why is Datamaster wrong??

C

Captain Morgan

Moderated User
last time I posted some runs, there was some concern about my Voltage at WOT.

Well I noticed today that even at idle, my Voltage readout on Datamaster is only 13.6.

I knew for a fact that it had to be wrong, so I took out the multimeter and sure enough, Im putting out a healty 14.5V vs. the crappy 13.6V that DM shows.

So any thoughts on this one? Im gonna go check my main ground in a but, but I do have multiple Engine to Frame and Frame to Body grounds.....
 
R

Rufus

New member
All depends where you are measuring the voltage, and how good your multimeter is! The PCM reads the voltage at the ignition wire where it enters the PCM connector; there could easily be a big difference in this and the voltage measured at the alternator. This also could indicate a bad connection in the power feed to the ignition system. In my experience, the PCM readout is +/- one digit (0.1 volts) of the actual value.

The final possibility is that the PCM is bad, and not making the voltage measurement correctly. Th8is is due to internal voltage reference drifting over time - and is a fairly rare occurance. You can check this by measuring the voltage referance supplied to any of the sensors - directly accrodss the sensor. The reference voltage should be very close to 5.000 volts. Of course, you will need a 4 digit multimeter to make this measurement accurately!

HTH,

Gary
 
ed hess

ed hess

race or get outta the way
morgan

if you want to increase what the ecm gets.

run a fat lead from the alternator to the ecmb fuse. i got about .5 more voltage at the ecm and it showed in dm doing this.

ed
 
C

Captain Morgan

Moderated User
Rufus said:
All depends where you are measuring the voltage, and how good your multimeter is! The PCM reads the voltage at the ignition wire where it enters the PCM connector; there could easily be a big difference in this and the voltage measured at the alternator. This also could indicate a bad connection in the power feed to the ignition system. In my experience, the PCM readout is +/- one digit (0.1 volts) of the actual value.

The final possibility is that the PCM is bad, and not making the voltage measurement correctly. Th8is is due to internal voltage reference drifting over time - and is a fairly rare occurance. You can check this by measuring the voltage referance supplied to any of the sensors - directly accrodss the sensor. The reference voltage should be very close to 5.000 volts. Of course, you will need a 4 digit multimeter to make this measurement accurately!

HTH,

Gary
Click to expand...

dude, my multimeter is perfect, spare me the fuckin bullshit and I measured the voltage from the ONLY place you can get accurate voltage readings, is that good enough for ya??

god I hate asking questions on this board, everyone automatically assumes the worst :roll:
 
ed hess

ed hess

race or get outta the way
hey morgan

i dont! :D

but i figured since you were asking you wanted more volts. so do what like i said and im sure you will get a few more.

ed

btw
you really outta settle down. I used to kick the friggin trash cans accross the shop! One day i threw everybody out. locked the doors and went at it with a punk that was being a punk. short of the story is life is just easier if you take it easy..... cya buddy :D

then again somedays even those smiley faces can piss ya off. :fist:
 
4C FED

4C FED

Absolutum Dominium
NJTy180 said:
dude, my multimeter is perfect, spare me the fuckin bullshit and I measured the voltage from the ONLY place you can get accurate voltage readings, is that good enough for ya??

god I hate asking questions on this board, everyone automatically assumes the worst :roll:
Click to expand...

I guess only people with correct answers should reply. :roll:
 
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