Not joined yet? Register for free and enjoy features such as alerts, private messaging and viewing latest posts and topics.
35is upgrades (stage2+)
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
Winter is coming... and fortunately the laws here will change in Jan regarding importing, so all being well, looks like I'll be able to keep the car...
A great price came up for some new parts, so I took the plunge and rather than doing it bit by bit it made sense to do it all when the car is already on the ramps.
- VRSF downpipes
- Bigdaddies mini-cat o2 sensor mod
- VRSF inlets
- VRSF dual cone intake
- TurboSmart dual port with BOV (set to 50/50) and Z4 pipework
- BMS FMIC (some cheap chinese clone, but surprised how well made it is, bar+plate, robot welded, nicely done for the money!)
- BMS Z4 ChargePipe (black anodised alloy pipe)
- All vac hoses replaced with 3.5" performance silicon hosing
- oil catch can and BMS RB PCV upgrade (with option to close off completely and re-route through the catch can, have to see how that will work)
- 6x NGK plugs (1 step cooler, gapped to 0.22")
- Change oil (also going 10w60w in march), oil filter, pollen filter, cabin filter
- Clean intake valves if needed
- Amazon Fire Tab HD 8" for MHD/logging, sat on a brodit clip
- Custom MHD tune by Ken @ WedgePerformance (he's the author of the MHD OTS maps)
We are aiming for 400whp on 98/102 octane (470~ crank), lets see what happens (expecting 370whp but we can hope )! can't get any ethanol over here so 102 is the theoretical max from the pump.
Pics to follow
A great price came up for some new parts, so I took the plunge and rather than doing it bit by bit it made sense to do it all when the car is already on the ramps.
- VRSF downpipes
- Bigdaddies mini-cat o2 sensor mod
- VRSF inlets
- VRSF dual cone intake
- TurboSmart dual port with BOV (set to 50/50) and Z4 pipework
- BMS FMIC (some cheap chinese clone, but surprised how well made it is, bar+plate, robot welded, nicely done for the money!)
- BMS Z4 ChargePipe (black anodised alloy pipe)
- All vac hoses replaced with 3.5" performance silicon hosing
- oil catch can and BMS RB PCV upgrade (with option to close off completely and re-route through the catch can, have to see how that will work)
- 6x NGK plugs (1 step cooler, gapped to 0.22")
- Change oil (also going 10w60w in march), oil filter, pollen filter, cabin filter
- Clean intake valves if needed
- Amazon Fire Tab HD 8" for MHD/logging, sat on a brodit clip
- Custom MHD tune by Ken @ WedgePerformance (he's the author of the MHD OTS maps)
We are aiming for 400whp on 98/102 octane (470~ crank), lets see what happens (expecting 370whp but we can hope )! can't get any ethanol over here so 102 is the theoretical max from the pump.
Pics to follow
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- markplant
- Lifer
- Posts: 3674
- Joined: Mon Jul 21, 2014 8:16 pm
- Location: Sheffield
35is upgrades (stage2+)
I'll just say wow
3.0 Manual. Sterling Grey. Cream leather Electric an Heated. Professional Navigation/Sony tablet replacement. Storm Werks . an parts waiting to be fitted
-
- Member
- Posts: 403
- Joined: Tue Jul 16, 2013 10:58 am
- Location: Cornwall
35is upgrades (stage2+)
I've got most of the parts on the list and I didn't get anywhere near those figures (401hp), however, I'll be very interested to see how you get on I'm still waiting for my new turbos to turn up.... can't even remember how many months ago I ordered them
I've not tried the new v8 beta map but I can't see it making a huge difference.
I've not tried the new v8 beta map but I can't see it making a huge difference.
- R.E92
- Senior Member
- Posts: 1644
- Joined: Wed Dec 04, 2013 10:10 am
35is upgrades (stage2+)
400whp is a decent goal and should be easily achievable on 93 octane, I'd be aiming higher if using 102 octane (unless you mean RON).
There's a lot of mods there but only the downpipes and intercooler will give you more power. I'd be tempted to upgrade to some Pure turbos since you are going to all the effort of doing that.
