Stock ECU MAF replacement project

[prj]

3.5" silicone couplers will fit on it.
It's around 92mm from memory.

If needed Pro-M can provide pretty much any configuration MAF though.
Also, I can map Motronic to pretty much any MAF as well, as long as it gives a 0-5V signal and reads high enough, no difference really.

The reason I used the RS4 MAF is because it is easily available, fairly cheap and reads up to 600hp (standard, without meth etc).

[prj]

Let's revive this slightly, and see what we can do for people who just have their MAF go bad.

So far my progress is as follows:
* Found a HFM5 housing that will bolt on to our cars without any mods.
* Have gathered enough knowledge and know which sensor to stick in the housing.
* Found a small uC to sit in between the HFM5 and the ECU and translate signals with 0.5 % precision, which should be plenty, as the HFM5 is specified to 2%.
* Wrote the code for this uC, to do the conversion.
* Designed parts of the surrounding board, where it will sit on.
* My friend has started work on the 6 pin stock MAF connector in CAD.
* Found the estimated cost to be around 200-220 EUR with VAT included for the finished product.

What I have the most issues with:
* Making up a nice connector that will mate to the stock MAF plug (can't buy these afaik).
* Rigging up something that can suck enough air, to put the two MAF's after another and calibrate the uC.

If I manage to overcome these two obstacles, I will be able to manufacture and sell a plug and play kit with a HFM5 MAF, to replace the stock MAF.
It will behave exactly like the stock MAF, no ECU modifications will be needed, car will drive like with a brand new stock MAF. This will fit AAN, ABY, 3B and ADU engines. Also the Porsche 968.
Because the kit will be made to exactly mimic the stock maf, it will max out exactly at the same time as the stock maf. If you want to go big power, you will still need the RS4 MAF, but with this one you will never have any problem with broken wires.

I will try to rig up a prototype without the connector and pretty casing, and if that works I can go into production with this.
The goal is to provide something that works just as well as a brand new stock MAF, but is more reliable and also cheaper.
Seeing how many people have bad MAF's, and how the price of the stock MAF is going up every year, this should be a good alternative.

[s2_wot]

Can you quantify the maximum airflow you'd expect through the MAF and I'll check out a few suitable in line fans for you.

[A80Avant]

from what i can remember, the broken wire is very rarely the issue on the stock maf.
I had never had problems with a missing wire esp. on stock turbo/even the 3071. The problem was that either the maf was getting dirty,thus didnt read right, OR the maf itself failed after use to read correctly, but the wire was there.

would the HFM5 have similar issues with oil from the PCV system for example?

[prj]

from what i can remember, the broken wire is very rarely the issue on the stock maf.
I had never had problems with a missing wire esp. on stock turbo/even the 3071. The problem was that either the maf was getting dirty,thus didnt read right, OR the maf itself failed after use to read correctly, but the wire was there.

would the HFM5 have similar issues with oil from the PCV system for example?

Well, that might be your experience... I have seen plenty of broken wires.
Also there are a lot of bad MAF's floating around, and many cars with bad MAF's.
Replacement costs 263 EUR atm, and it is only expected to get higher, or perhaps it will be NLA soon? Who knows.

As for issues - there are millions of turbo cars running on HFM5's. So this would be a question for Bosch, if anything.
Personally, I have not had any problems with the stock MAF, except that mine just quit working one day. There are many that are tired and out of calibration out of 10 years.

With the kit I would sell, a new replacement element would cost 65 EUR, IF it fails.

I mean hey, if you have a better suggestion, I'm all ears.

Can you quantify the maximum airflow you'd expect through the MAF and I'll check out a few suitable in line fans for you.

About 700 kg/hr
Needs to be adjustable as well. The plan is to put both MAF's in series and log them to death.

[s2_wot]

About 700 kg/hr
Needs to be adjustable as well. The plan is to put both MAF's in series and log them to death.

So can we agree that's about 580 m3/h @ 20 deg C?

I'll have a look tonight. I think you'd need a metre of solid duct or pipe either side to make the flow stable for measuring.

[A80Avant]

i am not saying it is not a good deal or anything. But the wire is something like a myth.

if you run a poll in this forum of how many owners have seen a Maf wire being gone on a stock setup, i doubt you get any positive answers. On the other hand, you will get plenty saying that the maf got 'tired' or completely mucked up due to blowby.

if it were me and still using motronic i would definitely go for this change, but TBH, i would immediately go for the high output RS4, even if i was using a stock setup. reason being, its a ready made MAF, you convert once the hoses to fit, and its ready for any future upgrade powerwise.

[Thuppu]

But the wire is something like a myth.

Hmm, I don't think so. Maybe it hold for 400++hp if you hit the floor ones here and then..?

[A80Avant]

Please take the time to at least read fully what i write before quoting only what suits your post...

i have said it twice: for stock S2/RS2 .... and ill add mapped as well.

My experience with little over 400hp on the 3071R again didnt have any issues, but ill leave that out, as it is one personal experience and not the rule.

this replacement is for Stock replacement, not tuned cars.

[Thuppu]

Ooh, so it was only a replacement for stock cars? To bad for them who have uprated engines...

My point was that the MAF threads can hold on a 400+hp engine if you don't use the full power much. But on the other side, it can break the first time you hit the pedal if you are unlucky. You newer know. But when your power usage is almost 100% at long periods, like on track, the chance is much greater that the threads break.

[A80Avant]

excactly
i agree with you, but for that matter, the bigger RS4 maf, solves the problem!

[prj]

Broken wires are not a myth, seen so many with my own eyes, but that is not why I am doing this.
For big power cars I have the RS4 MAF solution that has been now extensively tested and happily works to 600-700 hp.

This would be indeed so that people don't start writing off cars because new MAF costs gazillion euros... or is NLA.
It will be possible to fit on any stock or not stock car, that before used the original MAF.

Of course, it will not be able to read more, or provide better range than the original, as the idea is to exactly duplicate the original's output, but it will give the ability to have a much more durable MAF and even if anything happens to it, after a one time fee of about 200 euros, it will be possible to replace the MAF sensor for 65 euros as many times as you like. I am not going to scrape the codes off the sensors or anything stupid like that.

So the idea really is to just make something that is better than the current offering for less money than the current offering, and the deeper meaning is of course to keep as many of these old cars on the road as possible.

[A80Avant]

I don't know how many stock cars you have seen with wires gone, but all the rs2 I know about 8 from Greece and most discussions on this forum from 2004 that I first started reading, and I can say that almost all of them that had problems, was with the wire in. Sometimes wiring issues as well.

I would say that the hfm will be better of it can be more robust on those areas, and of course without doubt will be dead cheaper to replace whenever it goes bad.

Keep it up!

sent using Android

[prj]

I got some great help and ideas from Shane regarding measurements and simulating airflow.
Now I just need to finish designing the board and knock up a prototype.
Because things are still quite busy ATM, I think it is more likely to happen during winter.

[diesel des]

I have broke 3 maf wires with gt2871. Now happy on vems...