haltech mapsensor change-offer to pay for switch

[John Dammeyer]

The MPX2200AP, according to my Motorola Selection Guide,  is an absolute
pressure transducer listed as good for 0 to 29PSI or 0 200 kPa.   It's
temperature compensated and calibrated on chip.

Since atmospheric is ~15PSI this sensor is good to 14 PSI boost.

In other words... you don't need to change it unless the Haltech processor
input cannot handle the range and somehow I doubt that.

John Dammeyer


----- Original Message -----
From: "Jörgen Karlsson" <jurg at pp.sbbs.se>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, January 30, 2001 5:54 PM
Subject: RE: haltech mapsensor change-offer to pay for switch


Hi

I can't do the switch for logistical reasons.

But anyone with some electronic knowledge should be able to make
modifications for an external pressure sensor. The sensor in the ecu is
likely to be included in a three way voltage divider, the sensor in the
middle. The differential pressure over the sensor is then amplified and
converted to a ground referenced signal. With some knowledge of measurement
technique and a data sheet over either the lm324 or for the sensor itself
the signal conditioning circuit should be easy to identify. Where it
connects to the adc the trace must be cut, then only connect the external
map sensor with suitable protection and maybe a voltage divider and it is
finished.

By the way, I worked at Volvo, building cars when your car was built! Small
world?

Jörgen Karlsson
Gothenburg, Sweden


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