First long trip with the 2024 6.6 gas and the faux Allison 10 spd

64BAwagon · March 29

I just got back from and extended trip covering 4000 miles with about 3000 of that towing my fifth wheel.

I scaled the truck the first day out with the trailer loaded for our typical trip. We have a Reflection 337RLS that has a Splendide washer in the front closet. This model is a little pin heavy to begin with and the washer just adds to it. I did not get a split weight since I already know its heavy and I bought the 3500 because of that. I am solidly within my load limit even with all the stuff in the bed. This setup likely would overweigh a 2500. In the bed I had my 4500w inverter gen, a 20lb spare propane cylinder, a 6 ft fiberglass ladder a 6 gallon spare gasoline tank with a pump, 2 crates of red oak firewood and a couple cases of drinking water. All told the trailer and cargo come out to 13,000 over the unladen truck weight. I also had 2 bikes on the back of the trailer but they are light aluminum frame pedal bikes, rack and bikes are less than 100#. The trailer is a mid profile 35 footer.

Having set all that up here is my impression of the new truck with the 10 speed versus my previous 2021 with the 6 speed.

First off the 10 speed is an improvement, not light years ahead, but an improvement none the less. I had no issue with the 6 speed in my 2021. I did lock 6th gear out when towing though. It had a habit of flaring when shifting back from 6 to 5 and I was worried about the long term effects of that. Had I kept it my plan was to replace the torque converter and install a shift kit since the TC is a weak link in the vast majority of the GM transmissions.

When towing I put the truck in "L" and moved the selected gear to "8" which locked out 9th and 10th. I typically run around 65 MPH and this kept me around 2100 RPM which experience has found is where this engine likes to live when towing. I would like to see some sort of retained memory when using the "L" selection. It becomes tedious when every time you get back in the truck you have to reselect the gear. It would seem that GM could retain that info when connected to a trailer but at this point mine doesnt. A small thing but when towing a lot it becomes a small annoyance.

After all the 4000 miles of driving using the trucks fuel economy monitors and well as the ones on my Scangage I came to the conclusion that 8th gear was best suited for this load. I did try using 9th gear a few times which put the truck in the 1700 RPM range but it made no improvement to the mileage either instant or longer term. I even went so far to allow the 9th gear upshift on the longer downgrades and didn't see any advantage. It did raise the trans temp 2 degrees with the additional shifting when selecting 9th. My trans temps were around 145-160 consistently no matter the terrain. The only time I saw 180 was in Florida during an I-4 stop and go session that lasted about an hour. It would seem the trans cooler on this truck is solid. Something else I noted thanks to the SG3 was that the "oil temp" ran higher than I anticipated. I have never been able to monitor oil temp before so I didnt know what to expect. Once the truck was at operating temp the oil temp ran around 215 to 220 degrees. I dont know why but I thought that seemed high. It does offer a solid argument for keeping a high quality oil in it and changing regularly.

I would not tow heavy with this truck without a Scangage. I played with the display several times and have the 3 screens setup for similar base gages with a few varied between screens. I did have an issue with the Scangage not booting up occasionally and I contacted them. When I first got it in December I downloaded the latest program on WIFI but by the time I contacted them in March they had a new update that supposedly corrected this. I did however have an issue yesterday with it not booting up after a remote start sequence. I plan to contact them with that info and will follow up.

My mileage averaged about 8.25 to 8.5 with a couple of stretches of sub 8 and a couple of 9.25-9.5 This setup is very sensitive to head winds and the gasser lacking the diesels torque is most evident when windy. Its not bad but the mileage suffers. Going through Ohio yesterday was pretty windy and depending on the direction brought down my mpg to a little over 8. Once you get North of Dayton its pretty flat and with low or no wind the truck is capable of 9mpg but that rarely happens in Ohio in the spring.

I do have plans for an exhaust mod but I haven't decided between the 3 1/2" Borla muffler or the MBRP kit. The Borla is almost a direct fit with the stock muffler cut out and 2 band clamps but I like the MBRP sound. The price difference is substantial but I dont want to drop $300 on the Borla and then find its too loud. Stay tunes for that one.

