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Re: Tuning in Open Loop for Newby
At 02:39 PM 8/23/2000, you wrote:
After reviewing a bunch of EPROM bins, I have a question about tuning. My
understanding is that the tuning is for closed loop operation. But to tune,
you set the closed loop enable temp way high to keep the ECM from entering
closed loop. So now, are you tuning in open loop or closed loop? If open loop
is nothing more than the closed loop tables without O2 feedback, what are all
the open loop AFR correction vs. MAP and AFR correction vs. coolant temp
tables for? Seems to me that these tables would interfere with proper tuning
for closed loop operation. If you tune with those corrections applied, and
then you drive in closed loop, seems that your tuning would be inaccurate?
Those tables for desired AFR are only going to be used during closed
loop... Otherwise, there is no AFR feedback (O2 feedback) to tell it
what's happening... On a MAP vehicle, the VE tables are what you tune for
fuel while in open loop... On a MAF system, there are tables for fuel also
(can't remember what they are called) that are for openloop operation...
Closed loop uses these tables as a starting point, and applies the
corrections for the CTS and MAP to them... Once you get it where you like
it open loop, set it back to closed loop and adjust the modifier tables to
suit your needs.
Also, it was mentioned a while back that setting ignition timing advance to
just before knock occurs at all RPMs is not always the best setting. If
that's the case, what criteria is used as your tuning goal? Best acceleration
under WOT? Best mileage? Etc.
Depends on what you're tuning your car for... For mileage, you adjust it
for best mileage... For performance, tune it for best
acceleration. Everyones needs are different.
===========================================================
David Cooley N5XMT Internet: N5XMT@triad.rr.com
Packet: N5XMT@KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
I am Pentium of Borg... Division is Futile!
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