6.4 Intermittent Power Limit

a_moore

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Hey guys, i have been away from here for a long time.

My 2008 F250 ZF-6 will cut power going down highway in 4th gear. It is like the cruise just kicked in and you cannot give it any more power. The temps all stay normal. my first thought was throttle position sensor, but its scaled to position based on the H&S display. I could shift to any other gear and back and it works for a bit.

We are running in Overdirve now and there is no problem.

Any help or suggestions are welcome.

The cruise has always been sporadic, works for a few weeks then does not. Could this be related to speed sensors? I have never got the Traction Control Light.
 

a_moore

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It happens in 4th on highway @ 2400rpm and 65mph
It happens in 3rd on highway @ 2400rpm and 50mph

Can hold pedal flat and no change. Thank god for overdrive getting home.

I am guessing either crankshaft/camshaft sensor.

I cannot tow heavy in overdrive in mts until I get this single turbo housing sized more properly for a ZF6.
 

Connor M

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Sounds like it's capping fuel, check for codes. EBP sensor bad and the truck's trying to save the turbo?
 

a_moore

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I may be a total D/A.

When installing the single setup, I ******d the fuel cooler res. I had a 2008 for 8 years, and this is my second one and I did not know it had a seperate pump/system from the engine coolant system.

I am on my second 1200 mile trip towing, I will get out and check tank temp, probably hotter than balls. I assume that I have ruined the HPFP. At least I kept all those parts. I just wanted rid of that stupid half-pipe from low to high, I left the cooler, but tore out the res and re-routed what I thought was engine coolant lines to cooler...I just have a whole lot of NOTHING in the cooler but hot ass fuel.

Maybe I should get back on here!
 

co04cobra

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It didn’t do the hpfp and favors but get the cooler back functioning and take fuel samples for the next several hundred miles.


Or bring it up to my shop sometime soon. You’re do for a visit.
 

a_moore

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Stopped for fuel at 1/8 tank. Bottom of tank ~90F. Truck had not stopped towing since we left SC @ 8:00PM last night...4 hour nap where it idled last night. I see no reason to worry about the res at this point.

Looked at the pile of leftover parts in the bed of Gator inside trailer. The pump is not in the res, i believe to have located it on frame in front of steering box. The lines were full to the top with water so it may have been able to pump and have been functioning just fine. I will add a canister with a vent or re-use the factory one in a different spot.

Rail Pressure fluctuates a great deal, just going to order a new HPFP and install with the up pipes.

And been towing in 4th at 2900 the whole time due to blown bellow in factory up pipes. 10psi 800f cant run overdirve with one head feeding turbine lol
 
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a_moore

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New HPFP from Industrial Inj, New lpfp and filters always changes regular.

The pump was rattling badly and had to be close to letting go. Replaced it and the lp. Noise gone and seems to run better. Had surging pressures and you could hear the pump load and unload. Those are now corrected.

Issue is; take off from a start...first fine, shift to second and it will stall at 2k rpm. When this is happening the rail pressure drops to 750-1,000psi. Then all of a sudden. It will snap out of it and run normal. After this hiccup all others gears normal. Can drive a full tank of fuel at 85moh with no issue between 4th and 5th gears.

I took this video idling at fuel stop today. https://youtu.be/LmBetuAkDDg Pressure surging from 3k-6.5k and loping a little.

What am I missing?
 

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