Battery Voltage Increases with RPM even after changing Alternator
 

I bought an MS3 Enhanced one year ago from Reverant and am still trying to get the car running properly.

The current issue I'm trying to solve is that the battery voltage is fine at idle but increases if I rev the engine (e.g., 16V at 4k, 17V at 5k, using a quality voltmeter). I'm a noob, I only just found out that the voltage regulation is a joint alternator/ECU thing with the NB. My mechanic replaced the alternator but says the voltage ramping remains the same and is asking me what to do next since he thinks maybe there is a settings issue in the MS3.

Any suggestions? Anything that could be wrong with the MS3? I'm wondering if my issues are relating to ground issues that existed before installing the MS3 but I don't know. I've replaced 2 coils now and I assume they died because of the high voltage. One of those coils died shortly before I installed the MS3 and one of them after. I've tried checking all the grounds I could in the wiring diagram and didn't find any issues. TIA.

Posting an .MSQ file and a log of the problem happening is always a good start when a MS issue is suspected.

I'll qualify this by saying that it's been years since I've fondled an MS3 in any serious way, and others will likely be of more help than I in actually processing said data.



Anything is possible, given what you've told us thus far.


It seems unlikely that a grounding problem would vary precisely and proportionately to RPM.

Easy check: Run TunerStudio, and put a voltmeter gauge on the dashboard. This will show you what the MS *thinks* the system voltage is. Compare this to the actual voltage as measured with your voltmeter. If the two increase / decrease proportionately, then there is not a grounding issue, and probably not a hardware issue in the MS itself. The two figures likely won't match exactly (but they should be within half a volt or so of one another), we're more interested in whether the MS sees the voltage increase and decrease with RPM at about the same rate that the meter does.

And yeah, I'd be a little worried. 14.5v is a good setpoint. 16-17v is going to progressively chew away at your battery.

Thanks Joe, will see if I can do that later today.

NA or NB alternator?

stock NB alternator

OK, so it doesn't move proportionately with RPM, just increases when i bump up the revs. The MS3 voltmeter gauge matched the actual voltmeter. There's quite a bit of flutter on the voltage gauge while the engine is off - is that normal?

This log is a cold start, idle for 1 min, then slowly revving to 5k RPM.

It looks to me like the MS is not controlling the alternator at all. It's just putting out whatever it can all the time. Post your MSQ, or/and consult the person who sold you the MS.

Edit: And don't drive like that- this may fry something!

Que?


https://cimg1.ibsrv.net/gimg/www.mia...d4635a41a3.png


Definitely need to see that .msq.

Thanks guys - this was with the stock PID settings from Reverant. Reverant replied to me saying the MS3 doesn't like PID alternator control and recommended I go to simple control mode and increase the target voltage until the voltmeter goes to 14V. With the target at 14V it was only at 12.5-13.5V so the MS3 was definitely doing something.. will report back after fooling around with Simple alternator control mode.

Unless Reverant MS3 is different from "normal" MS3, I think you should be using "High-speed feedback field control". Works beautiful for me. I'm not even sure what "Simple alternator control mode" is. Is it "On/Off" control?

Yeah I guess Reverant has a different control than you, my available modes are Off, Simple, PID.

So I think the MS3 was delivered with alternator control in Simple mode, and I must have changed it at some point.

I've confirmed that simple mode just doesn't work. The battery voltage just stays at 12.x V like the alternator isn't doing anything, even with me changing the target voltage up to 22V!. This is while the alternator load gauge goes to 100% so I think the MS3 is trying to get it to work but nothing happens.

On the other hand, when I change to PID and increase the gain then the alternator does work, with the calculated output load around 5%. This is with P factor at 70% and D at 50% (originally it was 1%, 0, 0 for the MSL I posted earlier so it didn't have the gain to do any control).

So, I'm not sure what is MS3 issue vs. other electrical. But if MS3 was working properly then it should be able to do something in both PID and simple modes, don't you think?

At least my alternator control seems to be fine now, but Reverant said it should be in simple mode so there's something off.

That and I'm still pulling various codes still with my MS3 Enhanced:
P0219 overspeed
P0106 MAP out of range
P0122 TPS out of range

Argh

Sorry guys, the alternator control does work in simple mode, just had to power cycle and bump the voltage target slightly. So I don't have any alternator issues after all! Thanks for your help.