Transmision and Torque Converter Tuning discussion

[Jackpine]

Originally Posted by cleatus12r

DJ,

How about you use that fancy AE package you have and put it to use!

Here's what you do.

1. Drive in 3rd gear at 45 MPH; no load, not accelerating. Check the Mass Fuel Desired by what the datastream says.

2. Same test...only in 4th gear.


3. Use the MFD data and calculate over time and engine speed.

4. It's not the most accurate, but it may give you an idea.

I have a Genisys sitting here, but it's cold and snowing out.

Yes! that's a good approach Cody! (Your new avatar really creeps me out, you know - how does a guy with the friendly screen names of "cleatus" and a real name of "Cody" come up with such a sinister looking guy)?

Anyway, your approach is clearly the right one. At the "lugging" speed of 45 mph, which gear uses more gas? And, if the tune locked you into the "higher gas use" gear at that constant speed, then it's not the right one.

But, if you are accelerating, and lugging momentarily, do you get out of the high gas use region faster and with less fuel than if you downshift, then upshift again?

- Jack

[cleatus12r]

Originally Posted by JackandJanet

Yes! that's a good approach Cody! (Your new avatar really creeps me out, you know - how does a guy with the friendly screen names of "cleatus" and a real name of "Cody" come up with such a sinister looking guy)?Vigo the Carpathian from Ghostbusters 2

Anyway, your approach is clearly the right one. At the "lugging" speed of 45 mph, which gear uses more gas? And, if the tune locked you into the "higher gas use" gear at that constant speed, then it's not the right one.

But, if you are accelerating, and lugging momentarily, do you get out of the high gas use region faster and with less fuel than if you downshift, then upshift again?Only controlled experimentation will tell. In my position, driveability reins over economy....mostly because people in my neck of the woods USE their trucks.

- Jack

Here's the second part.

[Jackpine]

Thank you Cody. Your explanation of the huge range in A/F ratios for a diesel was a real eye-opener. I had no idea there was such variance. I DID think there was a difference in burn rate though.

And, I knew lean gassers burned hot, which is what is damaging. I did not know that rich diesels burn hot. Yes, I can see that lugging causes a rich mixture, given what you describe. Why the heck does a rich diesel mixture run hot when a rich gas mixture doesn't?

And, isn't "lugging" a "heavy" load for both? Couldn't the A/F ratio for a diesel be adjusted for this condition to keep from being too rich?

I totally resonate with this statement: "Only controlled experimentation will tell. In my position, driveability reins over economy....mostly because people in my neck of the woods USE their trucks." I hope you did not think I was suggesting some kind of tune that made the truck marginal to drive. I certainly do not have that kind of tune in my truck and would not want one.

As I've said in many other posts, I seem to pass all the other RV's and trucks whenever I take my truck and trailer up over the high mountain passes in Colorado.

I still have trouble equating "Vigo" with you!

- Jack

[soutthpaw]

Cody, great explanation.
a simple version is that the throttle in a gasser controls how much air gets into the engine. In a diesel the throttle controls how much fuel gets into the engine.

as for why lean gas engines run hot. the gasoline vapor like water absorbs the heat in the cylinder from the previous combustion cycle much faster than air does think of a water mist spray in front of a fan on a hot day. So a lean engine puts less fuel in the engine and thus absorbs less heat from the cylinders and so the engine runs hotter...

[soutthpaw]

Back on topic, I have not even had a chance to play with my AE or Speed tracer other than to connect it to put in the enhancement code... I need to get gauges in and also reseal the front axle and upgrade the brake caliper pins as they are sticking, new brake pads and fix the ESOF got all the parts sitting on the bench now just need a weekend or two of decent weather to do the work... then I can start playing with the tunes.
One thing I want to change on the shifting is when its on cruise at say 40mph and it goes to accelerate to maintain speed the rpms jump from like 1500 to 2100 then starts to speed up. so i am thinking of just locking up the TC in 3rd gear.
I saw there is a setting for Cruise Control Accel Edit its rate not speed and there is also an accel offset. not sure what that does but i might try changing the rate from 2mph to 1mph and see if that lightens up the throttle response to maintain speed speed and mine says 2mph so I think that means it will allow 2mph drop below set speed before accelerating to maintain speed.. Does anyone know which setting(s) controls how much throttle % it will use initially or maximum to try and maintain the set cruise speed? if i could lower the % of throttle response in the Cruise Control it would probably help reduce the rpm surge and the 3-2 downshifting.....
I love cruise control and use it all the time thats why it annoys me so much when its constantly surging and slowing to stay at the set speed

[Jackpine]

Originally Posted by soutthpaw

I love cruise control and use it all the time thats why it annoys me so much when its constantly surging and slowing to stay at the set speed

Thanks, southpaw, I didn't know a diesel throttle controlled fuel, instead of air. But I knew about additional fuel cooling the engine in a gasser - oh well, I'll try to not take this off topic again.

Regarding cruise control, which I use too. I disliked the way my truck's TC would unlock and lock back up on mild hills to maintain speed too. In fact, quite a while back, I think I started a thread on this.

But, I've found that by reducing ALL the upshift/downshift and TC lock/unlock speeds to the max in the Custom Options menu on my Gryphon, I've just about eliminated this "twitchy" behavior. Now it seems to just add throttle without unlocking the TC under "mild" demand. When the TC DOES unlock on a hill climb, it seems to be a more "natural" thing - the steepness of the hill feels like it demands it. And, there seems to be less "lag" between the speed control reacting to changed conditions than there used to be. Before, there would always be a noticeable dropoff in speed (about 2 mph) before the throttle increased and there was always a pretty big "overrun" at the top of the hill where the speed would increase 3-4 mph above the setting before the throttle would back off.

So, I think you are on to something with your thoughts about the TC and maybe % throttle.

I should add, though, if I'm towing the trailer, I'm right back to the same "overreactive" behavior when the speed control is engaged. The added weight and drag clearly causes a more abrupt/pronounced slowdown and the throttle demand must be pushed over to the point where the TC unlocks.

So, if it were possible, I'd try to move the TC unlock point up higher in the % throttle/speed curve. There really does seem to be enough power available without unlocking the TC so quickly.

- Jack

[soutthpaw]

That's why i have a chip and not a programmer ...6 shift on the fly choices
I see there is a setting for "switch to manually locking converter" its an on or off.. Anyone know how it works? which gears will it lock and unlock and which overrides does it respond to... I am guessing it was put there for a diagnostic aid for tranny problems...

I am waiting on the Fuel sipper tune to try it with cruise and see if it is any different.. most of the other tunes use very similar shift points but are slightly different from the stock points. I would guess there is more difference in the non-PMT1 PCM