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So much forum confusion about alpha-n tunes vs csl tunes

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Sajk
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So much forum confusion about alpha-n tunes vs csl tunes

Post by Sajk » Thu Mar 09, 2023 6:56 am

TomK wrote: Wed Mar 08, 2023 6:42 pm
Sajk wrote: Wed Mar 08, 2023 6:02 pm See below snippet from M3Carbon1’s page.
That guys tuning reputation is poor, I wouldn't listen to a word of it.

What is the point of this thread exactly? If you don't have an e46 with a CSL airbox why are you thinking about alpha-n tunes and whether they are better/worse/same as CSL and discussing it here? :?
Education. Before people throw away their maf and use an engine management strategy bmw designed for emergency in case of maf failure the facts should be clear. I read thread after thread, not necessarily here, where people have done some bolt on upgrade and are going alpha n.

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So much forum confusion about alpha-n tunes vs csl tunes

Post by beanie » Thu Mar 09, 2023 9:18 am

The thing is, if you’re fitting a csl airbox to these cars then there’s no other option, so the discussion about whether using a MAP sensor is better or not, is irrelevant.

I’d also suggest that, for most people, a carbon airbox is not a frivolous purchase so I’d assume almost anyone who buys one will be largely aware of the possible compromises. There’s also the element of theory vs practice which I’m sure I’ve mentioned before on an airbox thread. Yes, a more exact method of measuring air volume and density would in theory, be better, however the reality is that with a decent tune, alpha-n is more than fine for both city and track driving. You’ll have more drivability issues with a worn tps or dodgy sensor than alpha-n will give you.

I also wonder if some of these drivability issues people post about, normally from M3 owners who’s cars are older and with a less sophisticated ecu, are down to general wear and tear rather than the method of mapping -eg Tired vanos/sensors etc.

Thankfully there are options to suit everyone’s taste. Don’t want to go mafless, buy an eventuri. Don’t like their filters, stay stock and take peace of mind from staying original. If you aren’t satisfied with that then you have to either spend time and money developing your own solution or move on, because other than Martyn on here and a couple on Zpost, nobody is going to be doing anything significant for these cars as their limited numbers don’t warrant the investment.
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Sajk
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So much forum confusion about alpha-n tunes vs csl tunes

Post by Sajk » Thu Mar 09, 2023 3:54 pm

Fair enough.

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So much forum confusion about alpha-n tunes vs csl tunes

Post by maupineda » Thu Mar 09, 2023 4:14 pm

I have tested three setups in my car

1. Stock, nothing else or more to be said, the car is very smooth, factory smooth LoL. Is so smooth that the car has a bit less character than what you'd like

2. Karbonius Carbon Airbox with MAF + Eventury: same as above, but with that throaty induction noise that resembles the CSL, but not at the same level, but best than most cars out there. The car retains the same character as the factory setup, that being smooth in all driving conditions, with seamless throttle transients

3. Karbonius CSL Airbox (alpha N): it does change the character of the engine, is just more aggressive in general, the throttle transients are more aggressive, and less smooth, and though that may be a mapping thing, I ran epic and Severn tunning maps and both were very similar in terms of delivery. The Severn map was better as it was customized via data logging, so is unfair to compare it to epic's as that was a canned map. However, the car would have hesitations or what I better describe as kangarooing behaviors between 2-3k rpms under mid-low load situations.

The nuances, or hiccups, with Alpha-N, are what motivated me to change to my current setup, which is MAF'd carbon box with an Eventuri, but now I sometimes miss the more aggressive nature of the CSL airbox. I am sure that a MAFless setup could be made just as smooth with enough time and money, the reality is that no one outside Siemens (not even BMW) would have access to all the hundreds of maps that need to be looked at for a seamless implementation. MAF setups play with basics (timing and fueling) and rely on the baseline maps which are factory developed, which means thousands of hours of engine dyno and road driving sessions. No one will ever match or defeat that, period.

As already said, with a CSL Airbox you will have to deal with some compromises.
Last edited by maupineda on Fri Mar 10, 2023 12:48 pm, edited 1 time in total.

