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VW nixed a MAF on 1.8TSI 
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LQFP112 - Up with the play

Joined: Thu Apr 10, 2008 5:51 pm
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So, my brother-in-law who is a VW tech is diagnosing a 2014 Passat 1.8TSI (EA888 Gen 3) that randomly stalls and gets a "MAP Sensor Signal Implausible" code set. Has new MAP and wiring all the way to ECM. Of course, there are basically no tech bulletins out for this car, but I digress.

The reason I am posting is the first thing I noticed when helping him out is that the engine has no MAF. If the MAP is unplugged the car still runs, so it must drop back to alpha-N since it doesn't have a MAF to reference. I was under the impression that pretty much all modern ECMs use a MAF because emissions requirements are so strict that speed-density mapping just doesn't cut it, especially during startup and transients. I thought it was pretty interesting that VW is only ditching the MAF now, after so many problems with them 10+ years ago, and also that more and more people running standalone EFI are using MAF.

Comments? Anyone know if this is a general movement in the industry?

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Keith MacDonald
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Sun Jun 08, 2014 3:28 am
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LQFP144 - On Top Of The Game
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Joined: Sun Jul 18, 2010 2:35 pm
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Its all different from manufacture to manufacture. Dodge had to install a MAF on their new high power cars to get it passed emissions, VW is getting rid of maf, ford on turbo vehicles doesn't use maf, but NA uses maf. I think having all three working is the best. Hell you can have both cam and crank fail on a VW and it still start and run based off last know position, advanced stuff these days


Sat Jun 20, 2015 4:21 am
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I don't think I buy the cam+crank fail, unless there are two cam positions or some sort of compression measurement or some such.

That is interesting that they are ditching MAF, the modeling must've gotten good enough :-)

Could it be that the firmware trusts the TPS due to dual sensors and DBW and that something is wrong with the DBW throttle or pedal sensor in such a way that the ECU still believes it but the MAP doesn't match? Otherwise ECU ADC damage or conditioning circuit malfunction?

110% sure that the MAP model is correct/the same?

Let us know what you come up with.

Fred.

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