I wonder, why some chips have different programs for different fuels (octane)? (m)
12-17-2002, 02:40 PM
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I wonder, why some chips have different programs for different fuels (octane)? (m)
Isn't the ECU an auto-adaptive system? Doesn't the ECU measure intake air mass flow, boost, detonation onset, exhaust gas temperature, and many other parameters to automatically optimize the complete range of performance according to the environment, including octane rating? That's what the ECU is all about in the first place. The S4 is sold all over the world where climates and octane ratings vary greatly. Do they get a different ECU for every country? Hardly.
Last summer, a friend inadvertently filled 87 octane fuel in his S4 (stock 551M ECU). Max power appeared to be down, but the car ran perfectly otherwise. Later, he treated himself to 100 octane racing fuel at the track and found himself staying with cars on the straight that had left him behind in the preceding sessions. Surprising? Hardly.
The ECU uses complex proprietary algorithms to integrate real time sensor input and feed back with many preprogrammed data maps to optimize performance. IMHO, to change its performance envelope properly, you need the proprietary source code. Just doctoring the data maps or biasing certain settings would upset the system's integration, producing, perhaps, more peak power, but also creating some seemingly unrelated glitches. Yet, some (nameless) chip makers told me that they have no other choice, because they have neither the resources, knowledge, or time to reverse engineer the source code, and to do the extensive verification testing throughout the complete performance envelope, after the ECU was altered.
Where am I going with this? I know of two (nameless) tuners of whom it is said that they have at least access to the proprietary source code. Their chips don't offer different programs for different octane ratings. But, in actual use, their chipped ECUs seem to perform as well, or better than some of the hottest other offerings that claim questionable power increases but stumble through normal operation.
We are gullible to believe the most aggressive promotions because we wish them to be true. :-)
(Before anyone feels like flaming, remember that it takes documented, rigorous (normalized), and repeatable testing to really prove any comparisons between chips.)
Happy holiday motoring,
Last summer, a friend inadvertently filled 87 octane fuel in his S4 (stock 551M ECU). Max power appeared to be down, but the car ran perfectly otherwise. Later, he treated himself to 100 octane racing fuel at the track and found himself staying with cars on the straight that had left him behind in the preceding sessions. Surprising? Hardly.
The ECU uses complex proprietary algorithms to integrate real time sensor input and feed back with many preprogrammed data maps to optimize performance. IMHO, to change its performance envelope properly, you need the proprietary source code. Just doctoring the data maps or biasing certain settings would upset the system's integration, producing, perhaps, more peak power, but also creating some seemingly unrelated glitches. Yet, some (nameless) chip makers told me that they have no other choice, because they have neither the resources, knowledge, or time to reverse engineer the source code, and to do the extensive verification testing throughout the complete performance envelope, after the ECU was altered.
Where am I going with this? I know of two (nameless) tuners of whom it is said that they have at least access to the proprietary source code. Their chips don't offer different programs for different octane ratings. But, in actual use, their chipped ECUs seem to perform as well, or better than some of the hottest other offerings that claim questionable power increases but stumble through normal operation.
We are gullible to believe the most aggressive promotions because we wish them to be true. :-)
(Before anyone feels like flaming, remember that it takes documented, rigorous (normalized), and repeatable testing to really prove any comparisons between chips.)
Happy holiday motoring,
12-17-2002, 03:00 PM
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Neuspeed seems to adapt very well between 91 and 100 octane....
they do offer 1.1, 1.2, 1.3 bar programs, but you have to have the ECU re-flashed to get these....not switch on the fly.
12-17-2002, 03:16 PM
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Yeah, it looks like GIAC and APR sure do have "questionable power increases" on either programs.
<ul><li><a href="http://www.s4biturbo.com/timeslips.cgi">http://www.s4biturbo.com/timeslips.cgi</a</li></ul>
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12-17-2002, 03:26 PM
#10
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i think those slips prove VonK's point. what are the top times?
GIAC XR (Dedicated Race program)
Abt
APR Race
All on high octane fuel. Do we see a GIAC X chip or APR 91/93 Octane chip on high octane up there? Why didn't the Abt user (piggie) have to change to an Abt Race chip. For one, it doesn't exist, and for another, he didn't need to. The chip adapted better than GIAC regular program.
Of course, this could be a self-fulfilling prophesy as the GIAC/APR group has already armed themselves with the race programs and are using that exclusively at the track.
Driver/car differences can be accounted for because two almost identical times are Piggie w/ different ECU's (Abt vs GIAC XR)
Abt
APR Race
All on high octane fuel. Do we see a GIAC X chip or APR 91/93 Octane chip on high octane up there? Why didn't the Abt user (piggie) have to change to an Abt Race chip. For one, it doesn't exist, and for another, he didn't need to. The chip adapted better than GIAC regular program.
Of course, this could be a self-fulfilling prophesy as the GIAC/APR group has already armed themselves with the race programs and are using that exclusively at the track.
Driver/car differences can be accounted for because two almost identical times are Piggie w/ different ECU's (Abt vs GIAC XR)