eharleq@selway.umt.edu wrote:
>> I would say that
>> removing a fuel cut based on air flow would be legal under the first
>> sentence of 14.10.C "Carburetors, fuel injection, intercoolers and
>> intake manifolds are unrestricted."
>>
>> Mac Crossett
>> '96 Eagle Talon TSi AWD #49ESP
> NOTHING in 14.10.c says removing a fuel cut is legal. It describes
> essentially plumbing changes, not specific control changes.
Actually, Mac's right here. 14.10.c allows changes to fuel injection,
specifically the airflow/injector duty cycle maps that control air/fuel ratio in
the ECU.
It just so happens than in the very specific case of the Talon, the air/fuel
ratio maps specify 0% injector duty cycle at airflow values over a certain
amount - effectively cutting off fuel flow. If one were to change those maps to
allow more than 0% injector duty cycle at these airflow values (perfectly legal,
this is the essance of the standard SP "chip upgrade") then fuel cut has been
effectively removed.
IF a given car instead had specific logic that said "at airflow value > x, open
wastegate fully" or "at manifold pressure > y, cut fuel" then modifying that
logic would be illegal.
Now it is a reasonable assumption that the reason WHY the fuel maps go to 0% on
a Talon over a certain airflow value is that: because the Talon ECU has no
concept of boost, that Mitsu picked an airflow value that they were reasonably
certain no stock Talon would ever see unless there was a massive overboost
condition, and zeroed out the fuel maps as protection against that (potentially
fatal) overboost condition. That would make it a "boost control" by intent.
It is _also_ a reasonable assumption that Mitsu figured that there was no way a
stock Talon would see that level of airflow _ever_, and so saved a little money
by not calibrating the A/F ratio for that operating range. Or, it could be a
defence against a faulty airflow meter, or a defence against running the
injectors out of fuel flow capacity (and so running lean and detonating -
incidently, this is why _I_ think it's here, as the stock DSM turbos are too
small to _ever_ produce destructive overboost) Any of these would make it not a
"boost control", but instead a fuel injection control parameter, and thus fair
game for modification.
Whatever the reason is, the shop manual makes no mention of a fuel cut, so
there's no official way of determining the "intent" of the manufacturer. One
could make the case that it's not realy there. "It's just a really weird fuel
map".
It's legal - IN THIS SPECIFIC CASE - as it is no different than modifying the
fuel map in any other SP car.
Incidently, it's also a moot point. The airflow value that it takes effect at is
so high that you have to be at very heavy load on a very cold day for it to
happen - it's hit me exactly once, and never under racing contitions - that
there's really no benefit to removing it. I still have mine.
DG
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