Barry Gardner wrote:

Paul,

After sending my last missive, it occurred to me that there were
a couple other things to mention about the monitoring the engine.
I'd focused on the ignition and fuel control of the engine so
much that I forgot to at least make passing reference to the
temperature and pressure sensors that we all use to monitor the
health of the engine--water temp, oil temp, oil pressure. There
is no single value that these sensors must read in order for the
engine to work (i.e., the engine functions fine within a range of
readings) but these sensors are certainly crucial to monitoring
the engine. I was going to say that these aren't part of the EFI
loop but realized that, too, would be incorrect.

I don't know Tracy does it but the enrichment map for starting
EFI systems uses a water temp sensor to enable the engine
computer to figure out when the equivalent of choke or primer is
needed. If Tracy already requires that info already, then maybe
that's one of those variables to put up there on the display
rather than let the computer swallow the data.

One of the more clever hacks of the stock RX7 engine computer
puts a control on the water temperature input to the computer,
thus fooling the computer to enrich the mixture, though the car
is already warm.

Barry Gardner
Wheaton, IL

I think Tracy probably use intake air temp for starting.

That hack has been around almost since the begging of EFI.
I had a VW Sqareback with Bosch analog EFI around the late 1960's.

Paul Lamar
 
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