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Old 10-30-2014, 08:43 PM   #1
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Default Tuner Studio reading wrong voltage

I'm running MS1 on a 95 turbo car. In tuner studio it shows 13.6-almost 14 volts. At the battery it reads a normal 12.5-12.7 while running. Also tuner studio shows no draw when headlights, heat, radio or any combination of voltage drawing accessories turned on. Can I compensate with easy therm or is there another way to correct this. Thanks for any advice
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Old 10-30-2014, 08:53 PM   #2
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Quote:
Originally Posted by LooneyJam View Post
I'm running MS1 on a 95 turbo car. In tuner studio it shows 13.6-almost 14 volts. At the battery it reads a normal 12.5-12.7 while running. Also tuner studio shows no draw when headlights, heat, radio or any combination of voltage drawing accessories turned on. Can I compensate with easy therm or is there another way to correct this. Thanks for any advice
Uhhh you should be ~14V while running...
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Old 10-30-2014, 11:25 PM   #3
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Ya but why would it read different at the battery? Running or not. It seems to run good but I think it's over compensating the injectors
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Old 10-30-2014, 11:31 PM   #4
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What are you reading it at the battery with? If DMM, when is the last time you changed the battery in it?
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Old 10-30-2014, 11:32 PM   #5
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Reading with a fluke/volt meter. Battery is 2 years old.
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Old 10-30-2014, 11:33 PM   #6
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Sorry but, DMM?
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Old 10-31-2014, 08:37 AM   #7
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Digital Multi Meter. Change the batteries and check again. Or check with a different meter altogether
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Old 10-31-2014, 08:46 AM   #8
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MS needs to match voltage as read at the injectors.

if you're only reading 12v while running your alternator isn't working.
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Old 10-31-2014, 09:06 AM   #9
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Originally Posted by Braineack View Post
if you're only reading 12v while running your alternator isn't working.
^ This.


The battery should read around 12v when the engine is not running.

A basic principle of electronics is that in order for current to flow from the alternator into the battery, the voltage produced by the alternator much be higher than the battery voltage.

A comparable scenario here would be if you had two balloons connected to one another via a straw. In order to force air from one balloon into the other, you squeeze the balloon, causing the pressure (voltage) inside it to rise. Air then flows from one to the other until the pressure equalizes between the two.

Same deal here. In order for the battery to actually charge, the alternator is run at a higher voltage than the battery's normal resting voltage; the exact voltage differs somewhat from car to car, but 13.8v is often cited as the ideal, with observed readings ranging from around 13.5 to 14.5v.

If you read less than this at any point in the system while the engine is running, you have a problem. Maybe a bad alternator, maybe a wiring problem in the car, maybe your meter is just out of calibration or malfunctioning. These things happen.
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Old 10-31-2014, 01:20 PM   #10
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So I may not have a problem..... I'm gonna try and check the voltage at the injectors to see if it matches. My tuner was saying the extra voltage will over compensate the injectors. Is this true? What you guys said makes sense. Thanks for the help!
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Old 10-31-2014, 01:50 PM   #11
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voltage has an effect on the dwell time of injectors, so MS adjusts the PW of the injectors based on the system voltage in order to compensate correctly.

that's why it's important that the MS is tuned to match the voltage at the injectors.

you might see 14v at the battery but only 13v at the injectors.
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