MAF to stock airbox adapter
04-24-2009, 01:01 AM
#1
Drifting
Thread Starter
MAF to stock airbox adapter
I'm not having much luck searching 
I'm looking for the adapter that bolts to the stock airbox that changes it from rectangle to round. I'm thinking about going to a MAF setup and have been looking at the Lindsey Racing Quad M with the built-in controller. I want to keep the stock airbox - the brand new airbox assembly I ordered from Pelican arrived yesterday.
I'm up in the air about a MAF though. The PO had one installed and the car ran like crap. I fixed the hacked harness and returned everything back to stock. Now that I've got the car pretty much straight, I'm thinking about it again.
I've also been watching for threads about Megasquirt. I wouldn't mind going to MAP either.
I'm looking for the adapter that bolts to the stock airbox that changes it from rectangle to round. I'm thinking about going to a MAF setup and have been looking at the Lindsey Racing Quad M with the built-in controller. I want to keep the stock airbox - the brand new airbox assembly I ordered from Pelican arrived yesterday.
I'm up in the air about a MAF though. The PO had one installed and the car ran like crap. I fixed the hacked harness and returned everything back to stock. Now that I've got the car pretty much straight, I'm thinking about it again.
I've also been watching for threads about Megasquirt. I wouldn't mind going to MAP either.
04-24-2009, 04:39 AM
#2
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Do Vitesse still do their Stealth MAF kit? - that's what I would go for. You get the adapter as part of the kit & the car will run great straight out of the box 
I don't think John will sell you the kit without uprated injectors.
I don't think John will sell you the kit without uprated injectors.
04-24-2009, 09:01 AM
#3
Drifting
Thread Starter
I looked at the Vitesse kit, but at over $1500, it's a bit beyond my budget right now. And yes, you have to replace the injectors. The Quad-M from LR is $455 and everything is built into the MAF.
04-24-2009, 09:08 AM
#4
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Vitesse MAF is $1250 not $1500 and is a True MAF conversion. Good luck!
04-24-2009, 09:56 AM
#5
Drifting
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04-24-2009, 10:19 AM
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Larger injectors are needed because the factory injectors running at very high duty cycles.
04-24-2009, 12:47 PM
#7
Drifting
Thread Starter
The DME doesn't understand MAF and you're still translating it to data that the Motronic computer can understand - you're just doing it on a board that plugs directly into the DME. Yes, you're doing it "in the DME", but it's external to the factory computer. That's still emulation and it's still semantics.
But I'm not here to get into a pissing match with you. If I had the budget, I'd probably buy your system because I think it's the most thought out setup available for our cars using the stock computer. What I don't like is having to replace the injectors since it isn't necessary at my current power levels. I'm not out to make 300+ HP. I just want to remove an intake restriction and reduce lag without having to spend an arm and a leg to do it. Nothing more, nothing less. I'm going to be daily driving this car with the stock turbo running <1 bar of boost.
Really, all I want is the adapter for the stock airbox. I'm looking for a sub $600 solution.
But I'm not here to get into a pissing match with you. If I had the budget, I'd probably buy your system because I think it's the most thought out setup available for our cars using the stock computer. What I don't like is having to replace the injectors since it isn't necessary at my current power levels. I'm not out to make 300+ HP. I just want to remove an intake restriction and reduce lag without having to spend an arm and a leg to do it. Nothing more, nothing less. I'm going to be daily driving this car with the stock turbo running <1 bar of boost.
Really, all I want is the adapter for the stock airbox. I'm looking for a sub $600 solution.
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04-24-2009, 02:41 PM
#9
Three Wheelin'
If you're going to run at stock boost, I don't think it's worth putting in a MAF. If you're going to turn up the boost at all over stock you need a chip also, right? To be safe you'll also probably need to pay someone to tune it with that MAF, or at least make sure AFR is good.
With the Vitesse MAF you get the chip also, and can be confident that AFR will be good right out of the box. Well worth it in my opinion.
With the Vitesse MAF you get the chip also, and can be confident that AFR will be good right out of the box. Well worth it in my opinion.
