AWD Dyno Runs......43 miles on the SS

[Dyno Dan]

Well, here are the official AWD baseline dyno runs. It's bone stock, and it now has 43 miles on the odometer.

The Traction Control and StabiliTrac were disabled via the button on the shifter. It appears that StabiliTrac is still doing something in the background until the note pops up " Service StabiliTrac", at which point the "ABS" and "Brake" lights come on, and then you can make a dyno run. Since the dyno drums are not mechanically linked, the rear wheels start to move, and then the front wheels decide to play catch up. Even at speed, light load / minimal throttle, there is a speed differential between the front axle and the rear axle, and this also happens at WOT. I'm not sure how much power can be sent to the front axle via the Torsen 3 differential, but on a "non-linked" AWD dyno system the speed differential is about 2-to-1 (rear axle at 125 mph, front axle at 65 mph). Luckily on our 424xLC dyno uses dual PAU's to eliminate speed differentials between axle 1 and 2.

Also, have others seen an AFR trend like this? This SEEMS waaaaaay too rich, I mean I know it's a stock PCM calibration, but did Chevy command 10.1:1 AFR at high loads? Our software flatlines, or bottoms out at 10.1 AFR, so perhaps it was actually richer.

http://f10.putfile.com/thumb/8/21418550230.jpg (http://putfile.com/pic.php?pic=main/8/21418550230.jpg&s=f10)

[Dyno Dan]

Pic on the Dynojet 424xLC with dual PAU's (eddy current brakes / load cells)


http://f10.putfile.com/thumb/8/21510010844.jpg (http://putfile.com/pic.php?pic=main/8/21510010844.jpg&s=f10)

[smokinss]

so what was the result since i can't make the graph bigger to read.

[bbradyc5]

so what was the result since i can't make the graph bigger to read.

275hp
306tq

ugghhhh!

[GTPprix]

He hit the speed limiter, no other reason I can see to shut the run down at 5250 ;)

[smokinss]

when does the limiter kick in. on the way home from the dealer i had it up to almost 130

[Dyno Dan]

You can click on that graph and it should "blow up".

Remember guys, this thing is GREEN, I mean it came home from the dealership, 3 or 4 WOT blasts, and then straight on the dyno. I was suprised by the AFR trend, it's super fat! I didn't get a chance to remove the wideband sensor from the pump (pump sucks from the tailpipe) and move it to a weld bung pre-cat to validate the values. By the looks of the graph, and from previous experience, I would say the AFR is legitimate, and that's it's costing about 12-16 rwhp.

Yes, I certainly did hit the speed limiter. Once I can get my hands on some PCM / TCM calibration software, I'll force a more "dyno friend" strategy.

[Trailblazer1]

the driveline losses on this thing must be amazing...I know mine with awd, while it is fast on the upper end, off the line it, well let's just say I thought it would be quicker. Apparently the transfer case must be sucking up alot of power. With the overrich condition at wot at the big end doesn't that kind of aleviate your concerns about running too lean with a better cold air intake?

[BlaSSer]

Not bad, looks like if it reved out it should hit 300hp.

Chris,
Isn't 12.5:1 - 12.8:1 where the ideal A/F ratio should be? What are you seeing after your tune?

That explains such a big hp gain with just a tune in these things. 10.1:1, ouch, I guess they are really tamed down from the factory. That's where my gas mileage is hiding.

Dan,
Get that limiter out of the way and re-run it. Would like to see if its got 300 in her stock.

[Dyno Dan]

Yeah, I'm working on acquiring a piece of hardware that will allow me to flash the ECM / TCM (I have the software). Accoring to what I'm seeing in the factory calibration, it looks like that while in PE mode, and assuming no COT fueling, the commanded AFR is between 12.2 and 12.8.

According to a trusted source, there is indeed a "Green Engine" break in strategy in the ECM that fattens it up ACROSS the spectrum. I'm not sure when this will expire, but I'll have a Wide Band Commander installed soon, so I should be able to keep an eye on the fueling.

The only other concern I have while running on a "non-linked" AWD dyno in "inertia only mode", is the way this thing delivers power. The rear wheels were spinning at 126 mph, while the front was at 65 mph. I know the differential is a Torsen III, but I'm not sure on how robust it is, or if continuing to run it on the dyno is a good idea. Here are some details on the Torsen unit:

http://en.wikipedia.org/wiki/Torsen

[Dyno Dan]

BTW - anyone have a PCM pinout they can share with me? I'd like to install a Wide Band Commander this weekend, so I need some detail on where to grab the TPS and RPM signal, and then dig up a decent power and ground.

email:
dwh@dynojet.com

Thanks!!

[JohnnyZ28]

That's great information! However, I have no idea where the signal wires may be hiding. :crazy:

Seems like the truck would have peaked above 300hp if you could have wound it out. :yes:

[BlaSSer]

BTW - anyone have a PCM pinout they can share with me? I'd like to install a Wide Band Commander this weekend, so I need some detail on where to grab the TPS and RPM signal, and then dig up a decent power and ground.

email:
dwh@dynojet.com

Thanks!!

I'd like to see a pinout too! hanchettcraig@hotmail.com

[Obsessed]

One other thing that was probably not helping was having the traction control and stabilitrac returning to cause problems. There is a fuse under the hood that you can pull, it's a big yellow one I believe, that will disable them both permanantly for the dyno. I'll see if I can get the pic that someone else posted that points to it.

[JohnnyZ28]

Here is the fuse that needs to be pulled.

http://web.mac.com/bsailor/iWeb/Trailblazer%20Build%20Up/Project%20SS%20Trailblazer/70415589-BCD4-490C-8DD9-27DF912DE491_files/pullfuse.jpg

[Obsessed]

What would happen if you just pulled that fuse out and left it out to drive around?

[JohnnyZ28]

What would happen if you just pulled that fuse out and left it out to drive around?

Then you'd most likely lose the Stablitrak and Traction control... not to mention the ABS ties into that stuff as well.

There would be no benefit in removing the fuse as you can shut those off while driving. I guess, you would get the 3oz worth of weight savings... :D