Sajk
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So much forum confusion about alpha-n tunes vs csl tunes

Post by Sajk » Fri Mar 10, 2023 7:13 am

Thanks for sharing your experience with this. Myself I run just an eventuri which adds a nice intake noise. Never actually heard a carbon box except on YouTube which probably does not do it justice

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So much forum confusion about alpha-n tunes vs csl tunes

Post by Vanne » Sat Mar 11, 2023 6:38 pm

beanie wrote: Thu Mar 09, 2023 9:18 am The thing is, if you’re fitting a csl airbox to these cars then there’s no other option, so the discussion about whether using a MAP sensor is better or not, is irrelevant.
I believe Pokey has been working on something and that might not be the case anymore, hopefully he might chime in.
It's been way too long between beers with Josh.. Gotta remedy that one of these days.
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So much forum confusion about alpha-n tunes vs csl tunes

Post by pokeybritches » Sat Mar 18, 2023 10:11 am

Let me blow your mind for a minute. All Z4M MAF-based tunes still use alpha-n. The MAF sensor can't respond quickly enough to rapid changes in airflow, so the ECU momentarily reverts to alpha-n until the MAF can catch up. Unfortunately most tuners don't touch the alpha-n tables with MAF-based tunes, and I would venture to say that most aren't familiar enough with the ECU to understand what it's doing. This leads to the perception of lag with the MAF tune, but in reality it's because the tune isn't optimized. It becomes more apparent with engine modifications.

I wrote a long post about alpha-n vs MAF previously, so I won't fully rehash what I've already said. In summary, MAF is better in most cases. However, a fully optimized alpha-n tune should behave like stock. Many times sensor scaling is misunderstood or ignored, and that leads to some of the problems others have mentioned with alpha-n. I would take an MSS70 alpha-n tune over a MSS54 MAF tune on any naturally aspirated or supercharged setup, due to the MSS70's wideband sensors. While the ECU "guesses" airflow with alpha-n, the MSS70's wideband oxygen sensors will tell you what the actual mixture was. The ECU trims fuel to correct.

Martyn's info is on point. MSS70 does have a built-in baro sensor. Tunes that don't perform as well at altitude are likely suffering due to the ECU operating in a different part of the fueling map which isn't typically tuned at sea level on the dyno. I have not heard of melted pistons in a naturally aspirated S54. The S54 is very robust. You wouldn't believe some of the tunes I've come across... knock thresholds raised to the moon, 16+ deg of ignition timing beyond stock with 98RON tables copied over to 91RON, on cars that are driven hard in the Middle East. I couldn't have come up with a worse tune if I was intentionally trying to blow up an S54, yet the engine endured and still put down fantastic numbers when properly tuned.
maupineda wrote: Thu Mar 09, 2023 4:14 pm 3. Karbonius CSL Airbox (alpha N): it does change the character of the engine, is just more aggressive in general, the throttle transients are more aggressive, and less smooth, and though that may be a mapping thing, I ran epic and Severn tunning maps and both were very similar in terms of delivery. The Severn map was better as it was customized via data logging, so is unfair to compare it to epic's as that was a canned map. However, the car would have hesitations or what I better describe as kangarooing behaviors between 2-3k rpms under mid-low load situations.
The car exhibited a hiccup with both Epic's tune and my tune, which would lead me to believe it was hardware-related, since the airbox was the commonality with both tunes. Most alpha-n Z4Ms don't have hiccups, and it wasn't showing in data logs. MSS70 is sensitive to brake booster faults, and the modifications to support the carbon airboxes can cause hiccups. FWIW, the Epic canned map did cost more than the Severn custom map, and we also provided the MAF-based tune for no additional charge once the car's direction changed.
maupineda wrote: Thu Mar 09, 2023 4:14 pm I am sure that a MAFless setup could be made just as smooth with enough time and money, the reality is that no one outside Siemens (not even BMW) would have access to all the hundreds of maps that need to be looked at for a seamless implementation. MAF setups play with basics (timing and fueling) and rely on the baseline maps which are factory developed, which means thousands of hours of engine dyno and road driving sessions. No one will ever match or defeat that, period.

