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Good Article on AFM and MAF sensors and conversions
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hdenter
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PostPosted: Thu Apr 22, 2010 9:15 pm    Post subject: Good Article on AFM and MAF sensors and conversions Reply with quote

I was watching Dogpilots thread on his new MAF conversion from GO Westy (http://www.thesamba.com/vw/forum/viewtopic.php?t=259205) and saw the reply that mentioned this company

http://splitsec.com/

When I went there, I went to their tech articles and found this one

http://splitsec.com/technotes/AFM_to_MAF_Conversion.pdf

It is about converting form AFM to MAF, but it goes into how theywork and how they are made. It's and interesting read.
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pete000
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PostPosted: Thu Apr 22, 2010 9:32 pm    Post subject: Reply with quote

Go Westy won't sell them any more unless you bring in your bus for specific tuning after installation.

I tried one and had no luck, rough cold running condition. Once the engine was all warmed up worked great. I have no idea how to tune one of those things so I sent it back.

Wish it was more plug and play...
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hdenter
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PostPosted: Thu Apr 22, 2010 10:08 pm    Post subject: Reply with quote

Check out the splitsec article, totaly goes into the tuning. They sell a programable tuner or a dashmounted adjustable on the fly one in their packages with the MAF. I was impressed with what they are doing.
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GWTWTLW
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PostPosted: Thu Apr 22, 2010 10:30 pm    Post subject: Reply with quote

pete000 wrote:
Go Westy won't sell them any more unless you bring in your bus for specific tuning after installation.

I tried one and had no luck, rough cold running condition. Once the engine was all warmed up worked great. I have no idea how to tune one of those things so I sent it back.

Wish it was more plug and play...


unless they just changed their policy, I don't believe that is true. I had them ship me mine. I also had some cold running issues that took a while to work through. They were diligent in working with me to get it working properly. In the end, I got a Tune that I am real happy with. It is still running rich at cold start but I can live with that.

I don't think the version that GW sells supports a tune on the fly. I have to have the ignition off to upload a new tune. You can view the maps in real time and make changes to them but you can't upload them to the CPU with the engine running. They may have an upgraded box though.
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jerryherb
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PostPosted: Thu Nov 16, 2017 10:07 am    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

Since i am not able to located any other info on split second MAF conversion application since 2010 im bumping this thread.

Can someone whom applied this set up successfully list the parts that need to be obtain from SS to get this running?

Is there a repository of program map files (MS DB format per DogPilot's article) that one can uploaded to these units somewhere?

Was anyone successful implementing this MAF system in a digijet and/or AC AFC application?
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Vanagon Nut
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PostPosted: Thu Nov 16, 2017 11:41 am    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

I was curious about the SS pdf. Found a working link via a BMW page:

https://splitsec.com/wp-content/uploads/technotes/TN2_AFM_to_MAF_Conversion.pdf

If no users chime in, what about searching the BMW or VW tuner pages?

That R4 software looks like it adapts the MAF to work with whatever the older engine management is? Sure looks like a painful trial and error process?
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jerryherb
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PostPosted: Thu Nov 16, 2017 9:17 pm    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

Interesting read. thanks for finding the document. Those whom have the SS MAF installed, can you share the type/size of the sensor installed and the map files with descriptions? need to know if the AFM goes from 0-5 or 5-0 volts.

If i have time i will attempt to get maps set for all vanagon gas engines once i get good unmolested AFMs and am able to "copy" their behavior to the MAF in a controlled environment and go from there. it appears the SS tech and programming has improved greatly in the last decade Smile
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ohhorob
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PostPosted: Fri Nov 17, 2017 8:26 am    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

jerryherb wrote:
Interesting read. thanks for finding the document. Those whom have the SS MAF installed, can you share the type/size of the sensor installed and the map files with descriptions? need to know if the AFM goes from 0-5 or 5-0 volts.

If i have time i will attempt to get maps set for all vanagon gas engines once i get good unmolested AFMs and am able to "copy" their behavior to the MAF in a controlled environment and go from there. it appears the SS tech and programming has improved greatly in the last decade Smile


AFM is 0 to 5v. Voltage from sensor ground (pin 6) to wiper (pin 15 on Digijet)

I have an Innovate SSI4 connected to mine, and also capture RPM, injector duty and TEMPII volts.
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PostPosted: Fri Nov 17, 2017 8:46 am    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

The graph shows 0 - 5 volts for both types. This got me to thinking though. Has anyone verified that the Vanagon ECU's are outputting 5 volts to the original air flow sensor?

If the Vanagon ECU is outputting a 5 volt reference to the ECU, then a better solution might be to us a GM type MAP sensor. You could also add a GM type IAT sensor for the other circuit.

The GM type MAP sensor has 3 wires. One is a constant +5 volt reference to the sensor from the ECU. It has a ground wire that is also supplied by the ECU usually, but not sure how important that is. The 3rd wire is the output from the MAP sensor to the ECU. MAP voltage at 0% load around 10KPa. WOT 100% load map voltage would be 5.00 volts 105 kPa.

