Re: IA prices

[zm@mhcnet.att.com (Zafer Mehmood [209])]

> Does anyone really understand what Ned is doing? If he's just extending the
> max boost shut-off point from one value to another by changing some values
> in a rom look-up table, why doesn't he just give you the max safe boost in
> stage I? For another $795 I'd expect something more than an upgrade from
> sub-optimal software to optimal. No flame > Ned intended, just wanna know
> if there's more to stage II than different numbers in an eprom.
> 

The reason Ned has Stage I and Stage II both at the same list price ($795)
but doesn't automatically give max boost (2.0 bar) is that
you have to use 92 or higher octane gas with this level of boost. This
was explained to me by Ned. Apparently, 92 (or higher) octane gas is not
available in all parts of the country. Ned mentioned that 90 is the
max octane you can get in, say Montana. So, he has two separate EPROMS
and recommends one or the other based on where you live.

Higher octane gas essentially has a higher anti-knock index (ability to
resist pinging or knocking/detonation). With higher boosts, knocking occurs
more easily. Prolonged knocking will destroy the engine. Normally, the engine
ECU detects knock and dials back (retards) the timing to avoid or reduce
knocking. According to Ned, the Audi ECU is capable of a max timing dial-back
of 7.8 degrees. So, if you are running high enough boosts or low enough octane
to exceed the 7.8 deg retard limit of the ECU, then you run the risk of
damaging the engine. The timing maps that Ned puts in the Stage I or II
are appropriately selected to give you safe operation at the max
allowable boost level.

People who buy the SuperChips or TAP computer mods or do their
own home brew solution for increasing boost have to keep in mind that some
of the safety features built into the system by Audi are being defeated.
>From previous discussions we've had about Superchips and TAP, both these
mods only defeat the max boost limiting feature of the original ECU but
do not change the PROM maps to dial back timing or prevent the engine
from running lean (though at least one of these companies swaps the PROM
but with the same contents!). 

charlie@elektro.cmhnet.org (Re: 5kCSTQ - Free Horsepower (almost)) had
written about how he replaced the wastegate spring with a stiffer one and
defeated the the fuel pump shutoff mechanism. Although replacing the stock
spring with a slightly stiffer one is fine, I'd be wary of putting in too
stiff a spring because you might end up defeating the whole purpose of
the ECU controlled wastegate. The ECU uses vacuum on the other end of the
wastegate diaphragm to modulate the max boost pressure. If you use a very
stiff spring, the vacuum may not be able to overcome the increased spring
tension. Also with the fuel pump shut-off mechanism defeated, no changes
to the timing map to change timing, you have all the ingredients to
cause uncontrolled boost -> detonation -> engine blow up. One has to
be careful and aware of the potential risks.

I too was tempted to make the modifications myself rather than spend
the money on IA. But after investigating into the whole thing and all
the discussions we've had on this list about TAP problems, blown intercooler
hoses, etc, I decided to go with IA. I now have the Stage II on my car
and am very happy with the results. I'm also impressed with Ned's
knowledge, willingness to help and professionalism with which he
handled the whole transaction. Also, I looked at the innards of the computer
before and after the mod. Impeccable soldering job on the PROM. If I
hadn't jotted down the number on the PROM before sending it out, I couldn't
have detected it had been replaced! Also, the IA mod is 50-state emissions
legal including Certification from California's stringent CARB.

Usual disclaimer: I have no affiliation with IA other than as a satisfied
customer.

Zafer
'87 5KTQ IA Stage II.


-----------------------------------------------------------------
Zafer Mehmood				   AT&T Bell Laboratories
zm@mhcnet.att.com			   Murray Hill, NJ