Overall I am still pleased with the setup and economy of the gas engine, consider the price of DEF along with the added cost of diesel it doesn't come close to covering the price split. Its hard to argue with the diesel torque though. If I felt the reliability of the Dmax and the DEF weren't an issue I would probably own one but in today world it doesn't add up for me, although I do have a feeler out for info on when the 8.3 comes online. LOL

Hopefully you found this rant useful.

Scott

Edited March 29 by 64BAwagon

Pryme · March 29

14 minutes ago, 64BAwagon said:

I just got back from and extended trip covering 4000 miles with about 3000 of that towing my fifth wheel.

I scaled the truck the first day out with the trailer loaded for our typical trip. We have a Reflection 337RLS that has a Splendide washer in the front closet. This model is a little pin heavy to begin with and the washer just adds to it. I did not get a split weight since I already know its heavy and I bought the 3500 because of that. I am solidly within my load limit even with all the stuff in the bed. This setup likely would overweigh a 2500. In the bed I had my 4500w inverter gen, a 20lb spare propane cylinder, a 6 ft fiberglass ladder a 6 gallon spare gasoline tank with a pump, 2 crates of red oak firewood and a couple cases of drinking water. All told the trailer and cargo come out to 13,000 over the unladen truck weight. I also had 2 bikes on the back of the trailer but they are light aluminum frame pedal bikes, rack and bikes are less than 100#. The trailer is a mid profile 35 footer.

Having set all that up here is my impression of the new truck with the 10 speed versus my previous 2021 with the 6 speed.

First off the 10 speed is an improvement, not light years ahead, but an improvement none the less. I had no issue with the 6 speed in my 2021. I did lock 6th gear out when towing though. It had a habit of flaring when shifting back from 6 to 5 and I was worried about the long term effects of that. Had I kept it my plan was to replace the torque converter and install a shift kit since the TC is a weak link in the vast majority of the GM transmissions.

When towing I put the truck in "L" and moved the selected gear to "8" which locked out 9th and 10th. I typically run around 65 MPH and this kept me around 2100 RPM which experience has found is where this engine likes to live when towing. I would like to see some sort of retained memory when using the "L" selection. It becomes tedious when every time you get back in the truck you have to reselect the gear. It would seem that GM could retain that info when connected to a trailer but at this point mine doesnt. A small thing but when towing a lot it becomes a small annoyance.

After all the 4000 miles of driving using the trucks fuel economy monitors and well as the ones on my Scangage I came to the conclusion that 8th gear was best suited for this load. I did try using 9th gear a few times which put the truck in the 1700 RPM range but it made no improvement to the mileage either instant or longer term. I even went so far to allow the 9th gear upshift on the longer downgrades and didn't see any advantage. It did raise the trans temp 2 degrees with the additional shifting when selecting 9th. My trans temps were around 145-160 consistently no matter the terrain. The only time I saw 180 was in Florida during an I-4 stop and go session that lasted about an hour. It would seem the trans cooler on this truck is solid.

I would not tow heavy with this truck without a Scangage. I played with the display several times and have the 3 screens setup for similar base gages with a few varied between screens. I did have an issue with the Scangage not booting up occasionally and I contacted them. When I first got it in December I downloaded the latest program on WIFI but by the time I contacted them in March they had a new update that supposedly corrected this. I did however have an issue yesterday with it not booting up after a remote start sequence. I plan to contact them with that info and will follow up.

My mileage averaged about 8.25 to 8.5 with a couple of stretches of sub 8 and a couple of 9.25-9.5 This setup is very sensitive to head winds and the gasser lacking the diesels torque is most evident when windy. Its not bad but the mileage suffers. Going through Ohio yesterday was pretty windy and depending on the direction brought down my mpg to a little over 8. Once you get North of Dayton its pretty flat and with low or no wind the truck is capable of 9mpg but that rarely happens in Ohio in the spring.

I do have plans for an exhaust mod but I haven't decided between the 3 1/2" Borla muffler or the MBRP kit. The Borla is almost a direct fit with the stock muffler cut out and 2 band clamps but I like the MBRP sound. The price difference is substantial but I dont want to drop $300 on the Borla and then find its too loud. Stay tunes for that one.

