Torque Management = Slow Car

[Guardsman]

This is a part information, part request for help/ideas/etc. post.

I got my transmission rebuilt this summer. After the rebuild, which included a basic shift kit (no boost in line pressure, just quicker shifts, etc.), it seemed like my car was running a bit slower, not much much, but it didn't seem like it was as fast as it should have been. My track times proved it (best of 15.85 @ 85 last year in the cold, best of 15.9 @85 this summer, the staging area was reading 135*, but even after temp correction, it wasn't much quicker than before, and I expected to at least see a bigger improvement in trap speeds).

Anyhow, fast forward to about a month ago, I got new 17" wheels, and put 275/40/17s on them, so my tire height dropped by about 1/2", which I figured would only mean the speedo and odometer would be off by just a little bit.

Well, I was wrong. After I put the new wheels on, my gas mileage dropped by about 2 mpg consistently. I thought that seemed excessive, even with the wider tires. So, I hooked up the scanner (Ease) to see what was going on. The results both surprised me, and p***ed me off.

Prior to the tire change, my timing was between 30* and 42* of advance on the freeway at cruising speed, and as I increased throttle towards 30%, the timing pulled back (I posted about that before).

After the tire change, my timing was between 25* and 30* at cruise, and pulled back as I approached 30% throttle.

So, I started looking around at the different parameters, and I noticed one that I had seen on there, but didn't pay much attention to before: Traction Control.

There are two Traction Control readings, Traction Control Requested Torque, and Traction Control Delivered Torque.

Traction Control Requested Torque stayed at 100% all the time, but then I noticed that the Delivered Torque was between 55% and 60% at cruise. So, I did a little experiment, I let off the gas, and I watched the timing, which went up to around 42* (from 30* at cruising speed). I looked at the Delivered Torque. It had increased to 71%.

Then, I increased to 30% throttle, where the advance started pulling back, and sure enough, the Delivered Torque dropped under 55%.

Later, I went digging in my shop manuals for some info on the ABS system, and I ran across some interesting info by accident. I was looking at wiring diagrams for the ABS system, and I noticed, on the ABS module (EBCM to be technical), even on non-traction control cars, there was a Traction Control Requested Torque line coming in from the PCM.

So, I looked a little more, and lo and behold, there was a Traction Control Delivered Torque going back out to the PCM. I read up on the system, and it turns out that the EBCM uses a 0-12V signal out to the PCM on the Delivered Torque line.

So, I am going to see if I can "modify" my Delivered Torque signal the hardware way :D , seeing as how we don't have any way of changing it via software (I have a 99).

If anybody has any ideas, has tried this, etc., etc, let me know. Next week, I'm going to check to verify that the line is there for sure, and if it is, I'm going to verify that it has a signal on it. If it does, I'm going to see if I can splice a regulated 12V signal in to the line, and override the signal from the EBCM. If that works, then I going to set up a switch so that I can change my delivered torque between 100%, 90%, 66%, and whatever the EBCM is putting out.

So.......Let's see what we can find out :D Maybe we can get the genie out of the bottle.

I'm thinking that if my engine is only running at just over 50% power, and even less at WOT, and it's running relatively decent now, it should have some serious get up and go in it at 100% power [img]graemlins/thumbsup.gif[/img] .

[ January 11, 2004: Message edited by: Guardsman ]

[ January 11, 2004: Message edited by: Guardsman ]

[ January 11, 2004: Message edited by: Guardsman ]

[ January 11, 2004: Message edited by: Guardsman ]</p>

[Die Ford V8]

what kind of scanner do yuo have where did you get it how much it cost etc. need to use with computer??

[98Camaro3.8]

<blockquote>quote:</font><hr>Originally posted by Die Ford V8:
what kind of scanner do yuo have where did you get it how much it cost etc. need to use with computer??<hr></blockquote>

He already said the type of scanner. A quick search on yahoo came up with the website: http://www.obd2.com/

[Bird_Of_Prey]

Torque management is one of the first thing deleted in aftermarket programming for LS1's, why shouldn't it work for us? Good research, hopefully Magnus can shed some futher light on this.

[njspder]

is torque management present in both auto's and sticks or jsut the automatic cars?

later
tim

[Guardsman]

Update to that, I read something wrong in my manual, the Traction Control Requested Torque is coming from the EBCM, and the Traction Control Delivered Torque is going from the PCM to the EBCM, telling it that it's wishes were granted.

So, there's no defeating it this way. Only through the PCM.

So, my PCM is f***ing up the whole game. My gas mileage has increased (by about a 1/2 mpg, whoopty-doo), so there must be some learning going on somewhere.

Anyhow, as part of researching this, I ran across a Techlink article (Techlink is the publication for GM service techs), and it said that GM may have reflashes available for different size tires.

So, I checked with my local dealership, and guess what.....not a f***ing thing.

Oh, and one other thing I learned the hard way....the f***ing defroster uses the A/C system as an air drier. I was to alking to a guy who is doing some work on my A/C to facilitate another mod (one that I will elaborate on if and when it's successful, 96-99 guys will be interested :D ), and he mentioned the thing about the A/C being used for the defroster.

I drive several hundred miles a day, and I like to have the fan on low to circulate air, but I don't like it blowing right in my face from the dash vents, so I've been normally driving with it set to go to the defroster and my feet.

So, I turned it off defroster just to see, and lo and behold, my gas mileage improved!!! :mad:

Then I was looking through my service manual, and came across the troubleshooting table for gas mileage complaints, and guess what it said....."Check to see if the defroster is being left on" :mad: :mad: .

It amazes all the time, what we can do with computers.......and the f***idiots at GM can't manage to program the computer to turn the A/C off on the defroster after a certain amount of time?

Oh well......on to solving the problems.

[ January 18, 2004: Message edited by: Guardsman ]</p>