Re: [Amc-list] TBI EFI tuning...

[Glen Hoag <hoag@xxxxxx>]

It depends on the MAP sensor, but most seem to have nearly linear 
outputs from 0-5v.  0 is 0kPa; 5v is the limit of the sensor.  1 bar 
sensors are probably 115kPa max, 3 bar sensors are 300kPa max.  This 
is how the Freescale (ex-Motorola) sensors work.  I think that's what 
GM buries inside their sensor modules.  If you can measure the sensor 
output and have an accurate barometer, you can determine the sensor 
calibration fairly easily by opening the sensor port to ambient 
pressure.  A 1 bar sensor should read around 4v, while a 3 bar sensor 
will be about 1.67v.  You can find data sheets for common sensors on 
Freescale's website.  Look for MPX4115AP and MPXH6300.

The transfer function for the MPX4115 family is 
Vout=Vs*(0.009*P-0.095), where Vout is the sensor output, Vs is the 
supply voltage (nominally 5v) and P is the pressure in kPa.

--Glen


At 04:18 PM 11/10/2008, Tom Jennings <tomj@xxxxxxx> wrote:
>OK, I am now doing the thing I sort of dreaded doing... driving down the
>road with a laptop on the passenger seat. With a simple mis-click I
>poked the injector base-pulse number such that it immediately stalled!
>COol! Um yeah. At least I wasn't driving then.
>
>But I did tweak the thing for a far more correct setting for the 232 in
>the Classic. No more adjustable MAP sensor!
>
>You could spend forever tweaking this crap, I can see now. But after I
>solve a few mysteries (eg. TunerPro RT shows manifold pressure as a
>voltage reading from the MAP sensor; the fuel tables use manifold
>pressure, in Kpa (Kilo-Pascals), how to convert?)

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