Tuning in Open Loop for Newby

[David Cooley]

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 at triad.rr.com
Packet: N5XMT at KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
I am Pentium of Borg... Division is Futile!
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