Step 54 of MS assembly
 

Im up to the part of the MS install R4 and R7.

The "how to" says to remove R7 if sharing the stock CLT sensor. Braineak mentioned in some thread that it threw off the calculation on his car. But my question is, how does it even work in the car if the ECU doesnt even register the information sent to it by the Megastim when monitored in Megatune if the resistor is not in place.

Wouldnt it be smarter to follow the megamanual and get the appropriate resistor for a mazda? 2.2k ohm?

Now R4 refers to the AFM supposedly according to the "how to". How do we know that R4 is appropriate for our cars? I know we don't use AFM because of MAP, but I am curious.

Is there a separate table somewhere to determine the appropriate bias resistor for that? Why even install the resistor if we dont use it?

The megamanual all in all is very confusing about these two because it refers to them both together in one step and then links them as being responsible for the CLT.

http://www.megamanual.com/v22manual/sharesen.htm

Looks like R4 is for AIT not AFM, which answers my second question. That would mean the one sold by DIYautotune has the appropriate resistance to match the 2.49k ohm bias resistor.

This link also says to leave R7 out if sharing, but I still dont understand how its supposed to work.

R7 splits the signal but if you are sharing already you don't need it resplit. any way you cut it my max temp with r7 installed was 74 C with r7 out it has gone to 104 or so,

when you finally flash the firmware you have to setup your intake and coolant sensor resistance values.

easytherm is already preloaded with the default values for the sensors, so with the additional resistor added inside MS, the bias resistance has changed and MS will display the temp value incorrectly. You can leave it in and then figure out what the bias resitance with R7 installed is.

and yes, R4 is for the AIT.

these two resistors are specifically the intake and coolant temp bias resistors.

So what are the bias resistors supposed to compensate for?

Splits it for what reason? I don't understand. If the AIT that we install is not shared with anything, why does the MS need to split it internally?

the bias resitors move the reference voltage around, iirc.

Esaytherm generates a table with your giving inputs so MS can correctly understand what the resistance value it sees means.

example:
notice the bias resistance statement? it's looking for a specific bias, when you're sharing that signal with the stock ECU the bais resistance is raised, becuase the stock ECU has it's own resistor. So the scale on which you generated your table will be off.

what will happen if you dont remove r7 and share the coolant sensor with the stock ECU is your temps will display 30*F cooler than they really are.

Thats pretty awesome.

So I don't have to make a separate thread. How come Q9 and Q12 have to be on mica insulators?

I know those will get grounded out without the insulators and the MS will not work.