Re: Tuning in Open Loop for Newby

[rr <RRauscher@nni.com>]

The open loop AFR correction vs. MAP and AFR correction vs. coolant temp
tables are only used in open-loop (no O2 sensor feedback). These 'corrections'
are used until the engine and O2 warm up enough to go closed loop.

Once in closed-loop, the desired afr is set to 14.7 (this is used in the bpw
calc).

If starting to tune in open-loop (no O2), then set the afr vs. map table to the
14.7 value. You can then look at the O2 sensor and make the gross adjustments
required. Once close, go to closed-loop (O2 feedback), set the blm min/max
to 128, and use the int to tune.

Open-loop tuning is only needed when you are starting with an engine that
is radically different from anything gm has produced. I've used it on
occasion in a couple of areas of the ve table.

BobR.

WEG1192@aol.com 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?
>
> 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.
>
> Thanks

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