Transducer/Power Logger issues!

[scrobbyd]

Would anyone happen to have a clue as to why a transducer would suddenly start reading 3 volts instead of 5 volts on Power logger? I question Bob Baily of this issue and he told me that my transducer had gone bad. So yesterday I put another brand new transducer on my car and still having the same issue. Fuel pressure is showing in the 70 lbs range at idle with a little under 3 volts. My fuel pressure has been verified with an accurate gauge to be 37 lbs at idle. I've checked ground 12 volt source and signal wires. All are good. So where do I go from here?

 

[jpwalt1987]

Robby, I will buy that other sensor from you. Let's get together this coming week and try one on my car and laptop. Just a thought.

 

[TurboBob]

measure the ground, +12v, and signal voltages with a DVM (digital voltmeter). if the sensor is putting out 3v, then its the sensor. If it reads something else, then there is a connection issue from the sensor to the PL.

Bob

 

[jpwalt1987]

Bob , what is the scale for these transducers psi vs voltage?

 

[BobbyBuick]

and is the voltage in the INI file correct for the transducer

 

[BobbyBuick]

go to the INI file and read until you see the input number either 4 or 5 look at the voltage scale and you can change it to match the output and custom name the input to read FPR

 

[TurboBob]

Bob , what is the scale for these transducers psi vs voltage?

I believe Caspers sensor is 1v = 0 psi 5v = 100 psi

 

[scrobbyd]

Bob I've put my DVM on the pigtail that connects to the transducer on the 12v side and ground, it reads 11.63v. Next I tried from the analog 4 to a ground 2.4v ignition on car off.

 

[salvageV6]

Take the transducer output wire off the powerlogger pin, leaving the +12 and ground connection on it and also read the voltage see if it matches the 2.4 volts disconnected from the powerlogger.

 

[TurboBob]

that should be 35psi on a caspers sensor (100 PSI B setting in PL)

 

[scrobbyd]

I tried both new and older transducers. Testing just signal wire off of analog bus bar to good ground and got 2.47v.

 

[scrobbyd]

Okay so this is what I've tried now. I cut the signal wire where it was originally spliced to pigtail. With the car running I put DVM (red) on signal wire and (black) on good ground and pigtail plugged into transducer. Car running at idle was 2.40v. I then pulled vacuum line off regulator and voltage went to 2.68v. Replace vacuum line 2.40v, then removed once more and got 2.68v.

 

[tonka]

Okay so this is what I've tried now. I cut the signal wire where it was originally spliced to pigtail. With the car running I put DVM (red) on signal wire and (black) on good ground and pigtail plugged into transducer. Car running at idle was 2.40v. I then pulled vacuum line off regulator and voltage went to 2.68v. Replace vacuum line 2.40v, then removed once more and got 2.68v.

As Bob said, 2.4 VDC from the sensor equates to 35 psi on a 1-5V/0-100 psi sensor. Look into the PLC.ini file as BobbyBuick recommended for how the input (you have this sensor hooked up to) is set up

 

[BEATAV8]

12V source? Is the sensor supply supposed to be 5V source? Mine is a 5V sensor, powered from the TPS 5V.

Some sensors may be 12V supply. Some are 5V supply. Depends what you got....

 

[TurboBob]

caspers sensors are 12v according to the web site.

AEM sensors are 5v

 

[TurboBob]

Okay so this is what I've tried now. I cut the signal wire where it was originally spliced to pigtail. With the car running I put DVM (red) on signal wire and (black) on good ground and pigtail plugged into transducer. Car running at idle was 2.40v. I then pulled vacuum line off regulator and voltage went to 2.68v. Replace vacuum line 2.40v, then removed once more and got 2.68v.

that looks like the sensor is working, is the voltage not being shown properly in the PL?

 

[scrobbyd]

I think that i found the issue! The drop down box next to Analog 4, had "Pressure 4" selected instead of "Pressure 100psi". Problem now seems to be fixed. Seems as though before my only option was "Pressure 4" in the drop down section. Obviously I need the tweaking!!! But at least now I know that I have 3 working transducers...

Thanks for all the input and help