04-24-2009, 02:49 PM
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The DME doesn't understand MAF and you're still translating it to data that the Motronic computer can understand - you're just doing it on a board that plugs directly into the DME. Yes, you're doing it "in the DME", but it's external to the factory computer. That's still emulation and it's still semantics.
I'm not arguing with you, however I'm correcting your FALSE statements be it the price or the way the Vitesse system works.
I understand about your budget, I'm not trying to sell you a kit.
BTW. Based on your requirements, you will be better off keeping the stock AFM and getting a better boost control system.
Best of luck!
04-24-2009, 03:05 PM
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The DME doesn't understand MAF and you're still translating it to data that the Motronic computer can understand - you're just doing it on a board that plugs directly into the DME. Yes, you're doing it "in the DME", but it's external to the factory computer. That's still emulation and it's still semantics.
Search for "transfer function" in the 944 and 944 Turbo forums.
04-24-2009, 03:15 PM
#13
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I did some searching for you:
Just to clarify few things.. Both AFM and MAF generate a 0-5v signal. The more air going through the higher the signal. The voltage generated by the AFM is not the same as the signal generated by the MAF.
Each MAF has a unique calibration, so now you have various MAF (with different calibration) generating different signals..
The DME figures out the load based on the input (0-5v) signal, and based on this signal it determines the fuel requirements as well as timing under certain conditions..
Based on the above, it's clear that the DME must be aware of the relationship between signal and load... That's where the "Transfer Function" comes into play. Each MAF with a unique calibration has a unique transfer function.. Using the correct transfer function, allows the DME to always figure out the correct LOAD, which is used for subsequent calculations..
There are different ways of adapting a MAF to a DME designed to work with AFM.
- Use a signal massager.. Well if the MAF you are using, uses a curve that is fairly close the curve of the AFM you are replacing, you might get away with it. However change injectors, then tune (with signal massager) and the voltage seen by the DME is totally different. The DME still calculates the same old LOAD as it did with the AFM. However the "actual or real" LOAD is way different than the DME is calculating. Of course you AFR is fine now, but remember, LOAD is also used to determine other values such as timing under Part Throttle. This is why some people experience hesitation or bucking when using signal massagers when adapting a MAF to their car.
- The second method of adapting a MAF is to use a chip designed to work with the particular MAF you are using. This is done by coding the correct "Transfer Function". Again the Transfer Function correlates a voltage to a LOAD value. When the MAF calibration changes, the voltage curve changes, the transfer function has to change in order to get the CORRECT LOAD. Once LOAD is determined correctly, the DME has the correct information to do its calculations.
Few things to be aware of. Both AFM and MAF has upper limits! Once the barn door inside the AFM is fully open, the AFM generates the MAX voltage it was designed for. Also, a MAF (based on its calibration) can max out and generate the highest voltage (even though you have not reached the MAX air flow going through it). So choosing the correct MAF calibration is very important to support a particular engine setup.
* In order to burn the correct MAF chip some variables must be known in advance. The MAF calibration and the size of injectors are the key. So by saying it's a 75mm MAF or so and so StageX does not give the accurate required information. With experience, we make assumptions as to which MAF was used with a particular setup...
Note: Not 2 cars are 100% identical. That's why a signal massager is nice to have to fine tune things to match your setup. The fine tuning does not and should not alter the signal in a way to affect the calculated LOAD by a large amount.
I hope this clarifies some of the issues.. And I hope I didn't confuse matters...
Please do not ask me for pricing on this board, visit the website for pricing information and/or email me directly.
Each MAF has a unique calibration, so now you have various MAF (with different calibration) generating different signals..
The DME figures out the load based on the input (0-5v) signal, and based on this signal it determines the fuel requirements as well as timing under certain conditions..
Based on the above, it's clear that the DME must be aware of the relationship between signal and load... That's where the "Transfer Function" comes into play. Each MAF with a unique calibration has a unique transfer function.. Using the correct transfer function, allows the DME to always figure out the correct LOAD, which is used for subsequent calculations..
There are different ways of adapting a MAF to a DME designed to work with AFM.
