WaveZero
Member
I'm going to get my car re-dynoed later next week, running a ~E30 flex fuel tune. I will post back the results and see if my performance has been impacted. There's a lag or something I can't put my finger on it yet.
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ky.supra
Well-Known Member
Yup, I have experience lag and the OTS tune (93 Stage 2) doesn't run as smooth as it did before. My car exhaust volume also increased a notch or two. I've done multiple pulls and runs with my friends behind me and they also noticed it too. Let us know if you experience the same issues after your dyno day.
Jakub (remote bimmer) has coded my car back to stock and refunded me but I will still follow this thread to see if anything changes
Rensuhlo
Well-Known Member
Was excited for this, but may hold off. Kudos to Bimmer-Remote for handling it in a professional manner, unlike the likes of say...Fitment Industries.
But I'll still follow it along to watch @BMWAF make a fool of hisself as he usually does. 1 like = 1 prayer to keep him contained to the austrailia subforums.
But I'll still follow it along to watch @BMWAF make a fool of hisself as he usually does. 1 like = 1 prayer to keep him contained to the austrailia subforums.
WaveZero
Member
Based on the info @ky.supra posted and what I can gather, I got a friend to do a binary analysis of the original Supra ROM and the G29/Z4 ROM used after the remote start conversion, mainly looking at the engine calibration, pedal behaviour and exhaust valve logic.
My old Supra ROM is:
5D553C8207
J29 / B58B30M1 / TUSA-ULEV70
The newer remote start ROM is:
5D5532DC05
G29 / B58B30M1 / ROW-EU6
So it pretty much confirms the remote start conversion is using a G29 Z4 software branch. The good news (for pre-updated Supra B58 engine) is both binaries identify the engine as B58B30M1, so it isn't flashing the later 6 port B58B30O1 engine firmware onto the early Supra.
From the binary comparison, the important engine stuff is basically identical:
The G29/Z4 software generally targets slightly cooler normal coolant temperatures.
For example:
Supra: 98°C / 97°C / 96°C / 95°C
vs
G29: 95°C / 95°C / 95°C / 95°C
Cold oil pressure is also slightly higher in a few very cold temperature cells.
For example at around -30°C:
Supra @ 600 rpm: ~3.3 bar
G29 @ 600 rpm: ~4.0 bar
and:
Supra @ 1300 rpm: ~3.3 bar
G29 @ 1300 rpm: ~4.0 bar
Otherwise the oil pressure maps are basically the same.
One thing that could explain why the car feels a bit different is the pedal/driver demand maps.
The G29 software is slightly softer in some of the mid pedal areas in Normal, Sport and Sport+.
A few examples:
Normal:
40.39 -> 38.81
54.54 -> 52.42
67.61 -> 64.93
Sport:
44.98 -> 43.21
61.39 -> 59.00
76.83 -> 73.77
Sport+:
48.41 -> 46.50
66.11 -> 63.54
Most of the tables are still identical, but there are enough differences that you could genuinely notice a slightly softer throttle/torque response in some parts of the pedal range.
There was also an interesting difference with the exhaust valve.
The warm start valve settings themselves are the same, but one of the pedal controlled exhaust valve speed thresholds changes from:
Supra: 0 km/h
to:
G29: 17.5 km/h
So under one of the operating modes the Z4 software won't start using pedal dependent valve control until the car is moving above about 17.5 km/h.
That could potentially explain some of the weird exhaust valve behaviour I've noticed since the remote start conversion.
There was also a small fueling difference in one rich lambda limit table. 33 out of 36 cells were identical, but three low load cells changed from roughly:
13.23 AFR equivalent
to:
10.29 AFR equivalent
The higher load area was identical though, so it doesn't look like the G29 software is doing anything radically different under boost.
Overall, based on the binary comparison, I'm a lot less concerned about running the G29 branch and it should be fully tuneable.
