MAF Conversion V5.2 - Things Are Looking Up!

[bmwman91]

I know I know, this is one of those things that seems like it will never become available, and yet it will never go away.  However, thanks to some correspondence with Bosch the converter has been bumped to version 5.2 due to some re-mapping.

Mildly-Related Content
First, my odd check engine light mystery seems to have gone away.  Not that anyone else really cares, but I am happy because now I may not need to replace my WBO2 sensor.  Talk about an odd issue.  The fault code was always 1222 (bad EGO sensor), and it came on when:
- Car started cold and I hit the main road.  After ~10 seconds at constant speed, CEL popped up.  Letting off the throttle, or flooring it made it go away.  It kept coming on until it warmed up enough.  Mileage was super crappy until CEL stopped coming on.
- Any time I rev the motor over 4500RPM it came on as soon as I let off the throttle.  Blipping throttle made CEL go away.  The car jerked a little as I came back on to part-throttle before the light went away.
- If I drove the car really hard it came on and stayed on.  The clue there was the LC-1 tossing a Sensor Over-Heated error at me.  Lean running suspicions arose...

So, if you experience these issues, and nothing seems to help, your AFM may be pooping out.

I replaced every vacuum hose on the motor because of this, but to no avail.  I was pretty stumped, and about to resign myself to buying a new LSU4.2 EGO sensor.

Related Content
Then I got some "official" data for the MAF sensor, and it turns out that my previous (experimentally determined) curves were ~5% leaner than the Bosch data would have made them.  This is more than enough to cause leaning issues.

In a couple hours I will be hooking up my custom data logger and going out for a few runs after traffic subsides.  In the morning, the second critical test will be executed: highway mileage.  I had at one point tried artificially enriching the mixture to solve the issues around 2500RPM which helped, but dropped my mileage.  So far, the power band in there seems a little better and my mileage needle seems to be good still.

So, we shall see.  Damn, I am the world's biggest MAF conversion tease (sorry guys).

Next Steps, Pending Logging
The next hurdle is figuring out the best way to get the MAF to fit on customers' cars cheaply and PROPERLY.  I am torn between two options.
1) The first is machining copies of the custom adapter I currently have that fits in the stock air box top (which you need to chop up a little).
2) The second is having tooling made for a thermoformed plastic replacement air box top.  Thermoforming is so unbelievably cheap when it comes to tooling (compared to injection molding anyway) thanks to my GF working in the industry and having connections in China.  I just need to see about the availability of high-temp plastics and the cost of this relatively large/deep tool.  I still need to devise a way to securely attach the velocity stack, but at least customers won't have to hack up their air box (only an issue at smog check time).

Of course, those who wish to use an open element filter don't need to worry about this, but without a heat shield they are going to lose power.

Last Bits
As far as the wiring harnesses, I need a little help.  I got the VW part numbers for all the connector bodies and pins from someone who is no longer an active member here.  It turns out that the terminals that go in the body were not the proper ones.  I got them to work, but I wouldn't sell something like it.  Does anyone know which terminals go with VW connector body 1J0-973-775-A?  Thanks.

The price for the converter and hardware is targeted at $200 (NOT including a MAF sensor). This may change depending on the availability of parts and wiring harness labor costs, but I think it is reasonable.  The MAF sensor is maybe $150 new, and http://www.car-part.com has them for sale anywhere from $50 to $300 used.

I AM working on sourcing an M44 MAF, but finding BMW connector bodies is proving to be a real pain.  That is the big hold-back with the M44 MAF right now.  Anyone have some tips?

[D. Clay]

Is this it?



Do you need the part numbers for the pins and sockets or do they come with this stuff?

[bmwman91]

The connectors come as the outer plastic housing, metal crimp-terminals, and some thing labeled as a seal which I found has nothing to do with it (looks like the 90degree thing in the first pic and has a mostly identical PN).  The body in the 2nd pic is the one the MAF uses, and I am looking for the terminal PN's.  The ones I was told to use were N-906-845-05 and didn't seem to fit properly (although I got them to work).

Is the car you took pics from a 2001+ VW/Audi with the 1.8L motor?

