m20b20 Miller maf?

[montenegrian]

Hello,
I bought Miller MAF gen 3 few months ago without war chip. Before I bought it I asked Miller performance does it work on m20b20 engine with motronic 1.3 and 381 ecu that I have.They said that it does work so I ordered it.
So It turns out that id doesn't work! Everything was installed correctly 100% and car did work and now also works perfectly on stock AFM, but on MAF idle is perfect and on half throttle it pulls fine but on full throttle doesn't want to pull, I can upload videos to youtube.
I tried 380 ecu and m20b25 injectors but same story. I think that ecu map is not correct and that's why it doesn't works like it should.
Did anyone else put Miller MAF on m20b20

[reggid]

it works but the tune is for a non b20 obviously so thats why it is a pile of ... at WOT. needs the WAR to customize the tune

[Speedtouch]

Indeed, the map is probably intended for use with the M20B25.

[Cloggy Saint]

Unrelated to the topic, but I just had a look at the Miller website and they claim 15-30 bhp increase with their MAF. Is this accurate, it sounds like a bold claim?

[Brianmoooore]

Totally accurate IF your existing AFM is completely shot and messing up the A/F ratio. Otherwise, pretty much B/S. The main advantage of a MAF over a AFM is improved throttle response

[Cloggy Saint]

So you first need to lose the horses in order to get them back?

[HJ1981]

Totally accurate IF your existing AFM is completely shot and messing up the A/F ratio. Otherwise, pretty much B/S. The main advantage of a MAF over a AFM is improved throttle response

I do not mean to bash on this, but this is not always the case.

The factory AFM is restrictive, the question is by allowing a MAF installed (free flowing air) just how much more power will be gained? On my older 944 turbo, MAF swaps (which included a chip) yielded up to 50-70hp, mainly due to being a turbocharged car, but several dyno runs from several tuners shows the best "bang for your buck" on that car.

Since the M20 is NA, the principal is still the same, meaning the more air you can shove into the engine, the bigger the bang (assuming you have the same fuel).

So, the main advantage of a MAF is to remove the restrictions in the AFM actually, being a NA engine the TR will be noticeably improved. On a stock car, id guess maybe 5hp increase or so. However, if you combine a MAF with a mild cam and a properly tuned chip one should see a lot more gains (still guessing maybe 20-30 hp depending on the condition of the engine and chip tuning).

The software tuner i go to lives outside of Munich and worked with BMW developing the v8 engines in the 8 series, his son is also a software engineer at BMW and he was able to "fine tune" my current E82 125i software with results (last tune i saw 250hp on the dyno, after their tweaks i saw 267hp). I was going to ask them about MAF swapping on the M20B25 being worth it or not, but we are on holidays ATM.

What he did assure me before Christmas, is that they have been tuning M20s for a while, and are familiar with tuning for Schrick Cams, 2.7, 2.8 and all the way up to 3.1L stroker kits.

Since the MAF on the M20 is debatable (some people on forums showed no increase, yet other swear by them) i will be ignoring it completely till i ask the gentleman in Munch about them, since i also came across threads where people swapped MAFs from E36 models and re-tuned their chip.

[reggid]

the AFM is really only a slight restriction on a stock m20 or very mildly modified engine. there are no cheap and easy big gains on the m20b25 its the nett sum of a series of modification that are required to move forward with big power gains overall

[HJ1981]

the AFM is really only a slight restriction on a stock m20 or very mildly modified engine. there are no cheap and easy big gains on the m20b25 its the nett sum of a series of modification that are required to move forward with big power gains overall

You are maybe correct, hence why there are debates if a MAF is really needed on the M20B25 at all or not. Hence why i am ignoring it till i speak to someone who actually works on BMW electronics and coding to find out if there really are advantages to it or not.

[reggid]

A MAF is definitely better than AFM and worth doing if done correctly. however the implementation of most MAF swaps including the Miller in conjunction with the stock motronic is questionable

[steve_k]

to me personally if i was going to lay out the full cost of the miller maf & war chip & mapping i would rather pay the extra & go for full standalone & run alpha N.

[reggid]

standalone is better but you wouldn't run on alpha-N unless you had ITB

[HJ1981]

A MAF is definitely better than AFM and worth doing if done correctly. however the implementation of most MAF swaps including the Miller in conjunction with the stock motronic is questionable

As long as the chip is programmed correctly as you stated, it should be fine. As i said, it was a very common thing to do swapping from AFM to MAF in the porsche 944 turbo tuning circle. Some tuners were not good with chip tuning and others were spot on.

to me personally if i was going to lay out the full cost of the miller maf & war chip & mapping i would rather pay the extra & go for full standalone & run alpha N.

Agreed, but running a standalone is not going to be TÜV legal in Germany, also not everyone knows what they are doing and it can be very expensive to get the tune right. You probably need to rent a dyno for 2 hours and do several runs to get the AFR correct as well as the timing.

standalone is better but you wouldn't run on alpha-N unless you had ITB

Both are surprisingly legal in local yountimer racing for the E30, increasing displacement is not allowed, but going standalone and cams are (so are ITBs), hence why you see some 80s 911 (non turbos) with ITBS , Cams and standalone running 50+hp more than stock flying around Nürburgring.