Hi all,

I have a Magna TJ Sports 2002 model which I am quite happy with. It drives well but I'm a bit of a lead foot and was wondering whether there is a way to lower the point at which the rev limiter kicks in, mainly for fuel / tire saving purposes. It would be nice to limit the revs to 2k and have a switch to bring it back to the stock 6.5k (or whatever it is).

I understand there are commercial solutions such as this one, which is about $150 + my time:
http://www.amazon.com/Programmable-Ignition-Controller-Mitsubishi-WARRANTY/dp/B004W2W6TA

The above is a plausible solution but the risk of damaging the ECU while desoldering the crystal is relatively high, and then securing wires so that they don't vibrate is another daunting task (usually involves lots of silicone). Not to mention that if I stuff it up that it is about $1k for a new ECU.

I also understand that an aftermarket ECU with dyno-tuning can produce the results I want but it would probably cost $2k+ not to mention not having a car for a few days. I don't really want to spend that sort of money, I have done it before to other cars I have owned and it makes a massive difference to power, but I just can't justify the cost especially since the car is probably only worth about $3k (i.e. engine is A1, but paint job is rubbish).

So, my questions are:

Firstly is there a simple solution to reduce the revs that the rev limiter kicks in? Is there something that I can piggyback on to the end of the ECU to make my own rev limiter?

and, Secondly, if not does anyone have an electrical schematic of the ECU (not the wiring to the ECU, but the internals of the ECU itself). I'm and electrical engineer and don't mind looking through complex schematics.

Thanks in advance.

2k for rev limiter is way too low, car will drive like crap as rev limiter cuts the fuel meaning you will have sudden power cut of at just 2000, it will do nothing to help your fuel consumption and will just make it un drivable.

Be gentle on the throttle that's it.

Next step is to have you ecu reflashed that will help with economy.

Thanks for the reply Andrei.

My reasoning for setting the rev limit lower is to physically stop me from reving the car as much. I was pretty much wondering if there was a cheap way of doing this. But you are right, limiting the revs does not effectively limit the fuel consumption, the trottle can still open fully, so I guess my reasoning is flawed.

I haven't heard of ECU reflashing before. Is that something along the lines of getting the car dynotuned without buying an aftermarket ECU?

how about a switch that controls a light/ buzzer when you exceed a predetermined throttle angle/rpm.... cars functionality remains intact but the light and buzzer will remind you that you are indeed a bad person..... kinda like the speed alert

That is not a bad idea, maybe activate the buzzer with a limit switch that gets turned on when the accelerator is fully down. I've already got the speed alert set low (120km/hr) and it has seemed to stop me speeding excessively so far, well... most of the time anyway.

I'll have to have a re-think. The rev limiter idea has been plaguing my brain for a while, at least I can put that idea to rest.

put a brick under the accelrator

Reflashing of ecu can be done without dyno and rev limiter can be adjusted quite easily, does not cost a lot, where abouts in nsw are you?

Spark map is quite conservative, so adjusting that will give you better power/economy, perhaps tuning for 95 octane would be best in relation to cost/benefit.

Best lower the rev limiter to something like 3,500 rpm if that's really how you want to do it, 2,000 rpm is too low.

BUT why look for mechanical devices, when you already have the perfect rev limiter - the brain which controls your right foot?

I haven't heard of ECU reflashing before. Is that something along the lines of getting the car dynotuned without buying an aftermarket ECU?
More info about reflashing in the thread linked in my signature.

Changing the rev limiter as you've proposed is somewhat akin to a "valet mode" mod I know has been made to Evo ECUs (which use the same microcontroller as the Magna ECUs, and share much of the code) - a mod I hope to tackle sometime.

I'm not aware of any schematics for the ECU PCBs as they're a black box part as far as MMAL are concerned, but if you find some I'd llke copies.

*Changes cars ability to accelerate at pace*

*Encounters a situation on the road where you need to quickly accelerate to get out of trouble*

*Dies*

Seriously.. is self control really that hard? If you want a power restriction to "save tyres", then the cars ability to accelerate is the least of your worries, the problem isn't the car, its the driver.

For the OP it really should be a matter of changing your driving behaviour appropriately.
The first step is to realise there are negative outcomes with your driving style, which you have done already.
Next you need to start carefully controlling your driver inputs and reading the road to anticipate when to slow and accelerate etc.

I'd recommend investing in a defensive driving course/advanced driving course or similar. Having just a rev limiter with a switch without adjusting your driving style, means getting into trouble is always just a flick of a switch away.



Changing the rev limiter as you've proposed is somewhat akin to a "valet mode" mod I know has been made to Evo ECUs (which use the same microcontroller as the Magna ECUs, and share much of the code) - a mod I hope to tackle sometime.

I'm not aware of any schematics for the ECU PCBs as they're a black box part as far as MMAL are concerned, but if you find some I'd llke copies.


However I can really see the value in having a "Valet Mode" available when owning a modified car, and I'd be interested in a mod like this.

buy a BEE-R limiter Pops flames on Limiter :D

Only if your running catless.

Seriously.. is self control really that hard? If you want a power restriction to "save tyres", then the cars ability to accelerate is the least of your worries, the problem isn't the car, its the driver.
Not sure how you'd need to lost power to save tyres with a standard sports in the first place - when my manual ralliart had a standard diff in it i had to deliberately make the tyres spin. Unless i was acting like a dickhead the tyres stayed fine, and if i had a button that set the limiter to 2krpm i would've turned it off on those occasions anyway.

However I can really see the value in having a "Valet Mode" available when owning a modified car, and I'd be interested in a mod like this.

Watch this space... developing a more advanced valet mode for my VR4, which i'll be porting to magna rom.