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      04-23-2023, 07:27 PM   #1
sourworm
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Question 128i to 130i GM1912 Transmission Tune

Hey everyone, just did a 3SIM upgrade yesterday and definitely feeling the gains, but would like to get the transmission tuned to match that. I've tried both batch files available for my car on bimmer labs, and both failed. (7576679A.0pa.zip, 7581875A.0pa.zip).

I used a brand new Bimmer Geeks pro cable and it successfully flashed the ecu tune, as well as my transmission back to stock (ZB 7634252) after the bimmer labs tunes failed, so my instinct is to say it's not the cable. If it was a matter of bimmergeeks vs ICOM, I feel the stock flash should have failed as well. So it seems more like a matter of finding the right file + process.

From the forums I see people have been able to make it work, but can't seem to find a good resource on how to go about it (doesn't help that most content out there is for the 328i). If the bimmer labs files aren't the way, is there a particular ZB # I should be looking for in WinKFP? Or could this have been a setup issue? As in when setting up WinKFP for the trans tune, I should import the E83 datens instead of the e89

When flashing back to stock, I tried a 130i GM1912 tune ZB 7614241 in comfort mode, which failed. Still new to this stuff so also wondering if there's a way to make a tune like that work. I feel the two questions might be related.

side note: people who have done the ecu tune, have you noticed mpg gains as well? the 130i seems to get much better highway, so in theory that should apply in this case too right? Thank you!

Last edited by sourworm; 05-15-2023 at 12:11 AM..
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      05-14-2023, 11:57 PM   #2
sourworm
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Post 128i <> 130i differences: Tuner beware

Updating this thread just to serve as a quick repo for anyone looking to do this mod themselves. So a couple things:

GA6L45R Transmission:
Made some progress on the trans tune, ZB# 7614241 (HW# 7614313) DOES work, though it failed for me before this may have been due to my WinKFP setup. I disabled all UIF boxes in the configuration tab and tune successfully flashed. The difference is slight, but the best thing is peace of mind that both the engine and trans are calibrated to the same power output.

Differences between the 128i and 130i:
The two cars are very similar, but differ in a few key spots that are key to note when considering if you wanna run the tune. I did a quick check using realoem.com comparing an N52 128i produced in 5/2010 and a 130i produced at the same time. This sheet has my findings. (Got lazy with a few of the links, but feel free to verify for yourself)

https://docs.google.com/spreadsheets...gid=2018297241

Besides the airbox and the IM of course, everything is the same. But the fuel systems are almost completely different. Fuel pump, fuel tank, fuel ventilation/filter system, and a few bits and pieces. The fuel pump control unit is the same at least, but with the pump and filtration systems being different, there's likely some downstream impacts that may pop up. Getting this matched is of course not worth the effort and money, and it doesn't seem like you could just plop in a 130i fuel pump and call it.

When I first did the install I threw in a Mishimoto intake boot since its an easy mod, but put simply it doesnt fit. For anyone that buys it, put it side by side your stock intake boot, the curves are completely off. Noticing this I started paying more attention to my fuel trims, worried that it may have even caused a lean condition due to a poor seal. I removed it, but I was still seeing fuel trims in the 8-15% range at idle, with numbers getting better at higher RPMs, which would be a classic vacuum leak symptom. I did some smoke tests, torqued everything, and still nothing. My breather hose had been replaced during the install so no leaks there. I even took it to a bmw-specialized mechanic and they didn't find anything either. So I started looking closer at the cars themselves.

To do some further testing, I decided to flash the DME back to stock (ZB 8619524) to see if the problem persisted, and it did somewhat. The car ended up settling at around 5% LTFT in Bank 1 and 3% in bank 2. I then reflashed the bimmerlabs tune, and am now sitting at 8% in bank 1 and 2, though this may climb back up based on what I'm seeing with STFT. Notably, LTFT does not get better at higher RPMs anymore, though this may just need more time to pop back up. So I'm thinking I may have a hardware problem that is being exacerbated by the tune.

The airbox is pre-MAF, so I'm skeptical that would affect LTFT. But with the fuel system having so many differences, I'm starting to think that's where the problem is. A lean condition resulting from fuel would mean not enough fuel is making it to the combustion chamber. I put in a liqui moly fuel system cleaner when I bought the car a few months back, so as far as cleaners, my bases have already been covered. My thinking is since the 128i is intentionally detuned, then detuning the fuel delivery system is one way to do that. So the 130i pump could be higher flow, and without all the filtration the 128i has. Kind of just spitballing though. At least the fuel level sensor is the same lol.

