aftermarket ecu for mpi cars?
Turbo Mini Forums

Hi, I have just built a fast road engine for my mpi cooper. I will be fitting this to the car when I have some time off in the next few weeks.

What bothers me though is that after all of the work and cost and time of building this engine, it will only be circa 80-90 bhp.

Im new to the world of aftermarket efi, and the terminology/just getting my head around the principles is mind boggoling to me. I have red, re-read, and still am having trouble understanding.

Basically I would like to run a na engine in my mpi car, probably with megasquirt (is this advised?), also are the mpi sensors etc compatible?

I am amiss to which inlet manifold I could use? Would standard mpi be ok?

Im fairly mechanically minded, but is the whole aftermarket injection ultra-complicated, or is it something that can be achieved on a limited budget by a home mechanic?

Sorry for such a beginner spec post :/

Any advice/pointers in the right direction greatly appreciated. Thanks

It would be entirely feasible to use the MPi manifold etc with an aftermarket ECU. I'm not sure that it would give you heaps more power, but it would allow you to optimise the fueling and ignition.

You could use the Canems ECU which is a simple semi-sequential system.

But you could use a Megasquirt ECU and the TurboMinis.co.uk developed Siamese Code, that is now part of the mainstream MS2/Extra v3.0.3 code. I'm obvioulsy biased, but if you want to achieve the best then the Siamese Code is the way to go.

There would need to be some adaption of the MPi kit to the Megasquirt:

The manifold, injectors, fuel rail and throttle body should be fine.

Coolant and air temp sensors would work fine. The Throttle position sensor should also be OK.

The MS uses an onboard Manifold Absolute Pressure (MAP) sensor, so the MPi sensor fitted to the manifold can be removed and a tapping taken of to connect the MS.

The Inlet Air Control Valve (IACV) would need to be swapped for one of a Peugeot/Citroen. This does the job of the choke in letting more air in when cold.

The crank position sensor should be OK. There is an implementation of the MPi crank tooth arrangement in the code, but not fully tested. You could convert to a 36-1 toothed crank wheel.

You could also use the cam sensor, but you will need some additional circuitry to handle the sensor as it is a Variable Reluctance (VR) sensor. Conversion to an optical or Hall sensor would be simpler.

The Rover coil pack could also be used or substituted by a Ford item.

The Megasquirt itself just needs a standard build with the MS2 daughterboard but with the addition of the cam sensor circuit.

You will need dual wideband sensors to set it up.

The setup is straightforward. It is the same as any EFi system, but with the additional tables for injection timing.

It's not simple, but if you like a challenge, then it could be very rewarding.

Good luck.

Edited by Paul S on 1st Nov, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

As above, but I too am biased.....

However, you also need to consider what emissions standard you will be tested to. Presumably it will be the later ones - although you are allowed to claim the standards applicable to the year of the engine, not the car, it would be hard to argue it was an early engine if it has multipoint fuel injection fitted.

The point being that, apart from the MPI system itself, only Jean's code on the Megasquirt can do sequential injection with timing offsets. The others are either only semi-sequential (Canems) or sequential without offsets (VEMs etc) so may not be able to meet the standards for emissions on a 5 port head.

This wasn't the reason I went down the Megasquirt route, I get the lower emissions standards anyway, but it's worth considering - if you were interested in Canems for example, I would ask them for documented proof....

Schrödinger's cat - so which one am I ???

Good point about the emmissions Rod.

I had my '92 car MOTd in September and it passed the Non-Cat test, but not by a huge margin.

As long as you retain the cat you should be OK with the Megasquirt/MPi system.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Sorry to Hi-jack but something thats been on my mind is the MPI system, i'm planning on building a 1380 turbo engine with cam, head work, T3 etc, would it be worth while (for more power really) to run MPI with the megasquirt management or am i just aswell to keep it carb'd?

'89 Austin Metro GTa :)

Assuming you mean all the MPI engine parts but swapping the ECU for a Megasquirt, most of the answers are above, the only immediate additional consideration for 1380 and turbo would be injector size. I'm not sure what size the MPI ones are (Paul will answer that I'm sure) but they will be the power limit. And it's not just a case of putting bigger ones in, although possible, as you would start to lose control of idle. So the answer is then staged injectors and that means new or severely modified manifold.

And bear in mind so far in the UK (as far as we are aware) only Paul has this up and running in a car, and I have it up and running on an engine (car not quite finished yet) but neither of us have implemented the staged injection yet although we are close.

However, it would be great to see more people joining in.

Schrödinger's cat - so which one am I ???

I think the actual answer is no, not yet. And even when the staged injection is fully sorted, it's unlikely to provide more power, but it will provide better economy and potentially improved throttle response.

If you want more power for little work, bin the T3 and get a modern turbo. Look at the thread on the RR day, see what power a GT17 engine produced compared to a T3, or T2 (for the same boost).

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk