My Beast (4x4 Suburban)

[Sporty Modder]

Thankyou for the input guys
Thomasan, I pulled codes, ony one was Egr, replaced that and the code self corrected, chassis dynos are pretty far and few between, as are tech schools. My first choice would be to take it to a local tech school, as they usually have all the equipment needed to dignose an issue like this, and they dont charge alot.

[oil pan 4]

Look what I found lurking in the forgotten dust bin:
2001 Chevy suburban Fuel economy project - Gasbuddy Gas Prices

So its a 2001, thought it was a 90s.
He went from 14mpg to over 20mpg with 0 aero mods.

[Sporty Modder]

I never thought about a magnet being cracked in the dizzy.
My gut istelling me the problem is vacum related though, my vac controled abs light started coming on now/ I hate the abs in this rig. I need to get a vac pump on it, or a puffer.

Oilpan, the goal is 18combined, 20 highway. E fans might go on it if I can find some big enough ones cheap. This truck is used to haul/tow and I dont want to comprimise that.

I have the non vortech engine rated @200 hp 300 ftlb 180,000 original mi O oil consumption.

[2000mc]

yea, they definitely feel like it would just be a simple vacuum leak. seen a number of these with the same symptoms/performance fixed a number of different ways. unfortunately i know guys have also replaced virtually everything and keeps doing it, being left with just a handful of options where you're looking at new OE parts that cost near as much as the vehicle is worth, or trying more used parts that could have the same problem.

[2000mc]

tbi i used to have i never got 100%, but i got it to recover out of the stumble faster by turning up the fuel pressure, helped low end power some too. if you take apart the TB the plate holding the spring for the fuel pressure regulator is on a threaded rod. find a couple nuts the same size as the threaded rod first so if/when the tab on the plate gets tired of bending back and fourth and snaps off you can double nut it to keep it from backing down. i didnt check my fuel pressure while i did it, just gave it a turn and drove it, repeat, until it quit helping to turn it more. dont know what i turned the pressure up to, but didnt hurt the mileage, and made it a little easier to drive

[oil pan 4]

If you want a cheap electric fan that will be close to bolt on, at some point GM decided the duramaxes needed to get better fuel economy and more HP to keep up with ford and cummins so the cheap trick they employed was to switch over to electric, see if you can find one of those.

[2000mc]

Originally Posted by oil pan 4

If you want a cheap electric fan that will be close to bolt on, at some point GM decided the duramaxes needed to get better fuel economy and more HP to keep up with ford and cummins so the cheap trick they employed was to switch over to electric, see if you can find one of those.

the new duramaxes have an electronicly controlled fan clutch

[Sven7]

A belly pan should be easy to make. My parents have a '99 Yukon and I've long wanted to mod it. All you have to do is create a few brackets to drop the mounting points a couple inches below the frame, then bolt a stiff coroplast skinned ladder frame to that, BZP style. You can attach it with, say, six or eight bolts for easy removal.

That should get you 5-8% MPG gain I believe. If you make a boat tail you'd see a lot better and get more looks!

[Sporty Modder]

Sven I was looking @those nice flat framerails thinking a belly pan should be easy, I would love to do aluminum skids but will probably start with coroplast, or abs. 8% gain would be 1 mpg. Currently getting between 12 and 14 mpg.
Need to measure the distance between them.

[oil pan 4]

Originally Posted by 2000mc

the new duramaxes have an electronicly controlled fan clutch

That makes it even easier.