Teach your old Chevy new tricks?

[tlillard23]

Trans Juice? Who knows, the shop that rebuilt the trans and i had to visit them 7 times in 3 years isn't on my Christmas card list!! LOL

[tlillard23]

Originally Posted by Stevemo

I suppose I don't know how exactly hill descent works but I know the newer models of vans have it along with the additional gears. If you had access to one to suck the programming out of that would be interesting. To be frank, my 1991 Dodge Roadtrek with the 318 handled down hill grades better than our 2004 Chevy.

@Stevemo I see booster already replied but, You might be mixing up your terms??
Hill descent is for 4x4 operation on slippery slopes, using ABS and gears to keep traction - otherwise the ABS sees wheel lock and just lets go, no brakes (plenty of breaks though!!)

I believe you're referring to the engine braking/trans braking that is coded into the tow haul feature of newer vehicles. (GM calls their system "grade braking") I think you could sort of program that into your tow haul button, but it wouldn't know if you're on a downhill or not and keep the torque converter locked up all the time when coasting. perhaps normal mode would be for flat surfaces and tow all for uphill downhill.
I did a little looking and MAYBE POSSIBLY you can do it, they have a high speed and low speed throttle torque converter activation/ deactivation on Coast. You could possibly toy with those numbers enough to make it relatively usable MAYBE. but you'd have to shut off tow/haul on the freeway, and anytime that you just wanted to let off the gas and coast. but if you're doing that you'd HAVE TO make the "normal mode" equal to tow haul without the grade brake. it'd be tough to do for the limited amount of hills I tow.

[booster]

Originally Posted by tlillard23

@Stevemo I see booster already replied but, You might be mixing up your terms??
Hill descent is for 4x4 operation on slippery slopes, using ABS and gears to keep traction - otherwise the ABS sees wheel lock and just lets go, no brakes (plenty of breaks though!!)

I believe you're referring to the engine braking/trans braking that is coded into the tow haul feature of newer vehicles. (GM calls their system "grade braking") I think you could sort of program that into your tow haul button, but it wouldn't know if you're on a downhill or not and keep the torque converter locked up all the time when coasting. perhaps normal mode would be for flat surfaces and tow all for uphill downhill.
I did a little looking and yes you can do it, they have a high speed and low speed throttle torque converter activation/ deactivation on Coast. You could possibly toy with those numbers enough to make it relatively usable. but you'd have to shut off tow/haul on the freeway, and anytime that you just wanted to let off the gas and coast. but if you're doing that you could just make the "normal mode" equal to tow haul without the grade brake.

Interesting information.


I think there might be one thing to consider concerning backward load on the parts. I ran into this long ago when helping out with a guy having clutch issues on diesel pickup with engine braking option on it. He was towing a huge and heavy trailer in tough hills. He had it chipped to get more torque and clutch could hold all of it fine, but it would slip on downhills if he used the engine braking to the max. We eventually found out that the clutch was rated for considerably less torque in reveres direction and he was also getting higher torque because of the massive weight he was trying to slow down. I was very surprised that the engine brake would generate that much torque but apparently it did.



I have no idea how much a closed throttle open exhaust gas engine can generate, but also no idea of how much torque the converter clutch can handle. I do know that the make two and three disc converter clutches for the 4L80E, so the stock one must not be able to handle a lot past normal engine levels of torque. There may or may not be similar questions about the trans gears and clutches in the reverse direction.

[tlillard23]

As Booster stated, the backwards load on the trans parts might lead to longevity issues, so I am not trying to create an engine brake with software.

OP
Did some more updates to the tow/haul mode with HP tuners. It will now run up to redline (uses torque converter unlocked per factory at WOT, but stays locked at 97%), will downshift at WOT (slightly less % for 4th), but will remain locked at anything below 97% throttle (mostly).

I found out Boosters program was too much to think about while towing, I didn't want to manually downshift every time I needed it, and effectively "manual mode" makes tow/haul mode unusable for wife to drive in the hills.

it's still a compromise - -
Boosters program will allow you to use WOT, TC locked and not downshift, so it becomes basically a manual valve body - but you don't get any torque converter power for towing. (his doesn't tach out to redline, unless manual shift, but that's easily changed). Shortshifts and likely give a little better MPG for certain conditions.

My program reverts to mostly stock characteristics at WOT (with 2nd gear TC lockup), will downshift and will use TC for towing at WOT - but if you watch the %throttle and keep it below 97% TC stays locked. uses all the tach, locks up mostly, possible MPG bump

The factory GM trans/engine controller (w/HPtuners) isn't really set up with enough variables to make the perfect shift points/TC activation etc. We want the least amount of heat, most power and best MPG , it just isn't possible for varied conditions. I drive empty rig to work on a hilly road, and also drive loaded cross country with/without a trailer, and tow 6000lbs regularly. I'd like to have different shift points and TC lock up for each condition, AND make it "push button and drive" easy, for wife/friends to help share driving.

Time for a new rig instead of new tricks!! Let me know when the prices come back down to reality!!!

