[s-cars] RS2 MAF deliberations

[Robert Pastore]

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Todd:

I agree with you, except that WRT the FPR. Both the Hoppen/Lehmann and my
"favorite" rs2 chipset were written as "rs2 in AAN" as opposed to "NATIVE
rs2".   Through the same kind of testing you just despcribed, I have found
that they both run better with the stock AAN 4.0 bar FPR instead of the 3.8
bar rs2 unit.   I have even tried adjusting the value of r201 in the ecu to
the rs2 value to see if these were really "NATIVE rs2", thinking that the
adjustment it woudl cause in the MAF signal would cthen result in an "match"
with the lower rs2 fuel pressure.  I didn't work, so the conclusion I drew
was that the internal labels on the chip that showed a 551AA ecu (i.e. AAN)
were telling the truth, and the FPR wasn't part of the assumed hardware set.
Again, it all depends on the HW assumptions the programs were written for. I
have yet to find a chipset that ran better with a mismatched MAF and
injector set, so I tend to agree that these should be viewed as a "set",
i.e. (rs2 maf + rs2 FI), (AAN MAF + AAN FI).

Bob

-----Original Message-----
From: TODD KRAMER [mailto:toddekramer at msn.com]
Sent: Thursday, April 17, 2003 7:11 PM
To: s-car-list at audifans.com
Subject: [s-cars] RS2 MAF deliberations


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Fellow S-listers, my experience:

Test Mule:
1995 S6:

RS2 Turbo K26hot/K27cold,
RS2 Exhaust Cam
RS2 Injectors
RS2 FPR
RS2 MAF

Lehman RS2 Software
2.5 Bar Boost MAP

During my build, I came across an RS2 MAF at a good price and put it on my
ride before I upgraded to RS2 Fuel Injectors and Fuel Pressure Regulator
(fuel delivery "set").  My A/F meter ran really rich under overboost but
bucked and hiccupped as if the O2 sensor and the MAF were playing tug of war
with the mix.  My diagnosis, the MAF is metered for the proper injector
regulated by the proper FPR.  Once those parts were upgraded, the car ran as
expected.

To test my theory, because of this thread, I swapped my old MAF into the RS2
setup and found the car ran lean . once again, the MAF was not calibrated
for the injector/FPR setup.

More air gets more fuel until the O2 sensor does not like what it is tasting
. then the ECU tries its best to keep the damn thing from blowing itself
up.The electronic signals from the MAF are paired to the flow rates of the
associated injectors the ECU is expecting.

So . without boring the audience with measurements of wire diameter or
plastic thickness processes, my recommendation is upgrade the fuel delivery
system as a set (MAF, Injectors, FPR).

.and all because I stayed in a Holiday Inn Express and chose to check my
email.

Todd Kramer
Salt Lake City (5700 feet)

1995 S6
1995 Cabriolet

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