When I first flashed the tune I had a few failed transmission tunes that caused the fuel pump to prime for several minutes while the car entered recovery mode, so wondering if all that excess priming did some damage. I may have a weak fuel pump based on what I saw when I flashed back to stock, but it feels likely that I wont get it down to 0% even if I replace it.

Transmission:
Both cars share the same hardware number, but are slightly different. The 128i came with the GAS6L45R-RT4 whereas the 130i has the RT1. Not positive what the difference is exactly, but the first 3 gear ratios and the final drive are different between the two cars, with the 130i being slightly more aggressive. Same mechatronics thankfully, but different torque converters.


Overall tune thoughts:
All that being said, the power boost is slight but satisfying, definitely OEM+ feeling. I was mostly in it for the MPG gains though. With the 130i being rated at ~37MPG highway vs the 128i's 28 MPG, it felt like the mod would pay for itself (which is partially why I was paying such close attention to LTFT). Currently not seeing that, in fact I'm seeing lower MPG (~-0.7 mpg) vs. my former 22 MPG average!! If I change the fuel pump and it improves then I'll update this, but as of right now, if you're in it for MPG gains then don't do it.


Next steps:
LTFTs could of course be a lot worse than 8%, but I'd at least like to know what's going on so I'm going to keep digging into this and updating this thread as I make progress. Unlikely that O2 sensors would help since I'm skeptical that all 4 would go bad at the same time. A few things I'm thinking of trying:

1. I've been wanting the Euro Airbox, so I might pick that up. I believe some kits include the Intake Air Temp sensor that came with the Euro 330i's (130i has the same MAF as the 128i tho). But I'm wondering if using the IAT + the bimmerlabs MAF delete tune could improve LTFTs. If not then I could always just plug the old MAF in.

2. Junkyard MAF. Mine seems to be working, but as a sense check it's worth grabbing a decent looking one from the junk and see if the numbers change at all.

3. New fuel pump. As established, the system is different so it may not solve the problem entirely. Will do some more research + testing here but hey if mines already weak, then it can't hurt. First a pressure test.

4. Custom tune. I'm learning to dig more into calibration files, so I'm thinking of opening up the bimmerlabs tune and referencing it against the most up-to-date 130i and 128i factory calibrations to further understand where the differences are, and see if any improvements can be made. I'm definitely no hassmaschine though lol

Last edited by sourworm; 05-15-2023 at 12:13 AM..
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      05-31-2023, 01:32 AM   #3
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Thanks for the post, helpful stuff. I'm about to tackle this tuning this weekend along with new engine, trans and diff mounts.
The difference is that mine is a euro spec 125i, which has the 3-stage intake manifold from factory. So theoretically it will be just a software tune and it will be identical to the 130i.
I couldn't find trans tune for mine on bimmer labs, but I'm sure I'll track it down. May not need it based on the VIN.
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      06-03-2023, 04:35 AM   #4
Cbeitler12
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Quote:
Originally Posted by Nothin' Special View Post
Thanks for the post, helpful stuff. I'm about to tackle this tuning this weekend along with new engine, trans and diff mounts.
The difference is that mine is a euro spec 125i, which has the 3-stage intake manifold from factory. So theoretically it will be just a software tune and it will be identical to the 130i.
I couldn't find trans tune for mine on bimmer labs, but I'm sure I'll track it down. May not need it based on the VIN.
If you have a GM transmission then this is your thread for the correct ZB number.
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      06-05-2023, 08:47 PM   #5
sourworm
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Another quick update. My fuel pressure seems to be within spec (~72 psi) for the 128i so no longer too worried about fuel related issues. Though I canít pin down the 130i spec, I canít imagine itís all that different. So for now, fuel is being deprioritized into terms of hardware problems.

Next going to look into plugging in a different MAF, and maybe even running the maf-less tune with the euro iat and airbox to see if thereís any changes.



Also, Cbeitler12 has looked into the 130i tune and compared to the 128i->130i tune and found lots of difference. Once I get a chance hoping we can pin down what the differences are exactly and see if thereís a rationale for the way things are.
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