[tlillard23]

Coincidental affirmation of software shift fiddling:
I had a BMW 128 as a loaner recently, when you put the car in "eco pro" mode, the transmission shifted just like the HPtuned transmission we have been discussing in this thread. In gear you could apply a lot of throttle with the torque converter locked, at close to WOT eventually it'd unlock and downshift or let the tcc slip, but similar feeling as discussed in this thread. I think maybe it validates our tinkering with the shift points.

I did a quick look and all of the online "car guys" posting about what eco pro mode does are mostly wrong, as usual. It just locks the TC early and often for more MPG (and therefore less fuel converted into transmission heat). *converted, very puny lol

[Bangorbob]

I know this is an older post with lots of technical info. I understand some of it. I am trying to keep both engine and trans temps down. The question(s) I have are:

1. Which is the best tune for the average driver
2. Do you have to change any hardware?
3. Is it just software change?
4. How would I install the change?

Thanks a lot for all the info you guys provide.

[booster]

Originally Posted by Bangorbob

I know this is an older post with lots of technical info. I understand some of it. I am trying to keep both engine and trans temps down. The question(s) I have are:

1. Which is the best tune for the average driver
2. Do you have to change any hardware?
3. Is it just software change?
4. How would I install the change?

Thanks a lot for all the info you guys provide.

The best tune will be a lot of personal choice things, I think, and based on how much, if any, manual input you want to do to keep temps down in the difficult conditions. Normal conditions don't need to be changed if don't want to, although I did the change the shiftpoints and lockup to get rid of the manic downshifting all the time on rolling hills. By using the tow/haul button you can have on tune for normal driving and another one for staying cooler in tough conditions as the two modes program totally separately. I count on some manual gear selection on tough climbs to be able to keep in the best rpm range which can be necessary on steep climbs with sharp corners also. In normal driving if it starts to lug on a hill before it is allowed to shift down, I will drop it a gear to get over the top sometimes, but it isn't needed very often with the points I chose. I would call my choices to be a bit more complex than an average driver, but not a lot worse than normal downshifting manually to climb long and steep grades.



You won't have to change any hardware on the van as all the changes are to the PCM software program. You do need to get a compatible tuner, though and have laptop to or PC to alter the stock program you copy out of the PCM. Once done you load it back into the PCM with the tuner, which is a small box that plugs into the OBDII port. You can also hire the tuning done by a shop that does tunes and already has the tuner and knowledge of how to use it, although finding one that understands what you are trying to do might be hard as they do almost all high performance stuff.


As said, all software.


Installing will take 10 minutes most of the time max, same with uploading a copy of the PCM program to use in the first place. Making the changes can be a pretty long learning curve if you aren't familiar with how all the stuff works together in the transmission. The changes are mostly made on the tables you see posted earlier with speeds, load, and TPS position the variables.

[tlillard23]

Agree with booster. all software. will 100% change the thermal issue. factory ABSOLUTELY doesn't lock up the torque converter untill ~50 mph, all heat. *side note, blocking off the pass through air will also help at slow speed. see boosters posts

[Bangorbob]

Ok, I think I ain't too smart but. Do I understand that tow/haul will lock the torque convertor, therefore when running up a long steep grade the trans should run cooler?

[booster]

Originally Posted by Bangorbob

Ok, I think I ain't too smart but. Do I understand that tow/haul will lock the torque convertor, therefore when running up a long steep grade the trans should run cooler?

I think most of us were wrong in our tow/haul assumptions before seeing the actual programming of it has and can have.


Normal and tow haul use identically laid out charts like you saw earlier in the thread so they could be set the same if you wanted.


The factory settings actually had the torque coverter locked less of the time on our van. The raised the shift points to have more hp available to move a heavier van, and left the torque converter unlocked because an unlocked converter has torque multiplication capabilities so can move heavier loads faster. The downside of programming like that it way, way more heat generated and that is the big deal in our 4 speed Chevies. The 2010 and up 6 speeds are locked up almost all the time and don't overheat.


My programming of tow/haul raised the shift points to compensate for lower torque multiplying and lowered the lockup points to be locked in common steep climbing circumstances, based on experience in the mountains in the earlier times with our van.

[Bangorbob]

Thanks Booster. I had my 05c210v reallly heat up when we driving thru Bear Country USA, South Dakota. Had to open all windows and turn the heat on full. To me this was unsat. I would like to be able to load a program such as yours to be able to lower trans/engine temp.

[booster]

Originally Posted by Bangorbob

Thanks Booster. I had my 05c210v reallly heat up when we driving thru Bear Country USA, South Dakota. Had to open all windows and turn the heat on full. To me this was unsat. I would like to be able to load a program such as yours to be able to lower trans/engine temp.

We got pretty hot at Bear Country also as it was before any changes were done.