It can't be that easy, but it would be a simple solution to replace a tired Bosch airflow sensor. Mount it, connect a vacuum hose to the manifold plenum modify the wiring and add an IAT sensor.
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PostPosted: Fri Nov 17, 2017 9:57 am    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

Quote:
Has anyone verified that the Vanagon ECU's are outputting 5 volts to the original air flow sensor?


Yes, Digijet and -fant went to the 0-5V sensor bus standard, all sensors are fed the regulated 5V from the ECU.

The ECU's 5V is fed to the AFM at AFM pin 1 and 3.

Pin 1 goes to ground via the IAT sensor as one leg of a voltage divider in the ECU (and I have never ever seen an IAT go bad in one of these AFM's, by the way).

Pin 3 goes to the board which acts as a complete variable voltage divider itself, one leg goes to ground at pin 4, while pin 2 returns a variable 0-5V signal to the ECU via the wiper.

Quote:
It has a ground wire that is also supplied by the ECU usually, but not sure how important that is.


Pretty important, I'd say, sensors are referenced to the ECU's internal ground bus and with low-V signals, small ground V offsets can really shift the signal, so it's important they all reference the same zero V. That internal bus's 0V will only be as good as the ECU's external ground points, but if there's a V offset there, at least all sensors will offset the same amount so still be accurate relative to each other.

It's also important to be sure any sensor's independent ground (like the Temp2's) is not shared with that of any loads that use real power, or the V offset the load current creates at the connection will offset the sensor's ground V.

And if you're using a WBO2 setup, ground it at the left head with the independent O2 sensor ground reference wire from the ECU, and no other connectors on that point, use the adjacent bolt hole on the head for the engine ground strap. Better yet, run a large ground strap directly from the alternator chassis to the van body because that's where the high current is that causes big V-offsets at shared ground points.

I've long thought a 1bar MAP sensor might be able to be used, I even have a VW one with IAT built in for my eventual Microsquirt conversion, but I haven't set it up to see if the return voltage curves look the same as the stock AFM.
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MarkWard
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PostPosted: Fri Nov 17, 2017 10:09 am    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

I have a running 87 collecting dust. Being an electromotive dealer, I have access to parts to try a test. We even have a chassis dyno so we can create all sorts of load conditions. The problem is finding the time to set it all up with little return.

If it worked with the stock ECU programing, an aluminum tube with a flange to take the place of the airflow sensor and a bung for an IAT sensor, you could have a simple and affordable solution for the aftermarket.

Because it would still depend on antique electronics, a complete affordable standalone solution like the MS would be a better investment of time. We sell Electromotive and even their basic system is $$$ for the average VW owner. That's why I have not gone so far as to develop a turn key solution.

Plus, no two engines are alike and a tune that works with one engine, is probably not optimized for the next one and tuning for a DIY person has a huge learning curve and really needs to be backed up by a dyno. I imagine this may have been part of GW's reset with their standalone system.
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Vanagon Nut
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PostPosted: Fri Nov 17, 2017 2:13 pm    Post subject: Re: Good Article on AFM and MAF sensors and conversions Reply with quote

Thanks for posting that. I'd long wondered about ground buss points (for lack of better term) in a given automotive wiring harness. Especially if adapting a harness from another vehicle into a Vanagon. (e.g. the Motronic harness has specific labels of 'sensor ground' etc shown in diagrams) i.e. I'd thought maybe some ground wires were shorter only due to aspects of design and manufacturing but maybe even a 3' difference in length of a ground wire might add enough resistance to affect the ECU supplied 5 Volts? Anyhow......

Neil.


tencentlife wrote:
....

Quote:
It has a ground wire that is also supplied by the ECU usually, but not sure how important that is.


Pretty important, I'd say, sensors are referenced to the ECU's internal ground bus and with low-V signals, small ground V offsets can really shift the signal, so it's important they all reference the same zero V. That internal bus's 0V will only be as good as the ECU's external ground points, but if there's a V offset there, at least all sensors will offset the same amount so still be accurate relative to each other.

It's also important to be sure any sensor's independent ground (like the Temp2's) is not shared with that of any loads that use real power, or the V offset the load current creates at the connection will offset the sensor's ground V.

And if you're using a WBO2 setup, ground it at the left head with the independent O2 sensor ground reference wire from the ECU, and no other connectors on that point, use the adjacent bolt hole on the head for the engine ground strap. Better yet, run a large ground strap directly from the alternator chassis to the van body because that's where the high current is that causes big V-offsets at shared ground points.

I've long thought a 1bar MAP sensor might be able to be used, I even have a VW one with IAT built in for my eventual Microsquirt conversion, but I haven't set it up to see if the return voltage curves look the same as the stock AFM.

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1981 VanaJetta 2.0 Westy "Jaco"

In Progress: 50 ABA Swap to '88 Westy:

http://tinyurl.com/yap5hpwt

Vanagon VAG GAS engine swap Google Group:
https://sites.google.com/site/t2t3vaggasengineswaps/home

My Air Cooled Vanagon to 15 Jetta ABA swap pages:

http://tinyurl.com/y9n4xob8
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