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OK, I CADed up a quick & dirty prototype showing what I would hope to make form thermoformed plastic.  Being able to bolt the MAF to the air box would be pretty nice, as opposed to having the flanges just hanging there if it were used on the stock air box.







I also just got back from data logging.  Give me ~20mins to process it and get graphs up.

[bmwman91]

OK, data logs.

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This first one is the OLD one with the V5.1 maps.  It spikes lean around 2800RPM up to an AFR of 17.8.  The AFR for the rest of it is plateaued at 15 and ~14.  Not great.


Enter the new one.  The spike hits about 16.2, which is actually almost exactly the same as the AFR spike from when I dynoed my car with the stock AFM in it.  Now, the 2 flat spots are down to 13 and 12, which is a hell of a lot better for WOT performance.


So, it seems that I am FINALLY close on the tuning part.  I am just waiting on some correspondence regarding the original AFM to double check some stuff on that map, and yeah I think we are close here.

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Again though, this thing MUST pass the highway mileage test.  Since I have not reset the ECU, I bet it will be a couple hundred more miles until it has fully adapted to the sensor not trying to run it lean.  Maybe I will unplug the battery tomorrow morning to reset the ECU, although I hate reprogramming my radio!  The way gas prices in the US are going, mileage is important.  Then again, our friends in Europe have been paying like 3 times as much for decades, and they still mod cars!  I guess us Yankees will have to get used to it.

[bmwman91]

Oh and response time has been cut in half, as well as removing a component from the board.  There is no longer an "Mdot Filtered" category since the filtering is now handled in some software I wrote.

I also suspect that my WBO2 sensor needs replacing anyway.  There was a LOT more noise in the signal than there used to be.  I guess cooking it for 2 months didn't help it any. :p

[bmwman91]

Update

I just received some data for the stock M42 AFM.  I am leaving work early to go see some college buddies and I will swing by my house to pick up the USB stick with the project files to see how this compares.  My initial impressions are that I was damn close on the AFM output.  This may be the final piece of the puzzle for fine-tuning it.

This will allow me to put a good 200 miles on the car, so the Motronic can set new Long-Term Fuel Trim corrections for the new sensor mapping.  I just filled the car up last night, so I'll see how my mileage looks Sunday.

[D. Clay]

It was from a forum for the Skoda which is some kind of VW/Audi. The thread was about them being prone to breaking from plugging/unplugging them. I like the MSD connectors as they are readily available and you can buy new pins, special crimping pliers, seals, and a special tool to take them apart - a lot handier than poking around with the little screwdrivers.
http://www.jegs.com/i/MSD/121/81735/10002/-1?CT=999

[bmwman91]

Yeah I use the MSD/GM WeatherPac connectors for everything else.  It is the OEM Bosch stuff that kills me, but there is no other way to hook the MAF up!

[bmwman91]

I put on a good 350 miles this weekend and filled it up again.  My mileage has stayed the same...28.6 miles/gal (12.2 km/L).  This was mostly highway driving, a little heavy on the gas pedal going around 85mph (~140kmh).

So, I guess the 2 main tests have passed, I just need to finish the fine-tuning and dyno it.

[ApocolypseAutoEngineering]

willthe converter require a chip?

[bmwman91]

willthe converter require a chip?

That's the beauty of it.  This thing is 100% plug and play.  No chip, no reprogrammign the ECU, just a little wire cutting at the stock AFM connector.  This thing just gets spliced in between the MAF and AFM input to the ECU.

Now, the main points with the MAF conversion on a largely stock M42 to remember are:
-/+ Power gains will be minimal
+ Throttle response will improve a lot
+ Idle stability will improve
+ Off-Idle throttle response will improve noticeably
+ No more pricey sensors with moving parts to replace

[Cobra Jet]

So, will the original AFM be completely eliminated (and can be removed from under the hood) once your little item is available?

Will replacement sensors and/or parts be available (or a source given) if the user ever needs to replace a malfunctioning, broken or aged unit or associated parts?

Also, once this is available, will those who purchase it NEED to be running a WBO2?  I see a lot of your testing is and has been done with the use of a WBO2 sensor.  I'm wondering if a WBO2 will be a necessity, which would be another expense to think about if wanting to do this type of AFM to MAF  conversion.

