One thing to remember is that with over sized tires, your speedo will read under. So you might be going fast enough and just think you aren't accelerating like you want. While bigger tires will slow you down, but even with 33" tires I could still get up to 70 before reaching the end of the ramp (adjusting for the speedo being 10% off or so).

 

OE Bosch

Have Ultragage, other than an occassional SAI code 1414 nothing.

Seems to shift fine.

 

Still cannot figure it out. The D2 is extremely sluggish and strains to go up hills or to accelerate. It feels like you pulling a trailer with a pallet full of bricks in it. Going up hills it shifts into overdrive and barely makes it. On flat services it seems fine and seems to run fine other than this very noticeable reduction in power. Anything else to try before sending over to my mechanic?

 

Broken cat's....or cat converter plugging your exhaust. The symtom of this is losing power just like your saying.

 

Low quality gas and gummed up injectors can cause this too.

No mention so far if you are using name brand top tier premium gas or otherwise...

Have you run Seafoam, BG or Techron cleaner through the fuel system?

 

What your saying sure sounds like that could be it!

1) Is there a way to diagnose this?

2) Would it not give me some codes?

3)Would a muffler shop be able to help?

Finally something I can run with!

 

unbolt the y-pipe.
I would also think a blocked cat would show up with a digital thermometer

 

They can check your exhaust system at a muffler shop...

 

I have run Seafoam through it but it does not help and use 93 Octane. Here is a little more background on the vehicle:

Background:
- I have an Ultragauge and am running NO CODES!
- D2 has 111k miles with an engine that only has 35k on it.
- Has an ARB steel front bumper, rack and slightly oversized tires (I am running 275/65/18 (32.07 diameter) as compared to stock 29s, but I firmly believe this does not account for the significant loss of power
- Seem to shift fine
-New O2 sensors and MAF within past year
- No fuel filter to check

Without anything further I can diagnose myself I think I will go ahead and take to the mechanic and have him do the diagnostic.

 

there is a fuel filter, but integrated into the pump. i'd check pressure on the rail, before messing with filter/pump.
new maf...so, I assume your air filter is too.