I just noticed that my truck has a MAF and a MAP. Do the newer ECM's use both and for what reason?

Jason

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89 Six Speed FX3 coupe
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Comp Cams Custom cam 550 lift 220/229 duration
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AFR 195 competition ported heads
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I'm betting you have a newer 99 or above truck (CK) with a Vortec V8 right?

Just like the LS1's they use both a MAF and MAP for some reason, but I don't know why.

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86 Trans Am WS6 Black with tinted windows, shaved door handles
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Yes its a 2001 Chevy Silverado with the 5300 V8. Maybe the MAP is used for load where the old MAF like on my 89 uses LV8 which is a calculated value???

Jason

 

Just a thought but are you sure there is a vaccuum line going to it? If not it might be just a baro. sensor... same identical sensor just when you don't put vaccuum to it and leave it open to atmosphere it reads barometric pressure.

 

Actually, most of your OBDII engines have both, like the 5.0, 5.7 vortecs, the 3100, 3400, 3800, 4800-5300-6000-8100 vortec engines (genIII), etc... Even the later LT1 engines had both. And there is not a Baro sensor anymore. The PCM uses the MAP sensor to take a "baro" reading when the key is on, then is used as a MAP sensor once the engine starts.

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Each have their own strong points. Done right, the MAF will supply a slightly more accurate steady state reading then the MAP. The intake tract on a MAF does some signal dampening, and prevents some reversion errors. The MAP allows for much better metering suring sudden transistions. the MAP is always prone to some (small with stock cams) reversion errors