Overall I am still please with the setup and economy of the gas engine, consider the price of DEF along with the added cost of diesel it doesn't come close to covering the price split. Its hard to argue with the diesel torque though. If I felt the reliability of the Dmax and the DEF weren't an issue I would probably own one but in today world it doesn't add up for me, although I do have a feeler out for info on when the 8.3 comes online. LOL

Hopefully you found this rant useful.

Scott

My sg3 has had that no boot before too. Rarely but it has happened. I just quickly unplug the cord from the back of the sg and immediately plug back in and it’s all good. Still annoying. Never once happened to my other two sg models. Let me know what you hear.

64BAwagon · March 29

The fix they advised was to upload the new firmware Version 1.24.

When I got mine in Dec 2023 the firmware that I uploaded was Version 1.23 so this was an update. I think the latest issue was the fact that I remote started it. Since none of the dash display comes online during a remote it may impact the SG3. When I got in the truck and pushed the start button to operate it after the remote the SG3 display did not come on. I didnt notice it right away but it was dark out and I could see a faint glow on the screen. It also could have been the thin air in TN ? hard to say. I will post the response from SG.

Capt Bob · March 29

3 hours ago, 64BAwagon said:

The fix they advised was to upload the new firmware Version 1.24.

When I got mine in Dec 2023 the firmware that I uploaded was Version 1.23 so this was an update. I think the latest issue was the fact that I remote started it. Since none of the dash display comes online during a remote it may impact the SG3. When I got in the truck and pushed the start button to operate it after the remote the SG3 display did not come on. I didnt notice it right away but it was dark out and I could see a faint glow on the screen. It also could have been the thin air in TN ? hard to say. I will post the response from SG.

Interesting. I too purchased in December and had the same symptoms when remote starting. I chalked it up due to the cold (for Florida) night. I also experience another quirk on occasion. The daily fuel mileage MPG screen(far left module) will read INF. After a short distance it resets to 9999 and rapidly counts down as I drive. Again, this occurs on the remote start and I contributed it to the cold weather. Thing is, its happened in warmer weather also. I’ll try the update. Otherwise, the SG3 has worked very well.

64BAwagon · March 29

I received a reply from SG and they state that the SG is noticing a voltage rise so it turns on but since the ECU is not reporting data it goes back to sleep. They state that tapping the screen will wake it up but I attempted that and was unsuccessful. Their remedy was this:

From the Home screen choose MORE>SETUP>ADVANCE>COMPATIBILITY>arrow pointing down to WAKE UP DELAY>EDIT SETTING> change to LOW.

They state this should solve the issue when remote starting.

Scott

Capt Bob · March 29

3 hours ago, 64BAwagon said:

I received a reply from SG and they state that the SG is noticing a voltage rise so it turns on but since the ECU is not reporting data it goes back to sleep. They state that tapping the screen will wake it up but I attempted that and was unsuccessful. Their remedy was this:

From the Home screen choose MORE>SETUP>ADVANCE>COMPATIBILITY>arrow pointing down to WAKE UP DELAY>EDIT SETTING> change to LOW.

They state this should solve the issue when remote starting.

Scott

Excellent Scott,

Thanks!

Pryme · March 29

3 hours ago, 64BAwagon said:

I received a reply from SG and they state that the SG is noticing a voltage rise so it turns on but since the ECU is not reporting data it goes back to sleep. They state that tapping the screen will wake it up but I attempted that and was unsuccessful. Their remedy was this:

From the Home screen choose MORE>SETUP>ADVANCE>COMPATIBILITY>arrow pointing down to WAKE UP DELAY>EDIT SETTING> change to LOW.

They state this should solve the issue when remote starting.

Scott

I’ll be looking it this. Thank you

64BAwagon · March 30

I started my truck by remote this morning to test the changes that the SG folks suggested.

I got the same results. The screen was dark when I opened the door. It did not come online with tapping the screen. I used the button to turn the truck on while it was still running from the remote start. The dashboard comes on but still no SG. I then unplugged the unit and plugged it back in and it came online.

Since I made the initial changes over a week ago the SG has operated properly when started by being inside the truck. It has not operated correctly the 2 times I remote started. It would seem we still have some work to do. I will advise the SG folks and report any new instructions.

Scott