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Thread: Map sensors and airflow meters.

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    Default Map sensors and airflow meters.

    I had a freind of my sons bring his heavly worked EB 5.0 Ford today to look at some problems that Ford and a few performance tunning shops cannot diagnose.

    Now i belive ive found most of the problems and until i get some parts we wont know for sure.

    Whilst under the bonnet i noticed something really strange.

    I noticed it runs of an airflow meter, fair enough.

    But on the firewall is a MAP sensor, its electricaly plugged in but the vacuum line is not connected, there are no visable points on the intake to plug a hose into to operate it.

    The puzzleing part is ive never seen a car run a airflow meter and a MAP sensor.

    The car is factory V8.

    Did Ford release these cars with MAP sensors even though they dont work or is it supposed to be connected?

    How could the car run with both airflow meters and a map sensor?

    Its got me baffled!



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    Senior Member hillbilly's Avatar
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    I admittedly know nothing about these Fords

    but are you sure its not a Idle up sensor for the air conditioning?

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    No its definitly not an idle up mate, thats the Idle speed control motor.

    The six's were fitted with a MAP sensor to read manifold pressures and run it back to the ecu for the air/fuel mix.

    The V8's were fitted with an airflow meter near the air cleaner to register the amount of air entering the manifold and also run the readings back to the ecu for the air/fuel mix adjustments.

    Its 2 diffrent ways of doing the same thing.

    Now why on earth a MAP sensor is fitted on the firewall, plugs connected but not the vacuum hose and a airlow meter connected next to the air cleaner?

    I know it runs off the airflow meter because if i disconnect it while its idleing it runs like a dog.

    I cannot for the life of me work out why a electricaly connected MAP sensor sits with no vacuum line connected on the firewall....

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    Senior Member Dave001's Avatar
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    The LS1's run both a MAP and a MAF.

    I've had a few 304-355 holden V8's show up that have been tuned on the TPS, instead of the MAP, sounds like that's what the Ford may have, if the MAP is disconected.
    I always connect the MAP back up, and tune with it, and just set a zero idle map, but most of my stuff is big solid/roller cam, hi rise single plain manifolds, they always have bugger all manifold vacuum, makes it fun to tune.

    Dave

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    Quote Originally Posted by Dave001 View Post
    The LS1's run both a MAP and a MAF.

    I've had a few 304-355 holden V8's show up that have been tuned on the TPS, instead of the MAP, sounds like that's what the Ford may have, if the MAP is disconected.
    I always connect the MAP back up, and tune with it, and just set a zero idle map, but most of my stuff is big solid/roller cam, hi rise single plain manifolds, they always have bugger all manifold vacuum, makes it fun to tune.

    Dave
    It sounds a little like this one.

    After market high lift roller cam, heaps of compression and bugger all manifold vacuum.

    Im going to play with a aftermarket piggy back ECU to see if i can settle the mixes a little, shes running bigger injecters and possibly a little too much fuel pressure for what she needs.

    But still trying to work out why Ford would even bother fitting a MAP sensor connected to nothing.

    A simple way of settling their ECU's by having it connected?

    Maybe i should try disconnecting it as an experiment next week and see what happens to the fuel curves.

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    Ok worked it out today.

    The Ford v8's run with the standard airflow meters.

    The map sensor is disconnected via the vacuum line so that it can be used to control the air mix due to outside air pressure variations.

    The map sensor measures outside air pressure, the ecu takes this into account when measuring air flow via the air flow meters.

    There you go, learn something new every day. LOL

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    Quote Originally Posted by Godzilla View Post
    Ok worked it out today.

    The Ford v8's run with the standard airflow meters.

    The map sensor is disconnected via the vacuum line so that it can be used to control the air mix due to outside air pressure variations.

    The map sensor measures outside air pressure, the ecu takes this into account when measuring air flow via the air flow meters.

    There you go, learn something new every day. LOL
    i was jsut baout to reply with that answer lol

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