EFI Conversion with
Megasquirt
Megasquirt is the
creation of Bruce Bowling and Al Grippo (may they live long and prosper) who
were generous enough to publish on the web.
Since then it has achieved a life of its own with software, firmware and
hardware contributions from an assortment of very clever people.
Visit the website at www.msefi.com, it is quite an eye opener.
Why Convert?
It has been a long held ambition of mine to convert at least one
of my Triumphs to an electronically managed fuel injection and, possibly,
ignition system.
Originally this was caused by the frustrations of trying to get
the much-tweaked 1300 in my Herald to deliver the goods using SUs or even
Webers and the thought has having an electronically adjustable system seemed
attractive. Also I was hugely impressed by the grunt, tractability, economy and
all-round good manners of our Golf GTI.
Trouble was, that was 15 years ago and I was far too mean (not
to mention poor!) to shell out for a Weber Alpha or similar.
Now it's a different story. The excellent, build it yourself
Megasquirt system has been on the scene a while now and the scrap yards are
bulging with cars to supply the hardware. Should be possible to do it for
pretty reasonable money.
This time the victim is my Vitesse MK 2. The aim is to achieve
improved power, economy and manners over the original (and rather worn)
carbs. If nothing else the choke knob
will be made redundant. Oh, and do as
much as possible myself and spend as little as possible on the way. The modifications should also be
reversible. As I write this, the engine
is standard, well worn (mileage unknown but considerable) but serviceable. Compressions and oil pressure are good, but
it does like a pint now and again.
Tired old 2 litre lump.
Bog standard and well thrashed in. 75A Bosch alternator Fuel Pressure gauge (temporary) Inlet air temperature sensor (beneath) Cold idle valve Injectors Fuel Rail Additional coolant temperature sensor for ECU Fuel pressure regulator Throttle body and position
sensor
How?
Well, as this is a car that was never made with fuel injection,
there are quite a few modifications to be done. This involves quite a few systems and the work involved should
not be underestimated. As high-pressure
petrol and electricity are involved, this is safety critical work.
The picture above shows the under-bonnet modifications – click
on the links below for more information.
How Does it go
At time of writing (Autumn 05) it’s a runner and has been since
May. In fact it goes pretty well. There is room for improvement in the mapping
as, so far, this has all been done on the road, solo using logging
software. This particularly relates to
the cold start areas and the upper reaches of the rev band at large throttle openings. I haven’t touched the map since June and
have done in excess of 2000 miles, so it can’t be too far out! It starts, drives from cold (say 10º
ambient, lower than this is untested!) smoothly. It pulls hard to 4500rpm at about 70% throttle, which is more
than enough for everyday use. Above
this it’s more hesitant. The problem
with mapping on the road is that you can’t spend much time in this area for
obvious reasons! It averages around 31
– 32 mpg in general use and 36 mpg on a long run. This is much more consistent than with carbs. It has been completely reliable.
Mapping will resume once the EDIS ignition system is installed
and I may even cough up for a rolling road session!