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Hello I've been thinking about doing the ECU mod (changing the crystal) - and I wanted to know what you think about it?
As far as my opinion is concerned CAI + No Cat. exhaust move the maximum power/torque to the higher values of engine rotations therefore rev limit. should be changed as well...
Looking at the dyno results from serial mx-3 (it's my friends - awesome results just as factory manufactured it) http://img515.imageshack.us/img515/1350/dsc0334d.jpg" onclick="window.open(this.href);return false;
we see that the HP is growing till the end - so probably the power will keep on rising together with rotations - and as we know for example mx-5 1.6 dohc enginge car survive up to 9000rpm without any big problems.
On the other hand many people claim that after Rev limit is reached in mx-3 there is a sudden drop of power - and that CRYSTAL mod leans the AFR mixture... which is not that good...

Finally I have a small question - in mx-3 online manual - ECU is called ECM or am doing a huge mistake?:)

Modifying your ECU is a bad idea. That will not raise your upper rpm limit.
The miatas have solid lifters and different camshafts to accommodate the 9000rpms,
they were designed to do so. Your 1.6 B6 was not designed to do so.

Engine Control Unit = Engine Control Module
ECU = ECM

Mi|<E wrote:That will not raise your upper rpm limit.

?? How come?? It is said that the bigger the crystal the higher the rev limit - like 4,2 crystal in place od 4mhz (that's what I want to do) will increase the rev limit from 6900 to 7331 (which should not affect the engine in any way and should not lean the AFR that much) ...

get a power adder instead of messing with your rpms. Have you not noticed that you really don't go throught the rev's all that fast? Unless you have enough tq to break the tires when you shift, you are crazy.

Its redline is 7k for a reason - the hydraulic lash adjusters collapse and don't do what
they are intended to above 7ish thousand. Miata's which can reach 9k rpm have solid lash
adjusters which do not collapse under high revolutions.

uh...miatas DONT have a 9k rev limit... we top out at 7200...although our internals are not quite the same. we have lightened crankshaft and flywheels to help improve acceleration and vibration at higher rpms, along with a wasted spark ignition, although the latter might have have litle with the whole thing.
i have added corksport's webcams and a piggy back computer along with bigger injectors and got it up to 7.5k, but it's not recommended. now, with a properly tuned ECU (be it ms, emanage, or AEM's) you can go as high as you want. it helps to have bolt-ons too. MX-3s start dying off at like 6.5 because our headers can't handle the ammount of exhaust flow. get some bolt-ons on your car and it won't die off as quickly. trust me.