1227165 Tuning Advice

[Mark Romans]

In my opinion I wouldn't worry about centering the BLM numbers.  If you have
to you could find the base pulse width fuel map and change the numbers there
to center the block learn, but frankly unless you are getting really weird
110 or 150-160 BLM numbers I wouldn't really worry about it.


>Hi Mark,
>
>I compared the stock chip BIN with the ASM bin. No changes were made in the
>code area. Updates were implemented only in the tables.


I don't know anyone who knows enough about the code to mess with it.  Even
GM only changes the lookup tables.  If the code needs to be changed that
goes to  a different group.
>
>As discussed earlier, at WOT the BLM & INT jump to 128. Since the system is
>somewhat rich at part-throttle conditions does this mean,
>
>1.
>The computer pulls fuel out at WOT (resulting from BLM <= 128 @ part
>throttle). End Result : lean
>
>2.
>The computer does not implement a BLM compensation at WOT. End Result :
lean
>
>Can I look in the lookup tables or code to find out if BLM based WOT
>compensation exits??? If so, please send the information to me.
>
This has been stated several times.
IF THE BLM NUMBERS ARE ABOVE 128 THE ECM USES THE SAME CORRECTION AT WOT
(PE).  IF THE BLM NUMBERS ARE BELOW 128 THE ECM GOES TO 128 FOR PE
CORRECTION.



>One clue supporting the lean theory exists in the BLM data that I posted. I
>managed to record some closed-loop part throttle BLM Cell 14 & 15 data. The
>RPM range was 2200 - 2500 and the LV8 range was 167 - 180. The BLM was 123
>and the INT range was 136 - 143. This indicates that a fair amount of fuel
>was added to the base map.
>
Actually the 123 means fuel was being pulled out long term and short term
was being added back in.  The longer the INT stays high it will pull the BLM
numbers higher.
>For a typical TPI system, what is the maximum obtainable fuel pressure???
>Presently, my fuel pressure is adjusted for a 44 PSI idle and 50+ PSI WOT
>condition.
Same settings I use.
>I have a general MAF fuel mapping question for you. If the BLM is all over
>the place (above & below 128 for various RPM & load conditions), does this
>indicate that the engine VE is different than the data in the Injector PW
vs
>RPM vs Load table ????
Yes, or that the MAF map is off a bit, I really wouldn't worry about it, it
corrects itself, it's designed that way.
Does this table use "Load" or "LV8" ???
As far as I can tell EVERYTHING uses LV8.
I am
>suspicious that this table is slightly off. If I increase the FP to
>compensate the WOT condition, then I would expect the part-throttle BLM
>numbers to drop down even more. Presently, they dip down to 110!
>
>I will play with the FP and base timing initially, but I do not believe the
>engine will be optimized over the entire operational envelope. If I
decrease
>the base timing, the part
>throttle response will most likely suffer. As the FP is increased, the part
>throttle BLM will decrease.
>
>The goal is to center the part throttle BLM and stop the WOT knock count
>generation.

I suspect two different problems/issues.  Spark knock is timing,  I don't
like the idea of using fuel to quell knock.

>
>Thanks for the Advice,
>
>Bruce
>
> From: Mark Romans [SMTP:romans at pacbell.net]
>> Sent: Friday, April 23, 1999 12:59 AM
>> To: gmecm at efi332.eng.ohio-state.edu
>> Subject: Re: 1227165 Tuning Advice
>>
>> Also with a stock chip, the ecm will add an amount of fuel to WOT that it
>> adds to part throttle, if however it is pulling fuel out, it will revert
>> to
>> BL of 128 at WOT.
>> Mark
>> -----Original Message-----
>> From: Bruce Wilcox (EUS) <EUSBEW at am1.ericsson.se>
>> To: 'gmecm at efi332.eng.ohio-state.edu' <gmecm at efi332.eng.ohio-state.edu>
>> Date: Thursday, April 22, 1999 12:14 PM
>> Subject: RE: 1227165 Tuning Advice
>>
>>
>> >Hi John,
>> >
>> >I think the ECM is learning over time. The long term BLM is low (110)
but
>> >the short term integrator is around 128. I believe this indicates that
>> the
>> >ECM has compensated.
>> >
>> >Bruce
>> >
>> >> -----Original Message-----
>> >> From: jgwynne at mrcday.com [SMTP:jgwynne at mrcday.com]
>> >> Sent: Thursday, April 22, 1999 11:35 AM
>> >> To: gmecm at efi332.eng.ohio-state.edu
>> >> Subject: Re: 1227165 Tuning Advice
>> >>
>> >>
>> >>
>> >> | > 1.
>> >> | > The nominal BLM is consistently below 128. Depending on the exact
>> BLM
>> >> | cell,
>> >> | > the nominal value approaches 110. The integrator hovers around 128
>> +/-
>> >> 5.
>> >> | > Since the BLM is low and the integrator is OK, my guess is the
fuel
>> >> | pressure
>> >> | > is high (44 PSI @ idle, 50+ PSI @ WOT). Is this a reasonable
>> >> diagnoses??
>> >> |
>> >> | Have you run any performance base lines?..  Fuel Pressure makes a
ton
>> of
>> >> | difference at WOT..  Find out where your at with WOT AND cruise,
then
>> >> judge
>> >> | where you need to move things.  (Also, measure PW/Duty cycle).
>> >>
>> >> Why does fuel pressure make a ton of difference at WOT? The ecm should
>> >> learn a correction for pressure while in closed loop that is applies
to
>> >> the open loop WOT. Changing fuel pressure would allow injects to flow
>> >> more if needed, but the ecm should, over time, learn the correction
>> >> factor for the pressure being used. yes?
>> >>
>> >> john
>> >
>