There's a lot of mods there but only the downpipes and intercooler will give you more power. I'd be tempted to upgrade to some Pure turbos since you are going to all the effort of doing that.
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
Yes, most of the mods are in support, the inlets should really help as well.
http://www.vr-speed.com/vrsf-oem-locati ... 1m-z4.html
I want to get rid of every bit of plastic on the air side. Any boost leaks or problems with the DVs will cause the turbos to work extra hard for no gain, plus I want to remove altogether (or at least significant reduce) the oil coming into the intake.
I guess it's more in search of the "stable" high boost at maximum efficiency. I've been researching what the guys over in the US and AU are doing for over a year and this seems to be about as far as I can go without hybrid turbos.
I'm trying to upgrade the weakest parts, especially if it's already all apart. I don't want the chargepipe exploding either
http://www.vr-speed.com/vrsf-oem-locati ... 1m-z4.html
I want to get rid of every bit of plastic on the air side. Any boost leaks or problems with the DVs will cause the turbos to work extra hard for no gain, plus I want to remove altogether (or at least significant reduce) the oil coming into the intake.
I guess it's more in search of the "stable" high boost at maximum efficiency. I've been researching what the guys over in the US and AU are doing for over a year and this seems to be about as far as I can go without hybrid turbos.
I'm trying to upgrade the weakest parts, especially if it's already all apart. I don't want the chargepipe exploding either
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
R.E92 if I go any further after this it would be in order of suspension and traction first, then later on more power. This is enough for now.
1. LSD / Ring & Pinion upgrade, upgraded rear bushes / tighten up the rear end as much as possible (some guys in the US broke their rear end twice on launching - until they stopped the wheel hop and flex. it uses E46 non-m bushes and apparently is quite sloppy).
2. M3 front control arms and adjustable rear camber arms and top mounts / more bushing upgrades
3. 435i M sport or equiv. front brakes (not sure what options we have on the rear with the ebrake). Also saw E60 M5 front brake swap, this looks temping
If after all that is done (realistically this is 1-2 years process), then I'll consider hybrid turbos but also do the SSP upgrades at the same time (900 lb/ft clutches, oil cooler upgrade and basket), upgraded fueling and then aim for 600 WHP, but I'm not sure how viable that is without at least E30 / water injection / meth? I think you need to run at least 25+ PSI, might then want to swap out the pistons if you're going to all that trouble. Then we're talking big money. I still have 2 balcony extension conversions, a garden and a kitchen to complete. I won't be allowed until it's all done
1. LSD / Ring & Pinion upgrade, upgraded rear bushes / tighten up the rear end as much as possible (some guys in the US broke their rear end twice on launching - until they stopped the wheel hop and flex. it uses E46 non-m bushes and apparently is quite sloppy).
2. M3 front control arms and adjustable rear camber arms and top mounts / more bushing upgrades
3. 435i M sport or equiv. front brakes (not sure what options we have on the rear with the ebrake). Also saw E60 M5 front brake swap, this looks temping
If after all that is done (realistically this is 1-2 years process), then I'll consider hybrid turbos but also do the SSP upgrades at the same time (900 lb/ft clutches, oil cooler upgrade and basket), upgraded fueling and then aim for 600 WHP, but I'm not sure how viable that is without at least E30 / water injection / meth? I think you need to run at least 25+ PSI, might then want to swap out the pistons if you're going to all that trouble. Then we're talking big money. I still have 2 balcony extension conversions, a garden and a kitchen to complete. I won't be allowed until it's all done
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
Ken said V8 maps are leaps ahead so you should definitely give those a go.willgill wrote: ↑Tue Dec 05, 2017 4:36 pm I've got most of the parts on the list and I didn't get anywhere near those figures (401hp), however, I'll be very interested to see how you get on I'm still waiting for my new turbos to turn up.... can't even remember how many months ago I ordered them
I've not tried the new v8 beta map but I can't see it making a huge difference.
The OTS map will be very safe, but when you get a custom one done he can push the car harder, but still be within acceptable ranges. It allows Ken to extract more once he knows the car and any weaknesses he picks up. As he has the same car, and has built many n54's in the past, he's really the leading expert on this (imho).