The core engine protection and hardware sensitive maps are basically identical and both ROMs are specifically for the B58B30M1. The bigger differences seem to be vehicle behaviour, emissions configuration, pedal mapping, cooling strategy and things like the exhaust valve rather than fundamental engine control.
You need to force MHD to use G29 050_220 ROM for MHD+ support as per @ky.supra post.
My old Supra ROM is:
5D553C8207
J29 / B58B30M1 / TUSA-ULEV70
The newer remote start ROM is:
5D5532DC05
G29 / B58B30M1 / ROW-EU6
So it pretty much confirms the remote start conversion is using a G29 Z4 software branch. The good news (for pre-updated Supra B58 engine) is both binaries identify the engine as B58B30M1, so it isn't flashing the later 6 port B58B30O1 engine firmware onto the early Supra.
From the binary comparison, the important engine stuff is basically identical:
- Turbo/wastegate flow model is identical
- VANOS warm intake maps are identical
- HPFP rail pressure maps are identical
- Knock detection maps are identical
- Component protection lambda maps are identical
- EGT protection limits are identical
- Maximum coolant temperature target is identical
The G29/Z4 software generally targets slightly cooler normal coolant temperatures.
For example:
Supra: 98°C / 97°C / 96°C / 95°C
vs
G29: 95°C / 95°C / 95°C / 95°C
Cold oil pressure is also slightly higher in a few very cold temperature cells.
For example at around -30°C:
Supra @ 600 rpm: ~3.3 bar
G29 @ 600 rpm: ~4.0 bar
and:
Supra @ 1300 rpm: ~3.3 bar
G29 @ 1300 rpm: ~4.0 bar
Otherwise the oil pressure maps are basically the same.
One thing that could explain why the car feels a bit different is the pedal/driver demand maps.
The G29 software is slightly softer in some of the mid pedal areas in Normal, Sport and Sport+.
A few examples:
Normal:
40.39 -> 38.81
54.54 -> 52.42
67.61 -> 64.93
Sport:
44.98 -> 43.21
61.39 -> 59.00
76.83 -> 73.77
Sport+:
48.41 -> 46.50
66.11 -> 63.54
Most of the tables are still identical, but there are enough differences that you could genuinely notice a slightly softer throttle/torque response in some parts of the pedal range.
There was also an interesting difference with the exhaust valve.
The warm start valve settings themselves are the same, but one of the pedal controlled exhaust valve speed thresholds changes from:
Supra: 0 km/h
to:
G29: 17.5 km/h
So under one of the operating modes the Z4 software won't start using pedal dependent valve control until the car is moving above about 17.5 km/h.
That could potentially explain some of the weird exhaust valve behaviour I've noticed since the remote start conversion.
There was also a small fueling difference in one rich lambda limit table. 33 out of 36 cells were identical, but three low load cells changed from roughly:
13.23 AFR equivalent
to:
10.29 AFR equivalent
The higher load area was identical though, so it doesn't look like the G29 software is doing anything radically different under boost.
Overall, based on the binary comparison, I'm a lot less concerned about running the G29 branch and it should be fully tuneable.
The core engine protection and hardware sensitive maps are basically identical and both ROMs are specifically for the B58B30M1. The bigger differences seem to be vehicle behaviour, emissions configuration, pedal mapping, cooling strategy and things like the exhaust valve rather than fundamental engine control.
You need to force MHD to use G29 050_220 ROM for MHD+ support as per @ky.supra post.
WaveZero
Member
A bit of a follow up to the comparison above.
I got my friend to dig deeper into the two stock binaries, specifically looking at the torque/throttle side of things to see if there was anything obvious that would explain why the car can feel a bit different on the G29 ROM.
Interestingly, most of the obvious stuff is actually identical between the two.
The main load to torque model is identical across all 360 cells, max torque limit is 650 Nm on both, the vehicle/application torque limiter is the same, the auto transmission gear torque limiter is the same, throttle response filtering is the same, max throttle target is basically the same, and the wastegate/turbo/boost control maps checked were also identical.
