maf sensor

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maf sensor

Postby thumper » Sat Oct 17, 2020 8:49 pm

I looked through the forums and didn't see much on maf sensors. I have been trying to figure out what is wrong with truck since I was able to get back to it after surgery and it doesn't make sense. Replaced fuel pump again (Edelbock external), installed new relay, circuit breaker and reset the ecu. Starts and idles without the maf sensor plugged in but as soon as I plug the maf sensor in it dies. Also while it's idling I push on the throttle just a little bit and it kills it. What am I missing here? 95 pickup 2.3l
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Re: maf sensor

Postby Buster28 » Sun Oct 18, 2020 1:11 pm

The MAF is the Mass Air Flow sensor
The MAP is the Manifold Absolute Pressure sensor

I am looking a 95 2.3L engine schematic and I see the MAP sensor connection to the ECM but there is no MAF sensor. Does your engine have both a MAP and MAF sensor?
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Re: maf sensor

Postby Tentin » Sun Oct 18, 2020 3:29 pm

Buster28 wrote:Does your engine have both a MAP and MAF sensor?


I know on my 95 pickup it has both a MAP and a MAF sensor. And I have the opposite behavior for what its worth, if I unplug the MAF it will hesitate and die.
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Re: maf sensor

Postby Buster28 » Mon Oct 19, 2020 4:30 am

So I just figured out that the schematic I am looking at is for a 2.3L carburetor engine and the 95 2WD pickup with 2.3L was upgraded to a fuel injected engine.

At startup, the MAP measures the barometric pressure so the initial air/fuel ratio is calculated correctly for the elevation of the truck. The MAF is measuring the airflow into the engine so the ECM can adjust the fuel injector duration to produce the correct air/fuel ratio.

There is very little air flow into the engine at idle so the engine will start with the MAF disconnected, but as soon as the throttle is opened there is too much air for the amount of fuel being delivered so the engine stalls.
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