- Use a signal massager.. Well if the MAF you are using, uses a curve that is fairly close the curve of the AFM you are replacing, you might get away with it. However change injectors, then tune (with signal massager) and the voltage seen by the DME is totally different. The DME still calculates the same old LOAD as it did with the AFM. However the "actual or real" LOAD is way different than the DME is calculating. Of course you AFR is fine now, but remember, LOAD is also used to determine other values such as timing under Part Throttle. This is why some people experience hesitation or bucking when using signal massagers when adapting a MAF to their car.
- The second method of adapting a MAF is to use a chip designed to work with the particular MAF you are using. This is done by coding the correct "Transfer Function". Again the Transfer Function correlates a voltage to a LOAD value. When the MAF calibration changes, the voltage curve changes, the transfer function has to change in order to get the CORRECT LOAD. Once LOAD is determined correctly, the DME has the correct information to do its calculations.
Few things to be aware of. Both AFM and MAF has upper limits! Once the barn door inside the AFM is fully open, the AFM generates the MAX voltage it was designed for. Also, a MAF (based on its calibration) can max out and generate the highest voltage (even though you have not reached the MAX air flow going through it). So choosing the correct MAF calibration is very important to support a particular engine setup.
* In order to burn the correct MAF chip some variables must be known in advance. The MAF calibration and the size of injectors are the key. So by saying it's a 75mm MAF or so and so StageX does not give the accurate required information. With experience, we make assumptions as to which MAF was used with a particular setup...
Note: Not 2 cars are 100% identical. That's why a signal massager is nice to have to fine tune things to match your setup. The fine tuning does not and should not alter the signal in a way to affect the calculated LOAD by a large amount.
I hope this clarifies some of the issues.. And I hope I didn't confuse matters...
Please do not ask me for pricing on this board, visit the website for pricing information and/or email me directly.
Here is a quote I got from someone who has installed a MAF system onto his AFM based 911. This guy programs his own chips and is giving some pointers on programming the DME chip.
On the EPROM there's a "air flow meter transform" table that has to be redone to match the new mass air meter curve. This is the tricky part and I could never explain it in one e-mail. The response curve of the hot film meter looks a lot different from the flapper and can not be done correctly with the existing code so you really have to re-write some code to make it work well.
There's an air-temp compensation table that has to be "flattened." You don't need air-temp compensation for fuel because the fot film meter is measuring air mass flow.
The fuel tables are for fine-tuning. If the air flow meter transform function is done right, the fuel tables will not require much work to get the car running well.
Reprogramming Motronic for different injector flow-rates is a real pain, especially on the 964 and newer cars. What makes it so difficult is that Motronic uses injector pulse-width to represent load so injector pulse-width is referenced in a lot of places.
On the EPROM there's a "air flow meter transform" table that has to be redone to match the new mass air meter curve. This is the tricky part and I could never explain it in one e-mail. The response curve of the hot film meter looks a lot different from the flapper and can not be done correctly with the existing code so you really have to re-write some code to make it work well.
There's an air-temp compensation table that has to be "flattened." You don't need air-temp compensation for fuel because the fot film meter is measuring air mass flow.
The fuel tables are for fine-tuning. If the air flow meter transform function is done right, the fuel tables will not require much work to get the car running well.
Reprogramming Motronic for different injector flow-rates is a real pain, especially on the 964 and newer cars. What makes it so difficult is that Motronic uses injector pulse-width to represent load so injector pulse-width is referenced in a lot of places.
04-24-2009, 03:39 PM
#15
Drifting
Thread Starter
Much appreciated. Still looks the same to me - the chip (regardless if MAF or AFM) is doing a translation into a format that the computer can understand. Since the computer was built around a AFM setup, I still maintain that a MAF chipset is still outputting a signal that mimics an AFM within specified parameters. At this point, I think I'll wait out a MS solution and go MAP with a wideband.
Thom - if it isn't too much trouble, I'd appreciate some pictures. I've found all sorts of filter adapters that bolt to the AFM that allows the use of a conical filter. I think I can turn the adapter around and use it on the airbox. The adapters are cheap (in more ways than one, I'm sure) - starting around $10.
Thom - if it isn't too much trouble, I'd appreciate some pictures. I've found all sorts of filter adapters that bolt to the AFM that allows the use of a conical filter. I think I can turn the adapter around and use it on the airbox. The adapters are cheap (in more ways than one, I'm sure) - starting around $10.