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Q: loosing power while driving on 2008 Ford F-350 Super Duty

Thruck runs fine for a while and then starts to lose power, especially on inclining roads. Can't get it over 60mph, even if I floor the accelarator. Sometimes, I pull over and turn engine off and back on and starts to run ok for a while and then loses power again. It never stops or dies, just runs like it is struggling.
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That engine has got to have a check engine light on with that performance issue. And i'm sure it probably indicates it's going into regen ("Exhaust Cleaning") for a crazy long period of time...

My first thought is regarding the high pressure fuel pump wiring harness grounding off the pump body. This was fairly common early on with this engine. There are a ton of other reasons you could have a problem. I assume you have had regular service performed? The engine oil must be changed religiously on this vehicle. Every time it does an "Exhaust Cleaning" Diesel Particulate Filter (DPF) regeneration cycle, it will dump some Diesel fuel into the engine crankcase. After a couple of these regens, the engine oil level will be too high and performance will suffer (along with component durability). I cannot impress upon you enough to make sure the oil is changed religiously every 200 engine hours (or before...).

I agree with b-glaste about having the truck checked at the dealer if it's under 5/100. But I do caution you that you really need to make sure your maintenance is 100% and that there is no performance modifications, etc, that your truck has, or you could have a warranty coverage problem anyway.

And the rest of the advice about the harness and such I mentioned - those repairs are definitely for an experienced technician to handle. It's good to be informed, however.
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This engine and computer controls are very complex. A diagnostic by a qualified technician is wise. Is the check engine light on? We have seen the diesel oxidation catalyst temperature sensors, EGR temp sensors and high pressure fuel pump pressure control solenoid circuit issues. This vehicle has a 5 year/ 100k mile warranty on the engine, it is best to bring it to a Ford dealer.
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