RE: 7749 guru needed....

[Barry Tisdale <btisdale@cybersol.com>]

Ok, just did some research in the 7749 SyTy F29 Closed Throttle table,
trying to dope out the x-axis calibration.  My idle normally runs around
14-15"Hg vac, equivalent to ~50kPa, using a 3 bar MAP sensor.

First, I set F29 & F30 back to stock values.

THEN - started reducing only the 50kPa value at 600 & 800 RPMs.

Boom - there it is, works as expected.  Cause & effect 100%.

SO - the x-axis IS in kPas *not* in %age of MAP sensor output.  "50" would
correspond to somewhere in the low boost range, not an idle value, if those
figures depended on the MAP sensor output.  Question remains, where *does*
the BARO value come from?  Separate sensor in the ECU?  Doesn't seem to
come from the MAP sensor, as the 3 bar value would be all wrong.

Another thing here, is the 3 bar MAP sensor puts out, say, 2.5v @ 150kPa,
where the 2 bar sensor puts this out @ 100kPa.  YET, changing the values @
50kPa, using a 3 bar sensor, profoundly affects the idle A/F, where even
taking the values @ 30kPa to zero had no effect on the idle.  It would seem
that you'd have to multiply all the x-axis values by 1.5 when using a 3 bar
sensor (30kPa would = 45kPa) in place of a 2.  Again, not, and how come??

Reason the formerly zero-ed out values in the extreme upper left of the
table had no effect was that they were *never* being accessed; just my
reducing values in the F30 table produced the right idle A/F ratio.  Not
the best way to go about things.

Ok, now to re-do the idle, just using F29 CT table. One step ahead, one back.

Let's pool our info on this stuff, & I'll put together a "how to" paper
when all's said & done.
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