To kick this one off – why go to fuel injection?

Well, the answer is in three parts really.
The first is that I was never 100% happy with the Zetec on carbs. I’m sure that with lots of playing around they could have been made to work. The problem I believe was all down to the progression phase of the fuelling. The carbs were fine on the x/flow and I believe that the main difference is that a 16v engine requires the main jets to be brought on earlier than an 8v engine. You can have an extra progression hole drilled in each chamber of the carb and if I had been staying with carbs I may have tried this. This problem manifested itself as a hesitation to pick up from lower rpm giving a very much two stage engine feel – cruising or blatting.
The second part is that the trouble with carbs compared to fuel injection coupled to a re-programmable ECU is that to make any changes to the fuelling you have to have another set of jets to hand, and these will then most likely effect another set of jets. The quickest way is to book a rolling road and spend a while checking different combinations – which costs. Before this modification I didn’t realise, or rather appreciate, the ease of making a fuel correction sitting at a laptop in the garage, or at the side of the road. I had reached a point where I wanted a bit more power, which may have just been linked to the first parts above, drivability, but more power is always nice – you don’t have to use it. Right? Anyway, the next stage to more power is to fit some up rated cams, which in turn need a ported head to deliver their potential (both of which I will get to later). The higher flow of air means you need to supply more fuel, which would need loads of time spent of a rolling road. The ECU allows you to adjust this on-the-fly. Brilliant. The carbs would have limited the flow of air as they were only 40’s which I felt were already limiting the engine.
So, to summarise, fuel injection allows easy adjustments of the fuelling to match the needs of engine, whether tuned or not. This meant that I could up rate my cams and fit a ported head and tweak my fuelling to suit. It also allows much finer control which means you can run a larger choke size, which gives more power, but you don’t suffer the torque reduction you would with carbs. The final reason, which doesn’t really relate to how the engine performs is that with the Gems ECU that I had running the ignition with the carbs, the car was unreliable starting. I had tracked this down to the way that the ECU read the crank position sensor. It basically didn’t seem to wait long enough to fully determine where the engine was, which meant that it would fire too early, with the engine not fully up to cranking speed and it would stop dead. I had fitted a work-around switch which allowed me to spin the engine before firing up the ECU, which would then fire as soon as it saw the signal (I rarely used this, it was just a backup plan for my peace of mind).

So, how to go about it? I had a few things to decide. The first was obviously what to do – how far to go with things, what would everything cost, what would give me what I wanted – a drivable engine with good power and torque.
The power side of things would dictate the rest of the project, in terms of what I would need, so it was the best place to start. I knew from a friend, Brent, that Piper 285 cams and a ported head would give around 200bhp. His engine remained tractable which I wanted. I toyed with the idea of fitting Kent FZ2002 cams, which are of a similar spec to the Pipers, but decided to go with those so I could tap into the knowledge that Brent had gained during his upgrade. I then needed a ported head – for which I already had a plan. I had bought a spare head from a friend of Brent’s a year previously. I had done so with the intension of having a go at porting it myself. This I chickened out of, plus my work went chaotic and I didn’t feel that I would have enough time.

Next I would need a pair of throttle bodies. For these I had only two options, the first was the easy option of Jenvey DCOE replacements. These simply bolt in place of the DCOE carbs, onto the same inlet manifold. The other option is to take a pair of modern motorbike throttle bodies, which are typically individual, and fabricate / modify an inlet manifold to suit. The throttle linkage would also require some work to make sure they all opened together and could be balanced. Needless to say, I took the easy option. The main one was, again, time. I think it would have been quite good fun to make everything for bike TB’s, but my time was too limited to consider this. The other reason is that the Jenvey TB’s look great – they are even the same colour as my cam cover.

The last piece of the puzzle was the ECU. For this I didn’t take the easy option! This would have been to buy an off the shelf, the favourite being an Emerald. The Emerald was designed to replace the Rover Mems ECU of the K-series engine and simply plugs straight into the same connector. Job done, other than mapping it. For my application I would need to make, or get made, a loom to connect it to the car. The option I took instead was to go for a DIY ECU called Megasquirt, or MS. This is an open source web based project that started life several years ago in the US. The basic premise was to design a unit which would be fitted to almost any vehicle and could control a fuel injection system. It started out as simply a means to add fuel injection to your carb fed engine. The unit would take an ignition pulse from a distributor and determine when to fire the injectors. The other task it could perform was to replace a current injection control system with one which the user could then re-program. I suspect that the latter is now the most typical use, as most cars are now FI to start with. The unit is incredibly flexible and project examples range from 4 cyl cars, high revving bikes, V8’s and rotary’s. I have even seen someone claiming to have fitted it to a single cylinder Briggs & Stratton lawn mower engine! The problem is that as cars have become more complicated and most ECU’s now control both ignition and injection in one. To cope with this the MS has a number of off-shoot projects which utilise the core design but which add various ignition control methods, usually using some standard manufacturer’s module. This is precisely what I have gone for. The project I initially picked was called the MS’n’EDIS but this was merged with a couple of other projects to form the MS’n’Extra code variant. This would give me the ECU’s normal control of the FI and also a signal to drive a standard Ford EDIS ignition module and wasted spark coil pack (both of which were used on Zetec Escorts and Mondeos as well as some late CVH engined cars). This system was perfect for my car – as you will have spotted the Zetec word mentioned – it was almost designed for my set-up.
Another key selling point is that you can tune it yourself if you have a suitable lambda EGO sensor (Exhaust Gas Oxygen). This gives a readout based on the exhaust gases and will tell you if you are running rich or lean. The preference is for a wideband sensor over the narrow band flavour as this specifically tells you what you have as a figure whereas a narrow band can only say if you are rich or lean, not by how much. Pump gas fuel gives an ideal lambda reading of 14.7:1, known as stoichiometric, but for power you want it richer than this, between 12.5 and 13:1 for a nasp engine. Having it richer also prevents the engine getting too hot as the slight excess of fuel helps to cool things down. The MS ECU can take an input from the wideband sensor and use it to adjust the fuelling.
It can also data log all of the input channels to a laptop and this can then be used at a later date to determine changes to the fuelling map. The tuning cycles is therefore determine a starting map and go for a drive, interpret the results, adjust map, go for a drive… and so on.
Oh, and the DIY thing – you have to solder all the components onto the PCB yourself, make the loom, create your map and try to get it working…

So there we go – the decisions made, next was to put it all together, in some kind of order and get it working.

NOTE: I have since changed the ECU to an Emerald due to various issues with the Megasquirt but have decided to leave te information here for anyone looking for information. You can read about the Emerald swap here.

Porting the cylinder head
Having a Lambda boss welded on my 4-1 collector by my good friend Steve.
Porting the inlet manifold to match the throttle bodies and ported head
Assembly of the DIY engine control unit
An added bonus of the ECU - shift and warning lights
Wiring loom to mate engine and ECU.
Throttle linkage for the new throttle bodies
Manifold air pressure sensor take off mounting on the inlet manifold
Fuel tank is swapped for 'built-in pump' type
Fuel regulator to maintain the fuel pressure for the injector fuel rail
The fir run of the engine with the new ECU and injection
Swapping the head and then cams for the 'more interesting' versions
Running the new cams for the first time
New filter - nothing is ever straight forward.
Mapping the engine took longer than expected
A few nice shots of the finished engine bay.


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