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
Yes, I can't get any E85, but there are places selling fuel similar to this (for a bit of fun)R.E92 wrote: ↑Tue Dec 05, 2017 4:46 pm 400whp is a decent goal and should be easily achievable on 93 octane, I'd be aiming higher if using 102 octane (unless you mean RON).
There's a lot of mods there but only the downpipes and intercooler will give you more power. I'd be tempted to upgrade to some Pure turbos since you are going to all the effort of doing that.
http://www.acs.total.com/en/racing/raci ... 02-en.html
Regular pump gas will be your usual 98 or 100 RON.
Apparently they are also working on switchable maps (within MHD) like the JB4. Don't know how that's possible though, as it's a flash, not a piggyback, I didn't ask for anymore info - guess we'll find out as it develops
Last edited by stuartinzg on Tue Dec 05, 2017 5:41 pm, edited 1 time in total.
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
-
- Lifer
- Posts: 11075
- Joined: Tue Feb 10, 2015 10:27 pm
35is upgrades (stage2+)
Hey Stuart,
Damn good news you can keep the car mate! Sounds like it’ll be a very sharp machine.
Damn good news you can keep the car mate! Sounds like it’ll be a very sharp machine.
M roady...OEM CSL’s, strut brace, Remus back boxes, ZHP
MR2 MK 2
E89 35i project car...mapped 365bhp, M4 stoppers & wheels, KWV3’s, H&R front ARB, M3 front arms, strut brace Eisenmann cat back race exhaust, VRSF downpipes inbound
E89 35is
G29
MR2 MK 2
E89 35i project car...mapped 365bhp, M4 stoppers & wheels, KWV3’s, H&R front ARB, M3 front arms, strut brace Eisenmann cat back race exhaust, VRSF downpipes inbound
E89 35is
G29
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
it's a hobby more than anything now. Has been fun getting more hands on. Forgot to mention that I had to go through a full recovery process after attempting a flash. I wanted to get stage 1 done before I take it to the shop, so the next map is very quick to load. I set everything up, hooked up a beefy charger, organised my old Samsung phone and began the write.
Then I got "error, cannot write to the ECU".
Tried to start the car, starter just carried on, no spark - then all the dongs and error messages popped up. I tried to reconnect to the DME, nothing - cable wasn't flashing. I thought I had bricked it already! Visions of having to send the DME off to MHD in Berlin ... joy.
Fortunately Ken told me to disconnect ground for 10 minutes and wait for it to reset itself and go into recovery mode. Then I managed to reestablish connection to the DME and restore the stock map. Car started up straight away. Phew.... I felt a bit clogged up and uncomfortable from the meals of the previous day (a lot of meat), but that process certainly freed everything right up double sharpish, I can tell you!
I have a few theories why it happened, but I was told just to replace the old Samsung with a newer tablet, so I've ordered the Amazon Fire HD 8" as it's cheap enough but can side-load Google Apps and works perfectly with MHD. I did think that it might have been Android 5.2 or the Samsung software causing issues, but I was able to restore the backup.
The other theory is when I tried to flash the battery wasn't charged enough and the DME just shut off (it needs a minimum voltage). Perhaps after I left it to charge during recovery it had enough power. It's struggling on startup when I leave it for a week (no trickle charging) and the starter motor was much faster after it had charged a bit. As it's 7 years old now it's probably past its use by date.
Still not sure though.
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- sunnydays
- Member
- Posts: 983
- Joined: Fri Sep 23, 2016 7:50 am
35is upgrades (stage2+)
This happened to me when using a galaxy s7 and the recommended kdan cable. Trickle charger was plugged in, car accessories off and not touched etc still happens. Luckily can just reflash after a minute or two though.stuartinzg wrote: ↑Tue Dec 05, 2017 5:46 pmit's a hobby more than anything now. Has been fun getting more hands on. Forgot to mention that I had to go through a full recovery process after attempting a flash. I wanted to get stage 1 done before I take it to the shop, so the next map is very quick to load. I set everything up, hooked up a beefy charger, organised my old Samsung phone and began the write.