The main wastegate pre-control table was literally 144/144 cells identical.
So the simple explanation of "the G29 ROM just has softer throttle or slower boost response" doesn't fully explain the differences.
One of the bigger differences my friend found is the IAT (Intake Air Temperate) based torque limiting.
The temperature breakpoints are:
Supra: 65 / 67 / 72 / 75 / 82 / 92C
G29: 65 / 66 / 69 / 72 / 90 / 92C
At around 72C IAT the G29 can actually be more restrictive.
1000 rpm: 600 Nm -> 462 Nm = -138 Nm / -23%
3000 rpm: 600 Nm -> 492 Nm = -108 Nm / -18%
4000 rpm: 530 Nm -> 492 Nm = -38 Nm / -7.2%
5000 rpm: 490 Nm -> 460 Nm = -30 Nm / -6.1%
But once it gets really hot, it flips the other way.
The Supra has a much bigger derate point around 82C, while the G29 doesn't hit the equivalent point until closer to 90C.
At roughly 82C:
1000 rpm: Supra 231 Nm vs G29 ~334 Nm = +103 Nm / +44.6%
3000 rpm: Supra 261 Nm vs G29 ~364 Nm = +103 Nm / +39.5%
4000 rpm: Supra 244 Nm vs G29 ~354 Nm = +110 Nm / +45.1%
So the G29 is more restrictive around the 70 to 75C range, but significantly less restrictive once things are properly heat soaked.
My friend also found a difference in one of the dynamic ignition correction tables when the engine is both hot and pulling timing.
At around 70C IAT and roughly -4.5° of retard:
Supra: 0.816
G29: 0.695
Difference: -0.121 / -14.8%
At around -2°:
Supra: 0.672
G29: 0.551
Difference: -0.121 / -18.0%
At little or no timing correction they're basically the same.
Another interesting one my friend picked up was a transmission related dynamic correction table. 39 out of 40 values are identical. The only different cell is at 0 km/h in one internal state:
Supra: 0.9961
G29: 0.8984
Difference: -0.0977 / -9.8%
Everything at 10, 30 and 120 km/h is identical, so it probably isn't something you'd notice during normal driving, but it may relate to some stationary/take off state.
At this point the main takeaway from the deeper binary comparison is that the obvious pedal, torque, throttle, boost and turbo control maps are overwhelmingly similar between the two ROMs.
The more noticeable differences seem to be conditional behaviour, especially when the car is hot, heat soaked or pulling timing.
If the car feels different during normal cool driving, I'm leaning more towards MHD's ROM specific Stage 2/MHD+ calibration, coding differences, or logic buried deeper in the executable rather than the main stock torque or throttle maps themselves.
I got my friend to dig deeper into the two stock binaries, specifically looking at the torque/throttle side of things to see if there was anything obvious that would explain why the car can feel a bit different on the G29 ROM.
Interestingly, most of the obvious stuff is actually identical between the two.
The main load to torque model is identical across all 360 cells, max torque limit is 650 Nm on both, the vehicle/application torque limiter is the same, the auto transmission gear torque limiter is the same, throttle response filtering is the same, max throttle target is basically the same, and the wastegate/turbo/boost control maps checked were also identical.
The main wastegate pre-control table was literally 144/144 cells identical.
So the simple explanation of "the G29 ROM just has softer throttle or slower boost response" doesn't fully explain the differences.
One of the bigger differences my friend found is the IAT (Intake Air Temperate) based torque limiting.
The temperature breakpoints are:
Supra: 65 / 67 / 72 / 75 / 82 / 92C
G29: 65 / 66 / 69 / 72 / 90 / 92C
At around 72C IAT the G29 can actually be more restrictive.
1000 rpm: 600 Nm -> 462 Nm = -138 Nm / -23%
3000 rpm: 600 Nm -> 492 Nm = -108 Nm / -18%
4000 rpm: 530 Nm -> 492 Nm = -38 Nm / -7.2%
5000 rpm: 490 Nm -> 460 Nm = -30 Nm / -6.1%
But once it gets really hot, it flips the other way.
