Originally Posted by charliex
1. Will a slightly smaller SC pulley require tuning to be effective? Won't the MAF signal reflect the increased airflow and the ECU adapt by increasing fuel delivery? Is the MAF capacity or the injectors near max capacity for the stock configuration?
No, the math would have to be identical or it starts to drift, a couple of people have tried it but i don't know of anything thats confirmed as a success, you'd need a way to be sure it was following the right breakpoints, if you could do that then the MAF tube is feasible, but it wouldn't change that with a smaller pulley you're increasing fuel pressure across the injectors. However if you did make the breakpoints follow the same mapping, i don't really see the point, since the spark/AF would be the same as stock, more air would require more fuel, unless you're just going off the 'lean is mean' theory.
2. Has anyone tried porting the blower? Maybe the newest versions of the M62 already include the porting that Magnuson was offering a few years back but when I had my blower ported it was worth about 10 degress lower IAT (improved blower efficiency) at full boost/load.
i've heard of people doing it, but i have no experience with it, i've heard mixed results.
3. Does the ECU really compensate for the mods like improved intake air flow or exhaust flow? I've read several threads indicating that the ECU eventually learns to cancel out such mods for open loop operation. This is counter intuitive to me as all the ECU strategies I'm familiar with are intended to allow the engine to benefit from better breathing. Some engine management systems are limited in their ability to take advantage of improved air/exhaust flow due to the capacity of the MAF, injectors, head flow characteristics, A/F ECU maps, etc. But, I've never come across an ECU with a strategy intended to counter improved airflow.
i wrote up an explanation of why it happens, and included pictures of the loop as to what goes on, though i'm not sure where i posted it, but its on one of the hundred or so threads with the same question.
its a feedback loop, garbage in, garbage out , and with an adaption capability, it'll drift.
It's not designed to counter it, there just aren't enough sensors or feedback information for it to be able to correctly retune for it and get the data it needs to adapt properly, its all based on fixed fuel pressures, particular air flow etc. cars that can retune for it sucessfully would have things like widebands instead of narrows, fuel pressure sensors etc.
if the MAF reads too much or too little air, it puts it on the wrong breakpoint row, the fuel mix is wrong, the Base AFR could be wrong (its a smaller resolution map) so in turn it attempts to adapt for the wrong settings.
You also have to be able to define 'improved' in the context of the engine itself, its really only going to get better if its suffering any to start off with, or if you think running leaner would add power.
4. Is the ECU tuning out a mod more of a problem for closed loop operation vs open loop operation?
not in my experience, so far i only know one person that says he's been able to sucessfully use a piggyback, lots have tried, part of the problem is turning off the adaption or adapting to it.
4. In one thread, I read that the Exige S ECU uses a constant for fuel pressure rather than picking up a value off the injector rail. Is this true?
yes, not just the S, all of them, there is no fuel pressure sensor,so thats the first problem.
5. Are there tuning tools available to "tweak" the stock ECU to allow changes to A/F in open loop operation, ignition timing, etc. short of complete replacement of the control system (e.g. EFI)?
i have mine, but its not on general release, i know of no other outside of the OEM.
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