Can you post up your best 5 out of 10 excursions based on full tanks of gas, which would also include data such as how many miles out of a tank and the calculated mpg you are getting?  I'm curious to see if you get better, average or worse than the 28.6 mpg you initially posted with this part in place.

I'm also curious as to how you calculated your MPG - you stated 28.6 mpg on 350 miles...

From facts/FAQ's and multiple threads I have read, the gas tank on a M42 318 is 14.5 gallons.  With that in mind, 350 miles/14.5 = 24.13 mpg...?  Is your calculation based off of some other method/formula to get your 28.6 mpg or is my calc method incorrect?

[bmwman91]

So, will the original AFM be completely eliminated (and can be removed from under the hood) once your little item is available?

Will replacement sensors and/or parts be available (or a source given) if the user ever needs to replace a malfunctioning, broken or aged unit or associated parts?

Also, once this is available, will those who purchase it NEED to be running a WBO2?  I see a lot of your testing is and has been done with the use of a WBO2 sensor.  I'm wondering if a WBO2 will be a necessity, which would be another expense to think about if wanting to do this type of AFM to MAF  conversion.

Can you post up your best 5 out of 10 excursions based on full tanks of gas, which would also include data such as how many miles out of a tank and the calculated mpg you are getting?  I'm curious to see if you get better, average or worse than the 28.6 mpg you initially posted with this part in place.

I'm also curious as to how you calculated your MPG - you stated 28.6 mpg on 350 miles...

From facts/FAQ's and multiple threads I have read, the gas tank on a M42 318 is 14.5 gallons.  With that in mind, 350 miles/14.5 = 24.13 mpg...?  Is your calculation based off of some other method/formula to get your 28.6 mpg or is my calc method incorrect?

Yup, the original AFM is physically removed.

Replacements will be readily available.  The controller I use has a minimum data retention life of 20 years, so I think it will be OK.  The MAF is an off the shelf unit available many places.

No WBO2 needed.  I just use it to tune this.  The final one will be plug & play (minus a little wire cutting).

The car has had the MAF (in various stages of tuning) for the last year and a half.  My commute-mileage is around 27mpg, and I usually pull 28-30 on the highway if I can manage to stay under 85mph.  There has been no net change in mileage in any of my various tuning stages thanks to the O2 sensor doing its job (narrow-band output sent to my ECU, wide-band to my laptop).

My mileage is calculated by dividing the trip odometer by how many gallons I put in.  I fill it at the same gas station 90% of the time.  The pump runs until it clicks off, then I hold the trigger until it stops once more and that's it.  My mileage has remained very consistent so I think this is plenty accurate.

[Cobra Jet]

The car has had the MAF (in various stages of tuning) for the last year and a half.  My commute-mileage is around 27mpg, and I usually pull 28-30 on the highway if I can manage to stay under 85mph.  There has been no net change in mileage in any of my various tuning stages thanks to the O2 sensor doing its job (narrow-band output sent to my ECU, wide-band to my laptop).

My mileage is calculated by dividing the trip odometer by how many gallons I put in.  I fill it at the same gas station 90% of the time.  The pump runs until it clicks off, then I hold the trigger until it stops once more and that's it.  My mileage has remained very consistent so I think this is plenty accurate.

Ah, ok - now I see where or how you came up w/ the 28.6 mpg...  You pumped roughly 12.23 gallons of gas, traveled 350mi and your mpg is 28.6...  gotcha!  

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One more question w/ regards to the part you are working on - has it been tested w/ all octanes of pump gas (87, 89, 91 & 93)?

[bmwman91]

Ah, ok - now I see where or how you came up w/ the 28.6 mpg...  You pumped roughly 12.23 gallons of gas, traveled 350mi and your mpg is 28.6...  gotcha!  

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One more question w/ regards to the part you are working on - has it been tested w/ all octanes of pump gas (87, 89, 91 & 93)?

I am only testing this with 91 since that is the only thing my chipped car can run.  So far, I see no reason to worry about other octane gas since this does not change fueling or ignition maps.  It tells the ECU how much air is flowing lke the stock sensor, just faster and it might allow a little more in.

Since the cars are specified to use 91 octane gas at a minimum in the hand book, I would not spend time tuning for anything less than that anyway.