1227165 Tuning Advice

[David A. Cooley]

>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.


That's the norm...

>
>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
>

The computer doesn't pull fuel at WOT... the BLM and INT values jumped back
to 128 so it's using the values in the PE tables to set A/F.  The ASM chip
is probably somewhat "generic" for a hopped up 305... you're running a 355,
so you have more cubes to feed, plus, if the cam is larger or the engine
breathes better than what they figured for the chip, then WOT will be lean
as it's not looking to feed that larger airflow with fuel.


>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.


It doesn't or the BLM and INT at WOT would jump to something besides 128

>
>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.
>

This follows the values you showed previously... too much fuel everywhere
except WOT...


>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.
>

Depends on the Fuel pump, regulator and injectors...  If the FP has the
volume to run at higher pressure, then the limit will be max pressure
designed into the regulator, or the injectors functioning properly if the
pressure get's to too radical of a pressure (usually 70psi and up starts to
affect injectors).

>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 ???? Does this table use "Load" or "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!


That means the chip is giving too much fuel at part throttle/light
throttle...


>
>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.
>

Bruce,
The FP being cranked up is just to see if the WOT detonation subsides...  If
it does, set the FP down to where the cruise/part throttle BLM's are closer
to 128 (maybe down to 37-38 psi) and add fuel in the PE VS RPM table.  If
you can get the car to stay in 2nd gear at lower RPM's, 2nd is a good place
to record a full run and watch the fuel all through the RPM range at WOT to
adjust the PE vs RPM.   My little 3800 V6 PE vs RPM is adding up to 10.5% in
PE vs RPM so it can take quite a bit to get the fuel up.