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Old 04-11-2006, 09:12 PM   #1
djcontra
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MAP sensors

Does anyone here know how or if it's possible to install a MAP sensor on our cars to replace the MAF? The MAF seems pretty useless to me on a boosted car
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'94 Supercharged E36 325is (150,000 original km's)
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Old 04-11-2006, 09:21 PM   #2
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thats a good question, i think its very possible as long as the map sensor can bypass or somehow emulate the main function of the MAF, because our cars just wont run without them.
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Old 04-11-2006, 09:31 PM   #3
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I know next to nothing about MAP sensors work at the electrical level, but I'm thinking if they give off the same range of voltage readings as the MAF, or you could find one that was within that same range, it should all wire up. It makes more sense to monitor air intake through pressure on our cars than through flow. Then again, I could have it all wrong on how they send signals to the computer too so all of that may not work at all
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'94 Supercharged E36 325is (150,000 original km's)
Mods
-Vortech V9 G-Trim @ ~10psi w/ BOV
-Shortstack headers
-Vortech RRFPR
-255LPH Walbro fuel pump
-TEIN SS Coilovers w/ Pillowball mounts
-Keskin KT1 17x8.5 & 17x10
-Remus full catback
-Authentic Rieger Infinity I body kit
-SMT6 EMS (Untuned)

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Old 04-11-2006, 11:02 PM   #4
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i understand what your saying but how critical is that info to you? air flow is good for NA cars, but im kinda new to FI, and leaning things myself, i dont know what more you need beyond a boost gauge.
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Old 04-29-2006, 08:10 PM   #5
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Quote:
Originally Posted by djcontra
Does anyone here know how or if it's possible to install a MAP sensor on our cars to replace the MAF? The MAF seems pretty useless to me on a boosted car
Why would you think a MAF sensor is useless on a a car with FI? If it can accurately measure the mass of the air entering the motor at max boost, it will be fine. Now if you had the older AFM which was used before MAF's were common on BMW's, you would have a good reason to swich to a MAF or MAP sensor.

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Old 05-08-2006, 08:40 PM   #6
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Check this out....

http://www.idaautomotive.com/changin..._a_map_sen.htm
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Old 05-08-2006, 09:15 PM   #7
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Thanks Sly, that article is actually really useful to me as I have an SMT6 on my car as well.

Mark, can you enlighten me a bit more on how a MAF is able to accurately measure the volume of air when it can't sense air pressure? Thats why i was leaning towards using a MAP sensor instead, because I just can't comprehend that my MAF, being situated before my S/C on the non-boosted side can accurately know how much air is being boosted into my engine....im confused by the thought

thanks!
__________________

'94 Supercharged E36 325is (150,000 original km's)
Mods
-Vortech V9 G-Trim @ ~10psi w/ BOV
-Shortstack headers
-Vortech RRFPR
-255LPH Walbro fuel pump
-TEIN SS Coilovers w/ Pillowball mounts
-Keskin KT1 17x8.5 & 17x10
-Remus full catback
-Authentic Rieger Infinity I body kit
-SMT6 EMS (Untuned)

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Old 05-08-2006, 10:22 PM   #8
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Quote:
Originally Posted by djcontra
Thanks Sly, that article is actually really useful to me as I have an SMT6 on my car as well.

Mark, can you enlighten me a bit more on how a MAF is able to accurately measure the volume of air when it can't sense air pressure? Thats why i was leaning towards using a MAP sensor instead, because I just can't comprehend that my MAF, being situated before my S/C on the non-boosted side can accurately know how much air is being boosted into my engine....im confused by the thought

thanks!

Your motor's engine management system (DME) does not care about the volume of air, it wants to know the MASS of the air so it can determine how much fuel to inject. The mass does not change once it passes through the Mass Air Flow (MAF) sensor. It's not a VAF (volume of airflow ) meter!
The meter outputs a voltage that indicates how many grams/sec or Kg/hr of air is passing though it and the volume or pressure of the intake air is not relevant. Once the DME knows how many grams of air / sec is entering the motor, it injects the required amount of fuel to keep the air/fuel ratio at the target lambda value.

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