The Supra has a much bigger derate point around 82C, while the G29 doesn't hit the equivalent point until closer to 90C.
At roughly 82C:
1000 rpm: Supra 231 Nm vs G29 ~334 Nm = +103 Nm / +44.6%
3000 rpm: Supra 261 Nm vs G29 ~364 Nm = +103 Nm / +39.5%
4000 rpm: Supra 244 Nm vs G29 ~354 Nm = +110 Nm / +45.1%
So the G29 is more restrictive around the 70 to 75C range, but significantly less restrictive once things are properly heat soaked.
My friend also found a difference in one of the dynamic ignition correction tables when the engine is both hot and pulling timing.
At around 70C IAT and roughly -4.5° of retard:
Supra: 0.816
G29: 0.695
Difference: -0.121 / -14.8%
At around -2°:
Supra: 0.672
G29: 0.551
Difference: -0.121 / -18.0%
At little or no timing correction they're basically the same.
Another interesting one my friend picked up was a transmission related dynamic correction table. 39 out of 40 values are identical. The only different cell is at 0 km/h in one internal state:
Supra: 0.9961
G29: 0.8984
Difference: -0.0977 / -9.8%
Everything at 10, 30 and 120 km/h is identical, so it probably isn't something you'd notice during normal driving, but it may relate to some stationary/take off state.
At this point the main takeaway from the deeper binary comparison is that the obvious pedal, torque, throttle, boost and turbo control maps are overwhelmingly similar between the two ROMs.
The more noticeable differences seem to be conditional behaviour, especially when the car is hot, heat soaked or pulling timing.
If the car feels different during normal cool driving, I'm leaning more towards MHD's ROM specific Stage 2/MHD+ calibration, coding differences, or logic buried deeper in the executable rather than the main stock torque or throttle maps themselves.
chillvibe704
Member
Adding another data point to this thread that I had this done on my 2024 auto, I'm not tuned, and the exhaust flap issue is present as others have mentioned.
They did defeat the auto start/stop for free which I was not able to via Bimmercode previously. All of my previous Bimmercode changes remained after the coding was done.
I'm happy but it sounds like I may run into some weirdness when I go to tune my car in the future. I'll deal with that when the time comes.
They did defeat the auto start/stop for free which I was not able to via Bimmercode previously. All of my previous Bimmercode changes remained after the coding was done.
I'm happy but it sounds like I may run into some weirdness when I go to tune my car in the future. I'll deal with that when the time comes.
Luftdad
Well-Known Member
- First Name
- Del
- Joined
- Apr 9, 2025
- Threads
- 12
- Messages
- 48
- Reaction score
- 10
- Location
- The Woodlands , Texas
- Car(s)
- 2024 Toyota Supra 3.0 Premium
I just finished the installation. Everything works as promisedI’ve updated the product link with all the clarifications. Hope everything is clear now!
https://bimmer-remote.com/products/toyota-supra-remote-start-coding-activation
OP
OP
- Thread starter
- #143
Thank you for your recommendation
Luftdad
Well-Known Member
- First Name
- Del
- Joined
- Apr 9, 2025
- Threads
- 12
- Messages
- 48
- Reaction score
- 10
- Location
- The Woodlands , Texas
- Car(s)
- 2024 Toyota Supra 3.0 Premium
I do have one advisory. Once the software is installed you can start the car remotely using Supra Connect. But be aware that when you push the fan symbol the car starts remotely.. I did it by mistake and freaked out my wife who was in the garage at the time
WaveZero
Member
A bit of a follow up after all the digging into the old Supra J29 ROM vs the newer G29/Z4 ROM used for the remote start conversion.
I also went back through my old dyno runs to see whether there was actually any evidence that the car had lost power after moving to the G29 software branch.