Then I got "error, cannot write to the ECU".
Tried to start the car, starter just carried on, no spark - then all the dongs and error messages popped up. I tried to reconnect to the DME, nothing - cable wasn't flashing. I thought I had bricked it already! Visions of having to send the DME off to MHD in Berlin ... joy.
Fortunately Ken told me to disconnect ground for 10 minutes and wait for it to reset itself and go into recovery mode. Then I managed to reestablish connection to the DME and restore the stock map. Car started up straight away. Phew.... I felt a bit clogged up and uncomfortable from the meals of the previous day (a lot of meat), but that process certainly freed everything right up double sharpish, I can tell you!
I have a few theories why it happened, but I was told just to replace the old Samsung with a newer tablet, so I've ordered the Amazon Fire HD 8" as it's cheap enough but can side-load Google Apps and works perfectly with MHD. I did think that it might have been Android 5.2 or the Samsung software causing issues, but I was able to restore the backup.
The other theory is when I tried to flash the battery wasn't charged enough and the DME just shut off (it needs a minimum voltage). Perhaps after I left it to charge during recovery it had enough power. It's struggling on startup when I leave it for a week (no trickle charging) and the starter motor was much faster after it had charged a bit. As it's 7 years old now it's probably past its use by date.
Still not sure though.
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
Interesting... Wonder if it's a Samsung thing.sunnydays wrote: ↑Tue Dec 05, 2017 6:14 pmThis happened to me when using a galaxy s7 and the recommended kdan cable. Trickle charger was plugged in, car accessories off and not touched etc still happens. Luckily can just reflash after a minute or two though.stuartinzg wrote: ↑Tue Dec 05, 2017 5:46 pmit's a hobby more than anything now. Has been fun getting more hands on. Forgot to mention that I had to go through a full recovery process after attempting a flash. I wanted to get stage 1 done before I take it to the shop, so the next map is very quick to load. I set everything up, hooked up a beefy charger, organised my old Samsung phone and began the write.
Then I got "error, cannot write to the ECU".
Tried to start the car, starter just carried on, no spark - then all the dongs and error messages popped up. I tried to reconnect to the DME, nothing - cable wasn't flashing. I thought I had bricked it already! Visions of having to send the DME off to MHD in Berlin ... joy.
Fortunately Ken told me to disconnect ground for 10 minutes and wait for it to reset itself and go into recovery mode. Then I managed to reestablish connection to the DME and restore the stock map. Car started up straight away. Phew.... I felt a bit clogged up and uncomfortable from the meals of the previous day (a lot of meat), but that process certainly freed everything right up double sharpish, I can tell you!
I have a few theories why it happened, but I was told just to replace the old Samsung with a newer tablet, so I've ordered the Amazon Fire HD 8" as it's cheap enough but can side-load Google Apps and works perfectly with MHD. I did think that it might have been Android 5.2 or the Samsung software causing issues, but I was able to restore the backup.
The other theory is when I tried to flash the battery wasn't charged enough and the DME just shut off (it needs a minimum voltage). Perhaps after I left it to charge during recovery it had enough power. It's struggling on startup when I leave it for a week (no trickle charging) and the starter motor was much faster after it had charged a bit. As it's 7 years old now it's probably past its use by date.
Still not sure though.
Did you have to do the full reset process?
- Attachments
-
- IMG_20171203_102019-1392x1856.jpg (112.12 KiB) Viewed 964 times
Last edited by stuartinzg on Tue Dec 05, 2017 10:35 pm, edited 2 times in total.
