive it but 100 yards for it to do this.

MAP goes to 22 psi before falling back to atmospheric (14.6)

I have noticed that I can pop it into N and it races up with all the values returning to normal for unloaded and revved 6.0.

 

It just seems like PCM is killing it for some reason.

The slip to neutral and it recovers w/o moving foot on throttle is puzzling but nothing I can see on AE in transmission values looks odd. Trans shifts fine and goes  into gear immediately. No sign of slipping.

Air filter and plumbing is clear.

 

6.0, the gift that keeps on giving......

[lmorris]

Sticky IPR is only thing I can think of. The 60% seems high to me. 

[jimmy57]

That is only briefly if I step into it hard and may have been the number I remember when tested with tune still loaded. The IPR % goes to what I normally see with desired and actual pressures matching and in normal range but then immediately starts dropping as the desired fuel number drops.

 

Throttle number stays in line with amount throttle is depressed.

 

The IMMEDIATE recovery when I move gear lever to N makes me curious of a TCM request for power drop if that exists.

I don't see anything that sticks out as unusual with any transmission PIDs

[Matt Saunoras]

Slightly off topic I had one with a cracked pickup tube that gave me a real run for my money.  It would idle down real low, stall, reluctantly restart and run fine for a little while. 

[jimmy57]

I may pull the pan down and look. This truck has had a LOT of work done to it. It had a rocker arm tip "mushroom" retainer clip break and go through oil pump.

 

The changes in the PIDs that I'm seeing could be totally normal for lack if injected fuel. The correlation between computed torque from CKP sensor may be what causes IPR signal and desired injected fuel quantity to fall. I have never had any reason to watch those same PIDs on a truck with low fuel pressure or plugged fuel filters. The behavior could be the same.

 

 

The truck had a short period of flutter/misfire at highway speed and then it went to the smothers out(loses power?) behavior.

[BrunoWilimek]

Fuel quality or failed fuel pump? Remove secondary fuel filter cap and see if it will refill reservoir. had one with similar issue and pump was faulty and it would only suck enough fuel to run, but not enough to run well.

[jimmy57]

To put this one to bed:

I was right, the PCM was pulling this one down due to programmer.

The guy that owns it used it as a farm fuel and welding truck for the last couple of years and decided to spend some more money. I pulled oil cooler and looked at the screen in case it was getting plugged...it was spotless. I pulled the pan to make sure it was not sucking air as I decided that might be letting it smother down and then unscrewing oil filter cap immediately looking for air was not valid. No pickup tube o ring or upper oil pan seal issues. At that point I was ready to investigate a PCM. FICM swap did nothing.

Since it was going to another shop, recent Ford Master that has his own shop, to get the PCM installed and profiled I unloaded the program. It is fixed! I put program back and it had the problem and removed it again and it again is fine. I removed the program and tested it 2 years back and it did not make a difference.  I really can't remember all the screens and details but obviously it did not take the program, or all the remnants of i, out before. This truck developed the "allergy" to the programmer after it had been on the truck  for 3-4 years and 60K or more miles. I am suspicious of the PCM and now worry that it may yet fail. BUT IT IS RUNNING PERFECTLY NOW!!!!  Owner knows my concerns and will drive it. He took the program out of it 2 years back when he called me one day telling me about and I told him to reset to stock with no change so he is as puzzled as I am. That programmer is going in the trash.