map sensor testing
01-12-2013, 03:23 PM
#1
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Join Date: Dec 2012
Location: Florida
Posts: 47
map sensor testing
Anyone have any steps for testing a map sensor? With everything connected on the engine what volts am I looking for from which wires. I searched and saw the post about the problems with the connector and I would like to back probe the wires so I can see how my connector stacks up. The clip is broken off of it just like so many others so i want to see what's going on. Thanks.
01-12-2013, 03:56 PM
#2
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Location: Hell was full so they sent me to NJ
Posts: 70,648
Re: map sensor testing
Get a pigtail and fix the connector. No sense at all leaving a broken clip on there.
The PCM supplies 5.0V on the gray wire (measure voltage gray to black wire). The green wire is the signal wire (measure voltage green to black wire).
Key on, engine off you are measuring the local barometric pressure. At sea level you would see (depends on the weather) about 4.9V. Start engine, with a stock cam pulling about 20"Hg vacuum (~10"Hg MAP), you would see about 1.3V. If you have a hand vacuum pump, hook it up to the part of the sensor that goes into the manifold, and use this table:
kPA - "Hg - Volts
10 - 3.0 - 0.3
20 - 5.9 - 0.6
30 - 8.9 - 1.1
40 - 11.8 - 1.7
50 - 14.8 - 2.2
60 - 17.8 - 2.7
70 - 20.7 - 3.3
80 - 23.7 - 3.8
90 - 26.6 - 4.4
100 - 29.6 - 4.9
The PCM supplies 5.0V on the gray wire (measure voltage gray to black wire). The green wire is the signal wire (measure voltage green to black wire).
Key on, engine off you are measuring the local barometric pressure. At sea level you would see (depends on the weather) about 4.9V. Start engine, with a stock cam pulling about 20"Hg vacuum (~10"Hg MAP), you would see about 1.3V. If you have a hand vacuum pump, hook it up to the part of the sensor that goes into the manifold, and use this table:
kPA - "Hg - Volts
10 - 3.0 - 0.3
20 - 5.9 - 0.6
30 - 8.9 - 1.1
40 - 11.8 - 1.7
50 - 14.8 - 2.2
60 - 17.8 - 2.7
70 - 20.7 - 3.3
80 - 23.7 - 3.8
90 - 26.6 - 4.4
100 - 29.6 - 4.9
01-12-2013, 03:56 PM
#3
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Join Date: Jul 2010
Location: Born on the Florida West Coast, now where can I retire?
Posts: 1,505
Re: map sensor testing
Terminals:
A (black)=5vdc reference
B (green)=variable voltage sensor output (0-5vdc)
C (gray)=Ground
Here are sample differential pressure values for the output:
0v = 10 kPa
1v = 29 kPa
2v = 46 kPa
3v = 67 kPa
4v = 85 kPa
5v = 104 kPa
oops Fred beat me to it
For what it's worth, my list is actual measurements and so may be off a bit from the theoretical/design values
A (black)=5vdc reference
B (green)=variable voltage sensor output (0-5vdc)
C (gray)=Ground
Here are sample differential pressure values for the output:
0v = 10 kPa
1v = 29 kPa
2v = 46 kPa
3v = 67 kPa
4v = 85 kPa
5v = 104 kPa
oops Fred beat me to it
For what it's worth, my list is actual measurements and so may be off a bit from the theoretical/design values
Last edited by GaryDoug; 01-12-2013 at 04:01 PM.
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