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madkaw

Ms3x install

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The bar sits on the raised bosses on the side of the block. The bosses are clean metal now and I did use dielectric grease between the block and the copper . I even chased the threads on the bolts for the block so that it was a clean connection.

 

All the reading I've done on this MS stuff has made me over cautious about grounds.

Thanks for the answers, now I can finish up these coils !! I drilled extra holes on the copper bar for additional grounds, looks like I'll need them

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You will also notice that the "sensor ground" wire on the DIYautotune harnesses grounds to the same point as the other grounds for MS3.  They all go to the ground pins on the DB37 which all connect to the ground plane of the PCB.  There is no effective difference in bringing the sensors to this sensor ground wire or just tying all the ground wires from MS3 to a common point and tying all grounds from the engine to the same common point.   

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Okay, so you are saying that though there is a dedicated ground wire on the ms3 plug for the sensors---internally on the PCB board they are all grounded in the same place?

So I re read the manual. As you said they state that all grounds basically go to the same place. So is MS wanting you to connect all the sensors together with one ground wire versus each sensor ground running to a ground seperately ?

I don't know why this should be confusing , but I want to get this right.

I believe that I forgot to seperate that ground sensor wire from the rest anyway and grounded it to the engine.

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You are fine.  I just wanted to mention that the DIYautotune harnesses have a dedicated wire brought out for sensor ground, but they all connect to the same place internally.  The other replies were eluding to the sensor ground being different, but in fact it is not different.  All grounds on the megasquirt go to the same place ultimately. 

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A properly grounded system will have a negligible voltage drop between megasquirt and the engine block.  But given the amount of poorly thought out installs I can see why they recommend using the extra "sensor ground" wire for the sensors.  Grounding to the battery as shown in their "no no" picture could have a voltage drop.  I will concede that.  But I say grounding at the buss bar with this install will be no different than using that extra sensor ground.

 

EDIT: if it is different, then more wires should be connected between the DB37 and the buss bar.

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Thanks for your input guys. It seems that with a lot discussions on the forums( not just MS, any performance upgrade) is subject to the subjective. One guy says it didn't work that way or won't work that way because it didn't work for him. Then you see pics of a freaking birds nest they call wiring. I am just trying to nail down what MS wants looking at the manual.

As far as grounding in this discussion , I think MS could have done a better job with the manual. You have to jump around a bit to find answers.

Thanks again I hope this helps for future installs

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Here's why there is some confusion for me with the ground issue. I have attached the schematics that were supplied with my ms3x. They differ from the schematics available on line-especially sensor ground. Sometimes when I am posting I am not at home and I am referencing the on line stuff with my questions. I think the supplied schematic is better and easier to understand.

I am glad to know that I also had the sensor ground pulled and seperated already, so I don't need to repull wires!!!   

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As far as I can tell, the grounding methods as drawn in both the DIY and MSExtra website documentation are electrically the same. All sensors grounds are run to pin 7 on the DB37 connector and the DB37 connector grounds all run to the same place and grounded to the same place the battery is grounded, i.e. the engine block.

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Am I missing it or is there a color code key for the ms3x harness. It's a bitch reading the spark wires.

 

Sam-it seems the supplied schematic is easier to understand when reading instructions-especially when MS specifies grounding through the MS. I understand your point though.

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Internally, all of the ground pins are connected. Theain reason to connect sensor grounds to the ECU is so the sensors reference, or ground, are connected directly to the same point inside the ECU. If a sensor is connected outside on the block or a ground bus, there might be a mismatch in ground level through resistance in wiring or noise from other signals.

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Having a growing respect for you guys have done this job and make it look good too! Things are getting really wirey in the engine compartment.

Pretty much wrapped up the power side of things, now starting the sensor side. getting closer to plugging things in and see if they blow :0

Decided to use this temp sensor fitting off of a 83zx engine I had. Pretty piece that cleaned up well! I have a new GM sensor, but the threads won't match, so I guess I will calibrate the stock sensor.

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Need help!!

Trying to figure out my wiring for my Hall sensor. The MS3x has the sheilded VR/Hall sensor wire with a black and white in the sheilding. So what wire should be signal and which one is ground? I guess I could Assume white is signal, but don't want to assume anything.

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Metro,

thanks for the reply. The output wire from the Hall sensor is black--never like twisting a black and white together, but I guess i need too:)

 

Well I was able to at least test the iginition ON with my MS, and I guess I have that wired right since my Wideband came on and so did my fuel pump :trippen:

small victory-I know, but still. The pump shut off after just a few seconds since the MS sensed no rpms.

Now waiting on my cable.

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