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I see your concern, but I do believe that the ecu supplies +5v sensor power. This should be the case with both stock ecu and ms. If the stock baro sensor receives +5v from the ecu, then it is getting it from the ms, and thus will be correct for my external MAP measurements.
My MSLabs MS3 does not connect any of the wires to the stock EGR/MAP/baro sensors.
Have you checked for +5 with a voltmeter, or just a wiring diagram?
My MSLabs MS3 does not connect any of the wires to the stock EGR/MAP/baro sensors.
Have you checked for +5 with a voltmeter, or just a wiring diagram?
--Ian
Hold up. Where do you think the TPS gets +5v from? The ecu.
How are multiple sensors normally fed power? Splices in the harness.
The factory baro sensor likely gets +5v from the same lead that the ecu supplies power to the TPS from. I have measured +5v at the oem baro sensor plug with a meter, that's what I did when I said I had confirmed there was +5v at the oem baro sensor.
The factory baro sensor likely gets +5v from the same lead that the ecu supplies power to the TPS from. I have measured +5v at the oem baro sensor plug with a meter, that's what I did when I said I had confirmed there was +5v at the oem baro sensor.
It wasn't clear to me what "confirmed" meant, which is why I asked.
I'm reasonably sure there's no generic "+5v output" line coming out of my MS3. I built a wiring extension harness for it, and to do that I opened up the case, identified every pin that was actually connected, looked up where it went in the factory wiring diagram, and put it all in a spreadsheet. I only have access to the spreadsheet right now (diagram is at home), but nothing in there looks like it could be a generic +5 output unless it's one of the "instrument cluster" wires (there's more than one and I didn't bother to trace out which did what). I'll go look it up when I get home.
It's also possible that the factory ECU doesn't need that much precision on the few +5 sensors it has. I would expect that if the TPS is off by 5% then it doesn't matter, and the stock MAP sensor is only used for EGR control which is closed loop so can probably tolerate errors. That's not true of the 3 bar GM MAP sensor you're using for primary fuel control.
ECU pin 2I on your 99. That 5v reference is definitely used for the TPS. 5 volts goes into it then voltage drops depending on throttle position due to a change in resistance with a voltage dividing network if I'm not mistaken.
ECU pin 2I on your 99. That 5v reference is definitely used for the TPS. 5 volts goes into it then voltage drops depending on throttle position due to a change in resistance with a voltage dividing network if I'm not mistaken.
OK, I had that marked as 12v in my spreadsheet -- not sure why.
Are you mounting the GM sensor in the engine bay or under the dash next to the ECU?
Looks good. I would keep the wastegate as-is, the extra boost up top is flattening out the torque curve! That's what you want, or, at least what I want. Flat, broad torque curve.
I went from 0.63 to .82 A/R turbine, yeah, I'm going to swap back to the 0.63 A/R. I think I gained 5-10 HP, and lost a ton of spoolage which ultimately made it slower. Cool to see how much it helped your setup!
08-30-2017, 06:31 PM
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