MAP sensor incorrect voltage
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MAP sensor incorrect voltage
Car sat for a while tons of things were replaced and checked. Everything seems to come down to the MAP sensor seeing as the car runs with it out, but starts running horrible and barely starts with it in. A new MAP sensor was already tried. Was thinking possibly a chewed wire from animals? If so, what wire would this have to be? Other than the wire that connects directly to the three pin plug powering the MAP sensor could anything else affect it electrically?
Joined: Aug 2009
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From: Central California
Car: 92 Camaro RS
Engine: LO3
Transmission: T5
Axle/Gears: stock
Re: MAP sensor incorrect voltage
Last time my car started barely running and I got a MAP sensor code it turned out the EGR valve was stuck open. Replaced and problem solved. Worth checking on at least
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Joined: Jan 2009
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From: Howell, NJ
Car: 94 Camaro
Engine: 3.5 turbo
Transmission: Performabuilt 4l60E
Axle/Gears: Strange rear, 3.42
Re: MAP sensor incorrect voltage
I would look for a vacuum leak somewhere. Map sensor reads engine vacuum as I'm sure you are aware.
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: MAP sensor incorrect voltage
Car sat for a while tons of things were replaced and checked. Everything seems to come down to the MAP sensor seeing as the car runs with it out, but starts running horrible and barely starts with it in. A new MAP sensor was already tried. Was thinking possibly a chewed wire from animals? If so, what wire would this have to be? Other than the wire that connects directly to the three pin plug powering the MAP sensor could anything else affect it electrically?
5v reference should be a gray wire. Black sensor ground and green map signal.
to test the map signal you can do it key on engine off the reading would be based on altitude.
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Re: MAP sensor incorrect voltage
You don’t state what year/engine your working with. To see if the ecm is getting the correct map signal and 5v reference you need to test it at the map pigtail.
5v reference should be a gray wire. Black sensor ground and green map signal.
to test the map signal you can do it key on engine off the reading would be based on altitude.
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Joined: Dec 2004
Posts: 16,741
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: MAP sensor incorrect voltage
I would first check the 5v reference at the ecm. You have a 1227730 ecm. The 5v ref for the map is a grey wire pin a4.
the voltage seen bye the ecm is at pin f15 the wire you should back prove to get a 3.8-5.5v reading.the middle wire is output to the ecm. You might be fighting a bad ecm or even a fuel related issue like injectors. If they are the stock injectors I would ohm them.
the voltage seen bye the ecm is at pin f15 the wire you should back prove to get a 3.8-5.5v reading.the middle wire is output to the ecm. You might be fighting a bad ecm or even a fuel related issue like injectors. If they are the stock injectors I would ohm them.
Joined: Dec 2004
Posts: 16,741
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: MAP sensor incorrect voltage
Here is a testing procedure using a 3bar map Kpa reading.
a map reading can be seen on a scanner or tuner pro rt a great diagnostic program.
http://www.robietherobot.com/storm/mapsensor.htm
a map reading can be seen on a scanner or tuner pro rt a great diagnostic program.
http://www.robietherobot.com/storm/mapsensor.htm
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