Battery voltage is off on TS - need help

[Yves]

Was working on her some more and found out that TS reads a lot lower than what I'm seeing with a multimeter on the battery terminals. The multimeter shows 14.2-14.3V and on TS 13.6V. Is this something I should adjust. I read to manuals of TS but there is not a lot of explanation in the calibrate battery voltage section.

Thanks

Edit : I also checked voltage across the battery terminals on the relay board (both switched and batt) and the multimeter showed 14.4V and TS only 13.8-13.9V

[Michael]

I had similar issues with Battery Voltage and thought it was a calibration issue with TS. I was seeing 11.6 to 12.3 in TS and 12.4 - 12.8 at the battery on my DVMs. I improved the grounding and also the point at which I sourced the 12v +ve supply ( I was dealing with a starting issue at the time). The reading in TS then came to within 02 or so of the DVM which I consider acceptable.

Best Wishes - Michel

[Yves]

Hi Michael,

Best wishes as well.

Just thinking out load. I can understand there would be some difference when measuring voltage across the battery poles but even when I measure across the 12VDC and ground on the relay board I'm getting similar readings on my voltmeter but a different indication from TS. I'm using the dedicated wiring between the MS and the relay board, so nothing has changed there.

[Michael]

I guess one thing to look at with your meter is the actual voltage arriving at your MS. What voltage do you see between ground, say pin 19 of the DB37 and Ign power at pin 28? and between ground on the pcb and pin 1 of U5 (The 5v regulator)? TS gets its reading from what appears on the MS board, I have to say that I am not completely familiar with the relay board set-up, but purely from an electronics point of view there may be losses between the relay board and the MS PCB where TS gets its measurement from. If you can establish that the on-board voltage differs significantly (> +/- 0.3V) from that displayed by TS then you can start looking at TS. Now I don't get this on mine, but I have heard that some versions of TS have a facility for Calibrating Batt V. Perhaps someone else can help here??

Michael.

[dragbug]

Mine was off as well and I am also using the relay board. There is a batt calibration in TS that you can use to close the gap. I read some place in these forums that it was best to measure the voltage at the coil or the injectors versus directly from the battery and then calibrate the battery v based on that. That's what I did and I think it is better. Like almost all of the sensors, there is some slight differences between what TS shows and what is actually happening.

[Yves]

I tried to get to some contacts on my v3.57 board to measure but there was no place to put a probe. I measured across the terminals of the injectors to the ground and adjusted the voltage for TS to read correctly.

I have my airboxes of in order to do some rewiring and will do my injector dead time test

[sedd]

I saw voltage differences as well. I can't remember the amounts but they were significant enough for me to want to get them closer. Mostly I wanted a good reading so I could tell what my charging system was doing. The variation didn't make sense to me because I had all but the ms3 power fuse pulled and there was not much current flow, as the engine and thus ms3 system was not in use. I used a power supply to vary the voltages, it also had a meter on it.

I happened to have two inexpensive meters and I was surprised at how much difference they had between them. So I figured it was possible tuner studio was accurate and my meters were off. I adjusted tuner studio and got it and the meters, as well as power supply close, so that my injector testing flow settings closely matched the test voltages.

there is a drop down in the tools tab, calibrate battery voltage, that I changed to get it closer. I changed both upper and lower values. I vaguely recollect the upper value changed from 29.8 to 30.1, so there was not much value change. It was not possible to change the values to get exact same readings, also there seemed to be several values that would give the same tuner studio value, so I used the mid point of those.

I think that once you set this and then tune your system any small voltage errors will not make a difference. I don't think a person should change this once it is set.

[Yves]

When doing my injector test, both the V-meter on the power supply and my multimeter showed the same and the TS reading was of. I reset the battery voltage an now it's reading about .1 to high, which I do not seem to be able to adjust anymore.

[nismoautoxr]

FWIW I went through this early on . In the end ...as long as you are not fighting any other symptoms such as dimming lights , dragging starters, intermittent anomalys.....then pursuing a offset of .5 volts or so is probably like charging windmills. Simply if your DVOM readings are plausible then Id largely disregard TS differences.