Date:         Wed, 25 Oct 2000 23:06:07 -0400
Reply-To:     Dennis Haynes <Dhaynes57@EMAIL.MSN.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <Dhaynes57@EMAIL.MSN.COM>
Subject:      Re: Temp II Again
Comments: To: Jay L Snyder <Jay.L.Snyder@USA.DUPONT.COM>
In-Reply-To:  <85256983.0054B62E.00@CDCLN08.LVS.DUPONT.COM>
Content-Type: text/plain; charset="iso-8859-1"

The ECU does not actually change fuel mixture in any relationship to temp
except for cold start. The ECU basically uses the temp sensor to replace
multiple temperature switches. During cold start, a range is set for cold
start enrichment and operation. When the coolant reaches about 100'F, the
ECU goes into "Closed Loop" operation. At this point, the final fuel mixture
is determined by the oxygen sensor. This is where modifications can be made
to alter the mixture. Even modifying the airflow meter will have little
effect unless things are so far out of range, the O2 sensor can't
compensate.

Dennis


-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Jay L Snyder
Sent: Wednesday, October 25, 2000 11:51 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Temp II Again


As the Temp II sensor heats up, the resistance drops off.  I would assume
this leans the mixture to some "ideal" point.  Has anyone tried
out-smarting the ECU by disconnecting the sensor and manually adding a
resistor across the Temp II wiring (say ~500 ohms) to see if any
improvement is gained.  My '85 Digijet always seems to run rich at both
start-up and hot.  I thought of trying several different resisters, 500,
750, 1000 ohms to see  how it would run during cold starts and hot.  I
checked my sensor (even plotted it on a graph) and it is right on with the
Bentley.  Would running two wires to the front to a digital multimeter give
me reliable numbers as to what the Temp II is doing while driving?  (Poor
man's digitool)  What type of resistor would you use for the above test?
Radio shack #.....

                                                        Jay