99' MSPNP2 Blown Up Battery / Voltage Regulation Issues
#1
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I've already blown up my recently purchased MSPNP2 for my 99' and the main board replaced. When i got it back, I ran the car for a day on the MSPNP2 with the battery boiling over causing a rotten egg smell because it was being overcharged by the alternator. From what I understand, the stock ecu handles vreg of the car. I bought a new battery after the old one blew up from overheating (the fuel pump burst fuel lines from running off 14+ Volts) and installed the stock ECU for now and it runs perfect. I just want my megasquirt to work for more than one day you feel????? There is no setting for vreg in Tuner Studio and the board has no jumpers or dials to adjust anything related to voltage regulation. What is the fix for this problem? do i have to make my alternator internally regulated??? What am I not clearly seeing in this bullshit. Why do NA miata owners have it so easy wiring up their MS. I cant even figure out how to wire up the AEM wideband to the MSPNP. I cant even wire it through the options port for ***** sake. Can someone please for the love of god help me?????
#2
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The MSPNP2 should regulate voltage by itself, 14.5V is normal. Your fuel lines wont burst with high voltage, there has to be some other electrical problem.
As for the AEM wideband, it should have 4 wires:
1. 12V - tap cig lighter
2. Ground - anywhere on chassis or also from cig lighter
3. 5V Wideband - wire to options port or wire where the stock front o2 sensor connector is. The stock connector also has 4 wires, you want to use the signal wire (solid black or solid blue).
4. Narrowband - dont use with MS
As for the AEM wideband, it should have 4 wires:
1. 12V - tap cig lighter
2. Ground - anywhere on chassis or also from cig lighter
3. 5V Wideband - wire to options port or wire where the stock front o2 sensor connector is. The stock connector also has 4 wires, you want to use the signal wire (solid black or solid blue).
4. Narrowband - dont use with MS
#3
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The MSPNP2 should regulate voltage by itself, 14.5V is normal. Your fuel lines wont burst with high voltage, there has to be some other electrical problem.
As for the AEM wideband, it should have 4 wires:
1. 12V - tap cig lighter
2. Ground - anywhere on chassis or also from cig lighter
3. 5V Wideband - wire to options port or wire where the stock front o2 sensor connector is. The stock connector also has 4 wires, you want to use the signal wire (solid black or solid blue).
4. Narrowband - dont use with MS
As for the AEM wideband, it should have 4 wires:
1. 12V - tap cig lighter
2. Ground - anywhere on chassis or also from cig lighter
3. 5V Wideband - wire to options port or wire where the stock front o2 sensor connector is. The stock connector also has 4 wires, you want to use the signal wire (solid black or solid blue).
4. Narrowband - dont use with MS
![](https://cimg4.ibsrv.net/gimg/www.miataturbo.net-vbulletin/684x1273/snapchat_2003343220_a28929e68a3c384ff041142280510a4c98f84e5d.jpg)
line from walbro 255 burst after voltage spike
#7
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You're barking wayyyyyy up the wrong tree with that fuel line. With the assumption that the line is actual EFI hose, there is no way possible the line burst due to pressure caused by pump.
Also: Your Megasquirt is not controlling the alternator correctly because it doesn't have native alternator control.
You bought a brand new Playstation 2 in the year 2020.
Also: Your Megasquirt is not controlling the alternator correctly because it doesn't have native alternator control.
You bought a brand new Playstation 2 in the year 2020.
#16
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Was there any resolution to the high DC voltage issue in this thread? I'm hunting for a solution to a voltage regulation issue.
I am getting Battery voltage readings of 17-19 vdc since the MSPNP2 installation (in my 2000 NB with FM Turbo) which I believe is causing these problems and I suspect also could affect my tuning. The problem has blown multiple headlight filaments and shuts down the radio due to excessive voltage.
I have completed the following troubleshooting steps:
- Confirmed fully charged battery
- Confirmed voltage at battery (with a high quality multimeter) is matching Tuner Studio indicated battery voltage
- Removed and bench tested alternator at a parts store, confirming 15.1 vdc output
- Double checked block, chassis grounding with the MS and alternator connections
Is there a pot or something on the circuit board which I can use to adjust the voltage down? My MS dealer thought the MS had an adjustment point but i can't find any documentation to verify that. The MSPNP2 does not have any of the small blue adjustors like I've seen on other MS boards.
I am getting Battery voltage readings of 17-19 vdc since the MSPNP2 installation (in my 2000 NB with FM Turbo) which I believe is causing these problems and I suspect also could affect my tuning. The problem has blown multiple headlight filaments and shuts down the radio due to excessive voltage.
I have completed the following troubleshooting steps:
- Confirmed fully charged battery
- Confirmed voltage at battery (with a high quality multimeter) is matching Tuner Studio indicated battery voltage
- Removed and bench tested alternator at a parts store, confirming 15.1 vdc output
- Double checked block, chassis grounding with the MS and alternator connections
Is there a pot or something on the circuit board which I can use to adjust the voltage down? My MS dealer thought the MS had an adjustment point but i can't find any documentation to verify that. The MSPNP2 does not have any of the small blue adjustors like I've seen on other MS boards.
#17
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Yes I found the problem a while back, sorry for not posting it. The MSPNP2 for the 99 Miata regulates voltage within the ecu itself. The problem was that when I received my ecu from Diyautotune after completing repairs, the voltage regulator was set to always output the maximum voltage. According to them, it can only be adjusted by one of their engineers. I sent the ecu back and they fixed the problem for free.
#18
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To reinforce this fix, for anyone else dealing with crazy alternator/battery voltage after installing the MSPNP2 MM9900..... My voltage was reading 17=20vdc after the new install, which blew headlight filaments and shut off the radio due to over voltage. The problem was indeed with the MS, which was repaired under warranty by DIYAutoTune. They replaced component U1, which fixed alternator voltage regulation. I now have voltage readings of 13.5-13.7, verified with a quality multimeter at the battery.
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