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- stuartinzg
- Member
- Posts: 838
- Joined: Fri Aug 14, 2015 7:33 am
35is upgrades (stage2+)
Few pics of some bits
- Attachments
-
- IMG_20171124_200259-1856x1392.jpg (199.86 KiB) Viewed 964 times
-
- IMG-20171204-WA0021-1843x1037.jpeg (87.41 KiB) Viewed 964 times
-
- IMG_20171124_200253-1856x1392.jpg (185.24 KiB) Viewed 964 times
35iS, Black/Coral Red, 19" BBS CH-R/MPSS, Eiback Pro Springs, CoolCarbon Performance Pads, Golf T, Stubby, LED 80w halo's, X6 tips, CarPro CQuartz, Custom painted accessories
- sunnydays
- Member
- Posts: 983
- Joined: Fri Sep 23, 2016 7:50 am
35is upgrades (stage2+)
Yep thats the same error I get even when map switching. After map switching it gives the retry option which takes 2 minutes and works.stuartinzg wrote: ↑Tue Dec 05, 2017 10:26 pmInteresting... Wonder if it's a Samsung thing.sunnydays wrote: ↑Tue Dec 05, 2017 6:14 pmThis happened to me when using a galaxy s7 and the recommended kdan cable. Trickle charger was plugged in, car accessories off and not touched etc still happens. Luckily can just reflash after a minute or two though.stuartinzg wrote: ↑Tue Dec 05, 2017 5:46 pm
it's a hobby more than anything now. Has been fun getting more hands on. Forgot to mention that I had to go through a full recovery process after attempting a flash. I wanted to get stage 1 done before I take it to the shop, so the next map is very quick to load. I set everything up, hooked up a beefy charger, organised my old Samsung phone and began the write.
Then I got "error, cannot write to the ECU".
Tried to start the car, starter just carried on, no spark - then all the dongs and error messages popped up. I tried to reconnect to the DME, nothing - cable wasn't flashing. I thought I had bricked it already! Visions of having to send the DME off to MHD in Berlin ... joy.
Fortunately Ken told me to disconnect ground for 10 minutes and wait for it to reset itself and go into recovery mode. Then I managed to reestablish connection to the DME and restore the stock map. Car started up straight away. Phew.... I felt a bit clogged up and uncomfortable from the meals of the previous day (a lot of meat), but that process certainly freed everything right up double sharpish, I can tell you!
I have a few theories why it happened, but I was told just to replace the old Samsung with a newer tablet, so I've ordered the Amazon Fire HD 8" as it's cheap enough but can side-load Google Apps and works perfectly with MHD. I did think that it might have been Android 5.2 or the Samsung software causing issues, but I was able to restore the backup.
The other theory is when I tried to flash the battery wasn't charged enough and the DME just shut off (it needs a minimum voltage). Perhaps after I left it to charge during recovery it had enough power. It's struggling on startup when I leave it for a week (no trickle charging) and the starter motor was much faster after it had charged a bit. As it's 7 years old now it's probably past its use by date.
Still not sure though.
Did you have to do the full reset process?
Edit: Also I have a 7 inch tablet mounted (removeable) and obd cable routed through for MHD monitoring. I can provide pics if you want to see, how do you plan to mount your tablet?
And what does the 02 sensor do? I have the vrsf catless dps on the way but mhd hides the CEL and it will pass emissions anyway
- R.E92
- Senior Member
- Posts: 1644
- Joined: Wed Dec 04, 2013 10:10 am
35is upgrades (stage2+)
Room full of toys. You need to get them wrapped and put under the tree ready for the big day
They are probably going to make a logic change and have two different timing and load target tables which can be toggled between in the ROM. You would program a high power map and a low power map into the tables then have some sort of switching done by an input into the ECU like the "sport mode" selection. Similar to how BMW already do it in cars like the M5.
There is also the possibility of real time map changes. I think the ECUs in our cars have a ROM chip and a RAM chip. You can edit the RAM memory addresses directly so you can make changes instantly but the problem is the RAM will be cleared when the car powers down so the only way to make them permanent is to flash the ROM.
Normally I'd say the reason for the failed write was down to voltages like you said. If it drops below 11v(i think it's 11, not sure) then the DME will go to sleep and the write will fail. I would be cautious about using any old charger for a write, most car programming experts will recommend a proper power supply (like the Schumacher INC 700A) which can maintain a stable voltage. You may be better without any charger than with a bad one that could cause fluctuations in the voltage.
It's also possible that Samsung has some built-in power saving code that causes the MHD app to stop working correctly. I know other apps have issues with OEMs applying power saving tools into their custom android distributions.