IIRC, the ride through was very slow moving and probably was nearly all in low gear. Unfortunately, there is no way to have the converter ever lock up in low gear in the programming so you would need more conventional ways of addressing that kind of issues if that is how it was for you. Heater on works, but is uncomfortable for sure, as does dropping it into neutral revving up the engine to move more water and air through the engine and radiator, whenever you get the chance. My guess is that we might well need to run the add on fans we have, but rarely use, in Bear Country. I think there are lots of very warm vehicles there of many types.



Add on fans are a good thing at very low speed like that as there no real airflow except for the main fan. Making sure the OEM fan clutch is good certainly can be a good thing as they do fail sooner or later, ours did. Bigger radiator won't help at low speeds, just delay the inevitable.

[SteveJ]

Another issue causing low speed overheating is having the hot air from the radiator recirculate to the front of the cooling stack. Mitigating this by making sure that the air does not recirculate over the top and sides of the cooling stack will make a huge difference in cooling system performance in low speed and stop and go situations.

[booster]

Originally Posted by SteveJ

Another issue causing low speed overheating is having the hot air from the radiator recirculate to the front of the cooling stack. Mitigating this by making sure that the air does not recirculate over the top and sides of the cooling stack will make a huge difference in cooling system performance in low speed and stop and go situations.

Yep, this is what tlillard was referring to earlier.


I did this a long time ago and it is described in the thread.


I found it did not radically change looping out the sides of the area around the radiator, but there was some. Most of the looping was air that came out from under the van if there was any breeze from the rear.


The bigger benefit for us was in low speed cooling and a lesser benefit at higher speed as sealing the bypasses around the radiator put all the air going into the engine compartment through the radiator instead of around it. The benefit was magnified with the larger radiator we put in so got even better.


Our radiator only cools the engine as the trans is on it's own coolers so engine stays very cool.

[Bangorbob]

What is the cooling stack? I think I understand, but a little help here. If you are referring to anything under the hood and basically past the radiator going to the rear, then I would almost understand.

[SteveJ]

Originally Posted by Bangorbob

What is the cooling stack? I think I understand, but a little help here. If you are referring to anything under the hood and basically past the radiator going to the rear, then I would almost understand.

The cooling stack is everything that radiates heat "stacked" in a row with air being driven through it all. Trans cooler, power steering cooler, A/C condenser, engine radiator, engine oil cooler, charge air cooler as used in some diesels.

[SteveJ]

Originally Posted by booster

Yep, this is what tlillard was referring to earlier.


I did this a long time ago and it is described in the thread.


I found it did not radically change looping out the sides of the area around the radiator, but there was some. Most of the looping was air that came out from under the van if there was any breeze from the rear.


The bigger benefit for us was in low speed cooling and a lesser benefit at higher speed as sealing the bypasses around the radiator put all the air going into the engine compartment through the radiator instead of around it. The benefit was magnified with the larger radiator we put in so got even better.


Our radiator only cools the engine as the trans is on it's own coolers so engine stays very cool.

Not having to do with class B but for our Safari Trek on a Chevy P30 chassis I had to install an air dam on top of the radiator, pipe tubing down the sides of the radiator and then installed chloroplast in the open area in front of the cooling stack on the bottom. This has all performed well for low speed driving/crawling compared to before and improved highway speed cooling significantly. The cooling fan now does not engage nearly as much as it usta. Crawling engine temperatures and A/C performance when crawling have greatly improved.

[booster]

Originally Posted by SteveJ

Not having to do with class B but for our Safari Trek on a Chevy P30 chassis I had to install an air dam on top of the radiator, pipe tubing down the sides of the radiator and then installed chloroplast in the open area in front of the cooling stack on the bottom. This has all performed well for low speed driving/crawling compared to before and improved highway speed cooling significantly. The cooling fan now does not engage nearly as much as it usta. Crawling engine temperatures and A/C performance when crawling have greatly improved.

Yep, as long as you are moving the hot air usually makes it to the sides or rear to exit and not go out and back around. Sitting still with a light wind from behind can be really bad.


Have you even noticed you will run a touch warmer on a very windy day even at highway speeds if it is a full on tailwind. We had over 50mph tailwind for a while once and it was very noticeable on the scangauge, but we can even see it at 25mph wind. A lot probably depends on where the thermostat is. The LS engines have it on radiator to the engine instead of in the hose to radiator like the old engines did.

[SteveJ]

Originally Posted by booster

Yep, as long as you are moving the hot air usually makes it to the sides or rear to exit and not go out and back around. Sitting still with a light wind from behind can be really bad.


Have you even noticed you will run a touch warmer on a very windy day even at highway speeds if it is a full on tailwind. We had over 50mph tailwind for a while once and it was very noticeable on the scangauge, but we can even see it at 25mph wind. A lot probably depends on where the thermostat is. The LS engines have it on radiator to the engine instead of in the hose to radiator like the old engines did.

A strong tail wind does make the cooling fan run noticeably more, especially when the A/C is engaged in the heat.

Our thermostat on the '97 7.4 Vortec is mounted in the traditional spot at the manifold.

[Bangorbob]

So IF I were to install electric fans, would they be push or pull?