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Megasquirt: sensor files



I'm sure you saw this, but just in case you didnt..

From: http://www.bgsoflex.com/v22/assem.html

Item #53. 
Install and solder R4 and R7 (2.49K, red-yellow-white-brown-brown). 

Note: these are the two resistors that can be changed for use with 
different coolant (R7) and air temperature (R4) sensors. The 2.49K values 
are for the standard GM sensors (#12146312). If you want to use other 
resistors, you can either change the transfer-function files in the ECU 
processor (requires reprogramming the flash on the processor), or 
switching these resistors and using the current transfer function in the 
ECU, which is easier in many cases. Also, you can mix and match sensor 
types between air and coolant (e.g., use a Ford for air and a GM for 
coolant). Here is a chart of different sensor and corresponding resistor 
type: 

Sensor Type Resistor  
GM  2.49K (supplied)  
Ford  22K  
Bosch  2.2K to 7K, depending on type 

In general to avoid changing the tables in the controller code, the bias 
resistor should have a value equivalent to the that of the thermistor 
sensor when it is at 81 Fahrenheit. 




On Sat, 31 Jan 2004, Dan Bubb wrote:

> I wasn't clear.
> It's not that the VW sensors are not accurate enough. The problem is accurately determining the
> resistance at various temperatures to input the data into Megasquirt.
> I did boiling water, freezing water and room temp with the sensor sitting over a heat register
> blowing ambient air. i.e. heater and AC not on.
> Despite trying to be as accurate as possible the resistance varied quite a bit during these
> measurements. With the sensors installed and MS running the engine temp normally maxed out at 180
> degs which I think is probably low. So, that is the basis of my statement.
> Maybe somebody else can do a better job of measuring the resistance than I did.
> All of this really only applies to the coolant sensor anyway since the 16V has no air temp sensor.
> And if you think about it the accuracy of the coolant temp sensor isn't very important. It isn't
> used for mixture control unless you're cold running and then you can put in any % in the warm up
> bins that your engine needs.
> So, now having thought about it using the stock sensor is adequate for coolant.
> OTOH, a sensor needs to be added for air temp so you might as well use the GM since MS is already
> calibrated for it and it is a low thermal mass sensor. (which could be important for a turbo engine
> and much less so for an NA engine)
> 
> So, Ben! What happened to your MK II 16V?
> 
> Dan
> 
> ----- Original Message -----
> From: "Benjamin Harder" <vwtype53@yahoo.com>
> To: <scirocco-l@scirocco.org>
> Sent: Saturday, January 31, 2004 11:27 AM
> Subject: Re: Megasquirt: sensor files
> 
> 
> >
> > --- Brian McGarvey <brianm@earendel.org> wrote:
> > > Has anybody done the VW sensors? Or do I have to do them or get the GM
> > > ones from the junkyard.
> > >
> >
> >  Yeah, so if Dan says the VW sensors aren't accurate enough, then
> > would the best option be to get GM sensors?  Obviously the GM sensors
> > require no mods to use with the MS... so the real challenge is how
> > to actually USE the GM sensors?  How do you fit a GM coolant temp
> > sensor into the head of a VW 16v?  Make a custom adapter?
> > I'll be doing this soon enough too... so what might the *BEST*
> > solution be here?
> >
> >
> > =====
> > Benjamin Harder
> > 1980 Scirocco 2.0 16v
> > 1993 Passat GLX
> >
> > http://www.geocities.com/vwtype53/
> >
> > __________________________________
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> > _______________________________________________
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> 
> 
> 
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> Scirocco-l@scirocco.org
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-- 
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Brian 
88 16v $2004 GRM challenge car http://www.grmotorsports.com
84 0v Next years car? mid engine... maybe we'll see
82 0v Black 16v kit --parts
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90 90q20v doing daily driver duty. 
91 VFR750F everybody needs a 11-12 sec vehicle.

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