2004.5 - Power Drops off at 50% Throttle or more

[daniels]

Hello Gentlemen:

Truck is all stock.

It's not throwing an error code.

The whole motor just "drops off" at or above 50% throttle.

It doesn't matter if you roll it on, or stab it, it does the same thing: drops off.

It's like it completely "gives up".

Under 50% throttle it runs normal.

Wierd.

Any ideas?

 

[HOBrian]

Lift pump original??? Any mods ??

 

[jelag]

My 05 acted the same with a restricted fuel filter...

An I agree with HOBrian if you have an engine mounted pump...

 

[AH64ID]

Sounds like a fuel supply issue like the other guys have said. Either a bad LP or a clogged fuel filter. Neither would throw codes.

 

[Turbo_Bob]

No, it sounds to me like a boost coupling hose slipped off or torn. Very little boost.

 

[daniels]

BOB WAS THE CLOSEST IN HIS "ONLINE DIAGNOSIS" - IMPRESSIVE BOB!!
Just had it fixed:
The air filter actually tore and sucked into the housing (<--weird how that happened because the filter is only 12k miles old!) and they changed the Fuel/Water Separator while they were at it. So Bob's "Cummins Aptitude" was on the right track, it was effectively an air intake restriction issue that effected the boost, NOT a fuel issue. I actually wished I would not have panicked and took it in to the shop like that. I could have fixed those issues myself, but since it wasn't throwing a code I was very concerned. Lesson Learned: Check out all the BASICS yourself before you pull your wallet out.

High Five Bob... you get a Gold Star for the day - Jake

 

[AH64ID]

No, it sounds to me like a boost coupling hose slipped off or torn. Very little boost.

Where did you find out about low boost? But I still would have leaned towards fuel as a boost issue with that little power should throw a code. . only boost issues that maintain above about 22-23 psi will not throw codes for under boosting.



Good job, BTW!

BOB WAS THE CLOSEST IN HIS "ONLINE DIAGNOSIS" - IMPRESSIVE BOB!!

Just had it fixed:

The air filter actually tore and sucked into the housing (<--weird how that happened because the filter is only 12k miles old!) and they changed the Fuel/Water Separator while they were at it. So Bob's "Cummins Aptitude" was on the right track, it was effectively an air intake restriction issue that effected the boost, NOT a fuel issue. I actually wished I would not have panicked and took it in to the shop like that. I could have fixed those issues myself, but since it wasn't throwing a code I was very concerned. Lesson Learned: Check out all the BASICS yourself before you pull your wallet out.



High Five Bob... you get a Gold Star for the day - Jake

Glad its fixed!

 

[Turbo_Bob]

Thanks guys. Myself and my dad has experienced this same thing. My dad's 96 while towing, high boost, the rubber intake coupling partially slipped off past the bead. And my turbo VW bug (see below in signature), I was giving a friend a ride, and in high boost the silicone coupling lifted off, I have since changed the clamp, fixed now. When a turbo engine looses boost, it is dramatic power loss.

I thought about an airfilter problem, but I thought that would throw a code and show up on the filter reminder. In your case, it was sucked down the tube, past the sensor in the airbox, extremely unusual in your case. Never heard of a airfilter getting sucked down the pipe like yours. That's why there was no code.

I use an AFE filter, I clean it every 15K, and it catches allot of black soot and dirt within that time frame.

 

[JJPage]

Where did you find out about low boost?



I smell a rat... .