3.8 tuning questions

[BTLD_LS1]

First vehicle I am working with is a 00 Impala and I am working on the Power Enrichment tables which are NOTHING like what I am used to on my LSx's.

It appears that GM sets the "base" AFR at 13.6 for PE mode.
the add vs. TPS is all zeros, so no change here.
then when looking at the add vs. RPM table, they are only leaning it out to about 13.1 for the majority of the power band.
I was taught that you wanted no leaner then 12.8:1 on an NA car. Accel also recommends this AF ratio on their DFI setups.

Do you think any performance will be gained by fattining it up a few points?

Then when working with accel enrichment, it reads:

Acceleration Enrichment
Acceleration enrichment is a simple throttle transient fuel compensation calculation. Using the change in TPS (TPS delta) as the primary factor, the PCM calculates an Enrichment Fraction. The enrichment fraction is then added to the current commanded fuel. Various modifiers exist to control the rate and profile of the fuel delivery with time, also, other modifiers exist based on vehicle speed etc.

The way I read this is:
Commanded AF: 14.7
then the number in the table with be added to this when accelerating, is that correct?
If so wouldnt that mean it is getting leaner as the numbers in these table are positive?

Also when looking at the DTC's, it appears that the P0301-P0306 codes are all disabled, are these codes compatible with the 3.8?


Second vehicle, 98 GTP

when looking at the PE tables it appears the base AF GM is setting is 12.4:1 and then the add vs. RPM is richening it to 10.8 - 11.2:1 range, am I reading this correctly?

If so, should there be a good improvement by leaning this out to the 11.5:1 or leaner range?

Just looking for some input for those tuning these cars...

[Russ K]

Read this thread over, as it may answer some of your questions.

http://www.hptuners.com/forum/showth...1064#post61064

Russ Kemp

[BTLD_LS1]

Russ thanks for the reply, I actually read that thread over when I started making changes to the Impala a few months back.


Maybe I am missing something or I just need a little clarification as to how the Accel enrichment works, because the way I read it in the help file makes it seem as if its leaning the 14.7:1 out.....