this thread is full of fail!!!
people completely ignore the facts as to why this shouldnt be done.
people completely ignore the facts as to why this shouldnt be done.
ECU rev limit crystal modification.
- Thread starter SuprAng
- Start date
amichie;1290446 said:
I have modded around 100 3000GT/Stealth ECU's with great results.
The mustang guys used to do this before there were chips for those cars.
Just raise the crystal frequency 10-20% and re-tune.
It appears that some Supra ECU's have more than one crystal, I think they all should be overclocked by the same % unless there is informatuion to the contrary.
B
Good luck with this.
The following sensors are sensitive to the internal ECU timebase:
AFM,
vehicle speed,
RPM,
although not obvious, also all A/D sensors (water temp, air temp, voltage, TPS, oil pres, internal reference) will be scaled due to the way data is transferred internally from A/D).
Internal 1 MHz serial comm will also be scaled between certain chips, possibly leading to data errors.
The following sensors are sensitive to the internal ECU timebase:
AFM,
vehicle speed,
RPM,
although not obvious, also all A/D sensors (water temp, air temp, voltage, TPS, oil pres, internal reference) will be scaled due to the way data is transferred internally from A/D).
Internal 1 MHz serial comm will also be scaled between certain chips, possibly leading to data errors.
^^ and that right there would be the final word IMHO since he's been trying to decode the ECU...
3p Thanks for the final verdict.
I knew that the timing had to affect just more than RPM. though no facts until now
I knew that the timing had to affect just more than RPM. though no facts until now
There is also another crucial area it impacts that I forgot to mention, which is injector duration.
To fire an injector bank, the ECU computes the duration in microseconds and loads a timer interrupt counter. The timer clock is supposed to be exactly 1 us, so that the computed duration loaded into the counter is exactly the duration in microseconds.
Scaling the timebase will directly scale the injector duration, so a 20% increase in crystal frequency will results in a 20% decrease in injector duration. The fuel trims can compensate for some of this during closed loop calibration, but as we know, a 20% offset in the fuel calibration is a huge trim.
To fire an injector bank, the ECU computes the duration in microseconds and loads a timer interrupt counter. The timer clock is supposed to be exactly 1 us, so that the computed duration loaded into the counter is exactly the duration in microseconds.
Scaling the timebase will directly scale the injector duration, so a 20% increase in crystal frequency will results in a 20% decrease in injector duration. The fuel trims can compensate for some of this during closed loop calibration, but as we know, a 20% offset in the fuel calibration is a huge trim.