At first the December 2025 E30 result looked pretty concerning because the car made 472.4 hp / 656.9 Nm before the remote start conversion, where as the recent E30 run only made 434.2 hp.
But after looking at it properly, I don't think it's fair to treat those as a direct apples-to-apples comparison.
The December run was before I had xHP Stage 3, and I think the car may have been run in 5th rather than 6th (5th isn't 1:1 gear ratio vs 6th gear's 1:1) - the stock TCU tune does not allow the car to be dyno in 6th gear. The dyno sheet also shows derived engine RPM/torque, so the exact torque number and where it occurs may be affected by the gear ratio the dyno was using. 5th gear gives higher power and torque figures due to it being approximation derived from engine RPM/Torque.
There was also quite a bit of variation between the E30 runs that day anyway:
454.7 hp
459.0 hp
466.7 hp
472.4 hp
So 472 hp was the best run, rather than the car consistently making 472 hp every pull.
Dyno comparison
December 2025 - Original J29 Supra ROM + MHD+ - E30 /w 98RON
Power: 472.4 hp
Torque: 656.9 Nm
Notes: No xHP Stage 3, possibly run in 5th gear, with derived RPM/torque and better fuel quality supply vs now.
July 2026 - Original J29 Supra ROM + MHD+ - E47 /w 98RON
Power: 459.7 hp
Torque: 611.7 Nm
Notes: Best recent baseline before the remote start conversion. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - 98RON
Power: 406.2 hp
Torque: 543.7 Nm
Notes: Significant timing corrections in the MHD log. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - E30 w/ 98RON
Power: 434.2 hp
Torque: 601.4 Nm
Notes: Very clean timing with basically no corrections. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - E40 /w 98RON
Power: 450.2 hp
Torque: 627.4 Nm
Notes: More boost and load than E30. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - E50 /w 98RON
Power: 465.3 hp
Torque: 628.7 Nm
Notes: Highest result from the current setup. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
The July E47 run is probably the more useful comparison because it's much closer to the current setup and was only shortly before the remote start conversion.
That comparison is:
Old J29 E47: 459.7 hp
vs
Current G29 E50: 465.3 hp
So the current setup is actually 5.6 hp higher, which doesn't really support the theory that the G29 ROM itself has simply lost power.
The more interesting difference seems to be how the current MHD+ flex fuel calibration scales the car with ethanol.
The latest results were:
98RON: 406.2 hp
E30: 434.2 hp (+28.0 hp)
E40: 450.2 hp (+16.0 hp)
E50: 465.3 hp (+15.1 hp)
The MHD logs also explain quite a bit of that.
The current 98RON run had some pretty ugly timing corrections, up to roughly -5.7 degrees, while the E30 run was basically completely clean with no meaningful cylinder corrections during the pull.
So regardless of the reason, the current 98RON fuel clearly wasn't very happy on the tune.
I've also had the feeling that the quality of 98RON in Australia hasn't been as consistent lately, especially with everything going on with global fuel supply. My mechanic mentioned that several tuners who use his workshop's dyno have also been complaining about seeing more timing corrections than usual.
What is interesting is that even though the E30 log was extremely clean, the current MHD+ calibration doesn't seem to push particularly hard at E30.
As ethanol increases, MHD progressively asks for more load and boost.
By around 6000 rpm the logs are roughly:
E30: ~17.8 psi / ~177% load
E40: ~18.7 psi / ~182% load
E50: ~20.1 psi / ~189% load
So the current flex map appears to use E30 mainly to get the octane/timing benefit, then starts adding noticeably more load as you get into E40-E50.
That could be another explanation why the current E30 result looks quite low compared with my old E30 dyno sheet without necessarily meaning the G29 software itself is down on power.
The other thing that makes me cautious about comparing the 2025 old and new results directly is that quite a few things have changed:
Original J29 ROM vs newer G29 ROM:
If anything, the closest pre/post comparison I have is roughly 460 hp on E47 before the remote start conversion vs 465 hp on E50 now, which is basically the same ballpark.