As already said, with a CSL Airbox you will have to deal with some compromises.
OEMs don't do nearly the performance calibration work that we're led to believe, and they are bound by emissions standards. I'm fortunate to be one of the few to acquire the official Siemens documentation on MSS70, which is very rare, over 6000 pages long and describes how the ECU works. Additionally, I have a (more common) A2L file which details the addresses of all 8000 parameters in MSS70. I don't think BMW has any one single engineer that is fully familiar with MSS70, because the parameters look like they were decided upon by committee. Some sections that should be minimally relevant are overly complex- like an engineering team was seeking job validation or something to brag about to their customer- while other very important areas are only briefly covered. These files paint an interesting story. Nonetheless, it does take a lot of time to figure out MSS70, even with all the documentation. Much of it is not documented in the way we would like.
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So much forum confusion about alpha-n tunes vs csl tunes

Post by pokeybritches » Sat Mar 18, 2023 10:42 am

Vanne wrote: Sat Mar 11, 2023 6:38 pm
beanie wrote: Thu Mar 09, 2023 9:18 am The thing is, if you’re fitting a csl airbox to these cars then there’s no other option, so the discussion about whether using a MAP sensor is better or not, is irrelevant.
I believe Pokey has been working on something and that might not be the case anymore, hopefully he might chime in.
It's been way too long between beers with Josh.. Gotta remedy that one of these days.
I was looking into it, but I don't think the ECU has the logic to use a MAP like the E46 M3 CSL. I haven't found anything in the ECU's documentation mentions it, and it only seems to be referenced in the parameter section of the ECU's file. It would be nice if it was as simple as flipping a digital switch to turn it on, but I don't think that's the case.

I could use a beer or two :rofl: When are you coming out this way??
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So much forum confusion about alpha-n tunes vs csl tunes

Post by Sajk » Sat Mar 18, 2023 1:07 pm

@pokeybritches hat's fantastic information on tye way the Z4 ecu works. Thanks for that. I at altitude of about 6k feet.. is there anyone offering good remote tuning for these things.

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So much forum confusion about alpha-n tunes vs csl tunes

Post by pokeybritches » Sat Mar 18, 2023 6:25 pm

Sajk wrote: Sat Mar 18, 2023 1:07 pm @pokeybritches hat's fantastic information on tye way the Z4 ecu works. Thanks for that. I at altitude of about 6k feet.. is there anyone offering good remote tuning for these things.
I know a guy- me :) Feel free to send me a PM.
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So much forum confusion about alpha-n tunes vs csl tunes

Post by maupineda » Sat Mar 18, 2023 8:15 pm

I can say Josh’s tunes are really good. I am in Mexico City and we have 2,400m above sea level, or almost 7900 ft. . My tune is optimized for sea level but I drove it this past week in Mexico city and the car ran perfect, i always feel the effect of elevation in the engine’s performance but that is expected at such altitude which means 24% less power 😭

@pokeybritches, interesting your thought on my issue being hardware related, the MAF based tune has totally fixed the hiccups I had, I wonder if the hardware issue was the shut off valve, or the airbox itself. The car always had a vacuum dtc but there were no leaks, though we know the seal between the two halves of the CSL airbox is far from being air tight. So It could be the shutoff solenoid valve. With the MAF, Eventuri and Karb box is really smooth and hiccups free.

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So much forum confusion about alpha-n tunes vs csl tunes

Post by Slideways » Sun Mar 19, 2023 2:41 am

maupineda wrote: Sat Mar 18, 2023 8:15 pm I can say Josh’s tunes are really good. I am in Mexico City and we have 2,400m above sea level, or almost 7900 ft. . My tune is optimized for sea level but I drove it this past week in Mexico city and the car ran perfect, i always feel the effect of elevation in the engine’s performance but that is expected at such altitude which means 24% less power 😭

@pokeybritches, interesting your thought on my issue being hardware related, the MAF based tune has totally fixed the hiccups I had, I wonder if the hardware issue was the shut off valve, or the airbox itself. The car always had a vacuum dtc but there were no leaks, though we know the seal between the two halves of the CSL airbox is far from being air tight. So It could be the shutoff solenoid valve. With the MAF, Eventuri and Karb box is really smooth and hiccups free.
At least on the CSL, a leak at the airbox will not cause a DTC. It sounds like you might have an issue with one of the vacuum lines and the MAF is compensating for a hardware issue. The ECU has the baro pressure sensor, so altitude should not be your problem. Any combustion engine will lose power at that altitude change.

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