2002 LB7 Duramax problem

[josh_evans66]

I have an '02 2500-HD Duramax/Allison with 184,000 miles. It runs great and has phenomenal torque but whenever it downshifts it just sits at that rpm and doesn't accelerate at all and even loses speed when towing. Immediately I thought, "slipping tranny" but I took it to a specialist and he seems to think that it has something to do with the fuel system. Its injectors were replaced 4,000 miles ago, or so the stealership said, so I don't think they're the culprit. I changed the fuel filter, tranny fluid/filter, and engine oil/filter. It still has the problem! It's not throwing any codes and still gets a respectable 19mpg average. It does surge at idle every now and then. Any ideas on what the problem maybe??

[Mark Rinker]

Fuel pressure regulator? My '02 just turned over 200K, has a slight idle surge, and is somewhat 'flat' during downshifts with a load behind. Just noticed that yesterday as well.

[josh_evans66]

Fuel pressure regulator? Really? That would make sense. It would require more fuel for higher loads and RPM. Thanks for the reply!

[josh_evans66]

Here's an update to the mystery. I got an engine code the other day going down the road towing a van. I got ahold of a scanner and the code read "Excessive Boost Condition". Does this mean that the problem is in the turbo or wastegate?