The bigger difference seems to be how the current MHD+ calibration delivers the power and how aggressively it scales load with ethanol, rather than the underlying G29 engine software simply making less power.
Overall, if you’re only looking at the tuning side and peak performance, there’s little to no evidence from my testing to support the claim that the remote start conversion reduces performance or negatively affects the tune. The car is still making essentially the same peak power as it was before, and in my most recent testing it actually made slightly more.
That doesn’t mean nothing else has changed in the DME software though. There are definitely some differences between the original J29 Supra firmware and the G29 Z4 branch, including things like pedal/driver demand behaviour, some transmission related dynamic timing corrections, cooling targets and other background strategies. Those sorts of changes may affect how the car feels or behaves in certain situations without necessarily showing up as a loss in peak dyno power.
The European Z4 software also uses different coolant temperature targets in some operating areas, so that could potentially affect how the car behaves thermally. There are some AFR/lambda related differences in the stock binaries as well, although once you flash an MHD tune, MHD may overwrite or modify a lot of those values anyway.
For me personally, I’m happy to stay on the remote start software. My car is already out of warranty, so I’m not particularly worried about that side of it. If the car was still under Toyota warranty, I’d probably be a bit more cautious because I have no idea how Toyota would react if they plugged into the car and saw the DME running a G29 Z4 software branch instead of the expected J29 Supra firmware, or whether that could affect a warranty claim.
I’ll probably write up a proper review of the remote start conversion once I’ve had a bit more time with it, and I may do a video as well if I get the chance. I’m flying out of country in a few days and will be away for around three months, so it may have to wait until I’m back.
I also went back through my old dyno runs to see whether there was actually any evidence that the car had lost power after moving to the G29 software branch.
At first the December 2025 E30 result looked pretty concerning because the car made 472.4 hp / 656.9 Nm before the remote start conversion, where as the recent E30 run only made 434.2 hp.
But after looking at it properly, I don't think it's fair to treat those as a direct apples-to-apples comparison.
The December run was before I had xHP Stage 3, and I think the car may have been run in 5th rather than 6th (5th isn't 1:1 gear ratio vs 6th gear's 1:1) - the stock TCU tune does not allow the car to be dyno in 6th gear. The dyno sheet also shows derived engine RPM/torque, so the exact torque number and where it occurs may be affected by the gear ratio the dyno was using. 5th gear gives higher power and torque figures due to it being approximation derived from engine RPM/Torque.
There was also quite a bit of variation between the E30 runs that day anyway:
454.7 hp
459.0 hp
466.7 hp
472.4 hp
So 472 hp was the best run, rather than the car consistently making 472 hp every pull.
Dyno comparison
December 2025 - Original J29 Supra ROM + MHD+ - E30 /w 98RON
Power: 472.4 hp
Torque: 656.9 Nm
Notes: No xHP Stage 3, possibly run in 5th gear, with derived RPM/torque and better fuel quality supply vs now.
July 2026 - Original J29 Supra ROM + MHD+ - E47 /w 98RON
Power: 459.7 hp
Torque: 611.7 Nm
Notes: Best recent baseline before the remote start conversion. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - 98RON
Power: 406.2 hp
Torque: 543.7 Nm
Notes: Significant timing corrections in the MHD log. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - E30 w/ 98RON
Power: 434.2 hp
Torque: 601.4 Nm
Notes: Very clean timing with basically no corrections. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - E40 /w 98RON
Power: 450.2 hp
Torque: 627.4 Nm
Notes: More boost and load than E30. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
August 2026 - G29 050_220 + MHD+ - E50 /w 98RON
Power: 465.3 hp
Torque: 628.7 Nm
Notes: Highest result from the current setup. xHP Stage 3 in sixth gear. Fuel quality standards have dropped in Australia.
The July E47 run is probably the more useful comparison because it's much closer to the current setup and was only shortly before the remote start conversion.