Another thing that can cause the ECU to sleep is opening and closing the door after the ignition button is pressed. The car will automatically send the modules to sleep if it thinks the driver has left the car, even with the ignition switched on.
There's two ways of doing that;stuartinzg wrote: ↑Tue Dec 05, 2017 5:25 pmYes, I can't get any E85, but there are places selling fuel similar to this (for a bit of fun)R.E92 wrote: ↑Tue Dec 05, 2017 4:46 pm 400whp is a decent goal and should be easily achievable on 93 octane, I'd be aiming higher if using 102 octane (unless you mean RON).
There's a lot of mods there but only the downpipes and intercooler will give you more power. I'd be tempted to upgrade to some Pure turbos since you are going to all the effort of doing that.
http://www.acs.total.com/en/racing/raci ... 02-en.html
Regular pump gas will be your usual 98 or 100 RON.
Apparently they are also working on switchable maps (within MHD) like the JB4. Don't know how that's possible though, as it's a flash, not a piggyback, I didn't ask for anymore info - guess we'll find out as it develops
They are probably going to make a logic change and have two different timing and load target tables which can be toggled between in the ROM. You would program a high power map and a low power map into the tables then have some sort of switching done by an input into the ECU like the "sport mode" selection. Similar to how BMW already do it in cars like the M5.
There is also the possibility of real time map changes. I think the ECUs in our cars have a ROM chip and a RAM chip. You can edit the RAM memory addresses directly so you can make changes instantly but the problem is the RAM will be cleared when the car powers down so the only way to make them permanent is to flash the ROM.
Just goes to show how robust MHD is. You really can't go wrong with it.stuartinzg wrote: ↑Tue Dec 05, 2017 5:46 pm it's a hobby more than anything now. Has been fun getting more hands on. Forgot to mention that I had to go through a full recovery process after attempting a flash. I wanted to get stage 1 done before I take it to the shop, so the next map is very quick to load. I set everything up, hooked up a beefy charger, organised my old Samsung phone and began the write.
Then I got "error, cannot write to the ECU".
Tried to start the car, starter just carried on, no spark - then all the dongs and error messages popped up. I tried to reconnect to the DME, nothing - cable wasn't flashing. I thought I had bricked it already! Visions of having to send the DME off to MHD in Berlin ... joy.
Fortunately Ken told me to disconnect ground for 10 minutes and wait for it to reset itself and go into recovery mode. Then I managed to reestablish connection to the DME and restore the stock map. Car started up straight away. Phew.... I felt a bit clogged up and uncomfortable from the meals of the previous day (a lot of meat), but that process certainly freed everything right up double sharpish, I can tell you!
I have a few theories why it happened, but I was told just to replace the old Samsung with a newer tablet, so I've ordered the Amazon Fire HD 8" as it's cheap enough but can side-load Google Apps and works perfectly with MHD. I did think that it might have been Android 5.2 or the Samsung software causing issues, but I was able to restore the backup.
The other theory is when I tried to flash the battery wasn't charged enough and the DME just shut off (it needs a minimum voltage). Perhaps after I left it to charge during recovery it had enough power. It's struggling on startup when I leave it for a week (no trickle charging) and the starter motor was much faster after it had charged a bit. As it's 7 years old now it's probably past its use by date.
Still not sure though.
Normally I'd say the reason for the failed write was down to voltages like you said. If it drops below 11v(i think it's 11, not sure) then the DME will go to sleep and the write will fail. I would be cautious about using any old charger for a write, most car programming experts will recommend a proper power supply (like the Schumacher INC 700A) which can maintain a stable voltage. You may be better without any charger than with a bad one that could cause fluctuations in the voltage.
It's also possible that Samsung has some built-in power saving code that causes the MHD app to stop working correctly. I know other apps have issues with OEMs applying power saving tools into their custom android distributions.
Another thing that can cause the ECU to sleep is opening and closing the door after the ignition button is pressed. The car will automatically send the modules to sleep if it thinks the driver has left the car, even with the ignition switched on.