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Offline Shimy87

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MAP sensor
« on: July 14 2018, 11:30:15 AM »
My alky won't activate under boost but test button works fine. Have 5.06 volts on grey wire at MAP....green wire has .09 volts. Question is when I blow hard in tube going to map voltage on green wire dosent change....it should unless a person can't blow hard enough to make it change??
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Offline earlbrown

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Re: MAP sensor
« Reply #1 on: July 14 2018, 11:41:33 AM »
If you can blow hard enough to make it change, I have a new and exciting field of work for you!
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Offline Steve Wood

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Re: MAP sensor
« Reply #2 on: July 14 2018, 11:48:58 AM »
LOL  yeah, you need a bit more air pressure
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Offline Shimy87

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Re: MAP sensor
« Reply #3 on: July 14 2018, 11:50:44 AM »
Ha ha. Ok thanks...i didn't know.
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Offline aminga

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Re: MAP sensor
« Reply #4 on: July 14 2018, 07:43:46 PM »
It should have some voltage at atmospheric
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Offline daveismissing

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Re: MAP sensor
« Reply #5 on: July 14 2018, 08:05:57 PM »
Assuming stock 2Bar MAP

 
Manifold Pressure2 Bar
(relative sea level / absolute)
MAP Output
14.31psi / 29.01psi4.90V
14.00psi / 28.70psi4.84V
13.00psi / 27.70psi4.67V
12.00psi / 26.70psi4.50V
11.00psi / 25.70psi4.33V
10.00psi / 24.70psi4.16V
9.00psi / 23.70psi3.99V
8.00psi / 22.70psi3.82V
6.00psi / 20.70psi3.47V
4.00psi / 18.70psi3.13V
2.00psi / 16.70psi2.79V
0.00psi / 14.70psi2.45V
5.00inHg / 12.24psi2.03V
10.00inHg / 9.78psi1.61V
15.00inHg / 7.33psi1.19V
20.00inHg / 4.87psi0.77V
25.00inHg / 2.41psi0.35V
29.10inHg / 0.40psi0.02V
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Offline Steve Wood

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Re: MAP sensor
« Reply #6 on: July 14 2018, 08:16:28 PM »
he has a 3 bar sensor so give him the table for that
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Offline Shimy87

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Re: MAP sensor
« Reply #7 on: July 14 2018, 08:29:25 PM »
Worked fine....stoppe d for a beer and quit.....every thing seems in order so I'm stumped...will be calling julio....any ideas??
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Offline Steve Wood

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Re: MAP sensor
« Reply #8 on: July 14 2018, 08:38:09 PM »
I think you were on the right track to check the map output.  You did check the line from the sensor (vacuum) to make sure it is not cracked or broken?

Here's a link that shows voltages for a 3 bar  http://injector-rehab.com/shop/mapsensor.html
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Offline daveismissing

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Re: MAP sensor
« Reply #9 on: July 14 2018, 09:30:04 PM »
A 2 Bar should be around 5volts at 30 lbs, a 3bar 5v at 45lbs. Got a compressor with a regulator that turns way down?
jury rig connection to tire pressure?
EDIT ;absolute numbers so subtract 14.7
« Last Edit: July 14 2018, 10:20:25 PM by daveismissing »
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Offline good2win22

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Re: MAP sensor
« Reply #10 on: July 15 2018, 09:13:35 AM »
I used my oxy-acetelyne rig to calibrate the MAP table.  Gauge is a little easier to read at those low pressures
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Offline Shimy87

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Re: MAP sensor
« Reply #11 on: July 15 2018, 11:24:39 AM »
Thanks guys...yes line is good so I gotta figure out a way to put regulated air to it to test. My compressor regulator is shot so it's to much. Gives me a reason to replace it now I guess :icon_eyes:
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Offline earlbrown

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Re: MAP sensor
« Reply #12 on: July 15 2018, 01:32:22 PM »
Unplug the compressor and blow it down to 30psi.  Then hook it to the MAP.
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Offline Scoobum

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Re: MAP sensor
« Reply #13 on: July 15 2018, 01:50:20 PM »
Quote from: earlbrown on July 15 2018, 01:32:22 PM
Unplug the compressor and blow it down to 30psi.  Then hook it to the MAP.

Earl...didn't Bison do a test on those with different brands?
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Offline Shimy87

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Re: MAP sensor
« Reply #14 on: July 15 2018, 02:26:12 PM »
The gm one is $100....dont want to get a cheap one and have another issue. Will be testing it tomorrow
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87 GN, K&N cold air, gutted cat, TT 5.7 chip, AFPR, 340 Walbro w/ hotwire, 60 LBS injectors, 981 valve springs, 206/206 Cam, RJC Powerplate, LS1 MAF & translator, Vacuum brakes, Hellwig rear sway bar, Energy suspension poly bushings, Razors Alky, Pypes exhaust, 5931 turbo, CK9.5 converter
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