That comparison is:
Old J29 E47: 459.7 hp
vs
Current G29 E50: 465.3 hp
So the current setup is actually 5.6 hp higher, which doesn't really support the theory that the G29 ROM itself has simply lost power.
The more interesting difference seems to be how the current MHD+ flex fuel calibration scales the car with ethanol.
The latest results were:
98RON: 406.2 hp
E30: 434.2 hp (+28.0 hp)
E40: 450.2 hp (+16.0 hp)
E50: 465.3 hp (+15.1 hp)
The MHD logs also explain quite a bit of that.
The current 98RON run had some pretty ugly timing corrections, up to roughly -5.7 degrees, while the E30 run was basically completely clean with no meaningful cylinder corrections during the pull.
So regardless of the reason, the current 98RON fuel clearly wasn't very happy on the tune.
I've also had the feeling that the quality of 98RON in Australia hasn't been as consistent lately, especially with everything going on with global fuel supply. My mechanic mentioned that several tuners who use his workshop's dyno have also been complaining about seeing more timing corrections than usual.
What is interesting is that even though the E30 log was extremely clean, the current MHD+ calibration doesn't seem to push particularly hard at E30.
As ethanol increases, MHD progressively asks for more load and boost.
By around 6000 rpm the logs are roughly:
E30: ~17.8 psi / ~177% load
E40: ~18.7 psi / ~182% load
E50: ~20.1 psi / ~189% load
So the current flex map appears to use E30 mainly to get the octane/timing benefit, then starts adding noticeably more load as you get into E40-E50.
That could be another explanation why the current E30 result looks quite low compared with my old E30 dyno sheet without necessarily meaning the G29 software itself is down on power.
The other thing that makes me cautious about comparing the 2025 old and new results directly is that quite a few things have changed:
Original J29 ROM vs newer G29 ROM:
- Different MHD ROM-specific calibration
- xHP Stage 3
- Possibly different dyno gear
- Different fuel batches
- Different ambient conditions
- Different ethanol content
If anything, the closest pre/post comparison I have is roughly 460 hp on E47 before the remote start conversion vs 465 hp on E50 now, which is basically the same ballpark.
The bigger difference seems to be how the current MHD+ calibration delivers the power and how aggressively it scales load with ethanol, rather than the underlying G29 engine software simply making less power.
Overall, if you’re only looking at the tuning side and peak performance, there’s little to no evidence from my testing to support the claim that the remote start conversion reduces performance or negatively affects the tune. The car is still making essentially the same peak power as it was before, and in my most recent testing it actually made slightly more.
That doesn’t mean nothing else has changed in the DME software though. There are definitely some differences between the original J29 Supra firmware and the G29 Z4 branch, including things like pedal/driver demand behaviour, some transmission related dynamic timing corrections, cooling targets and other background strategies. Those sorts of changes may affect how the car feels or behaves in certain situations without necessarily showing up as a loss in peak dyno power.
The European Z4 software also uses different coolant temperature targets in some operating areas, so that could potentially affect how the car behaves thermally. There are some AFR/lambda related differences in the stock binaries as well, although once you flash an MHD tune, MHD may overwrite or modify a lot of those values anyway.
For me personally, I’m happy to stay on the remote start software. My car is already out of warranty, so I’m not particularly worried about that side of it. If the car was still under Toyota warranty, I’d probably be a bit more cautious because I have no idea how Toyota would react if they plugged into the car and saw the DME running a G29 Z4 software branch instead of the expected J29 Supra firmware, or whether that could affect a warranty claim.
I’ll probably write up a proper review of the remote start conversion once I’ve had a bit more time with it, and I may do a video as well if I get the chance. I’m flying out of country in a few days and will be away for around three months, so it may have to wait until I’m back.
Last edited:
OP
OP
- Thread starter
- #146
Great write up, thank u!
celesteMk5
Member
I’m dealing waiting on ECUTEK with my rom dump after this remote start and unlocking. Tuner said my ECU is not supported.
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