ECU and questiins
05-01-02, 08:40 AM
#32
Driver School Candidate
Join Date: Mar 2002
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There seems to be some mis-understanding about what the SC400 ecu does. It is much more then just the engine ECU, it also controls the transmission. It also has fallback/failure modes that the piggy back unit probably does not have.
The Mines upgrade does not replace internal circuit boards, it is done in a similar way to the sc400.com upgrade, in that the original micro is removed from the board, placed on a daughter board with an expansion chip and an EPROM. (the board looks very similar to the Techtom mod board for Supra's, not suprising since it is basically the same ECU) This allows customisation of the fuel mapping, and perhaps the timing.
Why the need to play with timing though, I fail to see, as the stock ECU uses the knock sensors to always chose the optimal timing position based on what it "hears" coming from the engine. When pre-dotonation is detected the timing is altered to fire slightly earlier. This tunes the engine for the current fuel octane rating to the engine in the car, as well as the current air pressure and temperature. In fact, the ECU is "learning" all the time. (Training might be a better term.)
As for the Japanese fuel having a higher octane rating, it is because they rate their octane a different way. the fuel is essentially the same for their 98 "octane" as it is for your 92? octane.
The Mines upgrade does not replace internal circuit boards, it is done in a similar way to the sc400.com upgrade, in that the original micro is removed from the board, placed on a daughter board with an expansion chip and an EPROM. (the board looks very similar to the Techtom mod board for Supra's, not suprising since it is basically the same ECU) This allows customisation of the fuel mapping, and perhaps the timing.
Why the need to play with timing though, I fail to see, as the stock ECU uses the knock sensors to always chose the optimal timing position based on what it "hears" coming from the engine. When pre-dotonation is detected the timing is altered to fire slightly earlier. This tunes the engine for the current fuel octane rating to the engine in the car, as well as the current air pressure and temperature. In fact, the ECU is "learning" all the time. (Training might be a better term.)
As for the Japanese fuel having a higher octane rating, it is because they rate their octane a different way. the fuel is essentially the same for their 98 "octane" as it is for your 92? octane.
05-01-02, 12:06 PM
#33
Lexus Test Driver
Join Date: Jul 2001
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The timing has a significant effect because the preset limits for the stock computer are far too conservative. Same with the fuel mixture. With just fuel mixture changes you don't get a very large change (like using an Apex'i SAFC).
10-20-02, 07:21 PM
#35
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We've moved onto using our re-tunable ECU for tuning the new turbocharger system. I'm not sure what they're doing with the SC400.com one anymore... I know the owner moved on and dropped a 2jz-gte in a SC300, and I have a pair of T3's on order...
"-ACleanSC4
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