Started - October 2008

The GTS is taking a step into the 21st century and being fitted with Fuel Injection this winter.

I will be using a Megasuirt ECU and GSXR 600 throttle bodies for the conversion.

ECU

I have decided to use the Megasquirt system for my fuel injection conversion. This is a DIY system which is incredibly well supported online, both in the UK and the USA. The system was originally designed by a couple of guys in the USA and has been developed significantly.

I am running a MS1 Extra system, controlling fuel only. (There are options to include spark and a whole whost of other stuff too)

The website can be found here

One of the UK distributors is Extra EFI

I bought the system second-hand but unused. The loom I built myself, a fiddly job, but pretty easy really. The connectors are readily available, I bought a pack from RS (part # 375-2293)

Lamda Controller

This is a must for EFI tuning in my (and many others) opinion. I as lucky in that my ECU came with an Innovate LC1 wide-band lamda controller and sensor. I don't have any pics as I have already fitted it to my car, to give me a constant AFR (air-fuel ratio) read out on my AIM MXL dash. This tells you if you are running rich or lean at any point in the rev range. It can also be used for auto tuning once you get the map somewhere about right.

Throttle Bodies

 

I decided to use GSXR 600 throttle bodies. They are individual throttle bodies, which means they can really easily be respaced. I made some spacers up from some stainless tube I had laying around in the garage.

Because I respaced the throttle bodies I needed to extend the throttle arms between them, this was simply done by TIG welding some extensions on. The TBs have been spaced to suit the standard weber carb spacing (90mm centres with 105mm between the centre pair (this varies on different engines!)).

I also needed to make a new fuel rail. I bought some billet blank from Ross Machine Racing It was $10 per foot, a damn sight cheaper than Demon Tweeks. They sell on ebay and are happy to ship to the UK (took 5 days). I machined this at work to suit the new injector spacing.

I also decided to be a bit different and retain the standard DCOE manifold and machine some adpators to mount the throttle bodies. I dislike the fabricated manifolds, especially those which retain the standard TB spacing, they are far from optimal due to different intake lengths.

For further info this is the spec of the throttle bodies:

Inside Diameter: 38mm
Center-Center (left to right from behind): 80-80-80mm
Overall Length: 83mm
Outside Diameter (intake): 44mm
Outside Diameter (filter): 45mm
Separate casting: Yes
Injector Make/Model: Keihin KN4, 0J07 AAA A
Flow Rate (45psi/100%): 240cc/min, 13O

As standard the throttle bodies have a lot of electrical gubbins on, including a set of secondary butterflies which correct an off idle response issue on the bike and arent needed in this application, so all the workings were removed. The holes in the TBs were plugged with machined aluminium bungs which were glued in with Loctite retainer.

I have also changed the injectors for Hayabusa ones, not strictly necessary, but they were available and have a bit higher fuel flow rate.

Fuel Pump

This is a bog standard 6 bar Bosch fuel injection pump. They are regularly available on ebay for around a tenner. You will also require a regulator to bring the pressure down to around 3bar (45psi) for most injectors.

Fuel Supply and Swirl Pot

This is needed to ensure that there is no air in the fuel supply to the injectors. Unlike carbs which have a float chamber, and therefore a fuel reserve incase there is air in the incoming fuel, injectors only have what fuel is available in the fuel rail. The swirl pot is fed by the original low pressure fuel pump at the back of the car. A return line also had to be fitted (a pain, meaning half the car needed to be dismantled) to return unused fuel, and air, back to the fuel tank. The swirl pot outlet is then connected to the high pressure pump, which then links to the fuel rail. The return for the rail passes through the pressure regulator and then back to the swirl pot. All of this means there are a lot of fuel lines, and a lot of joints with the potential to leak! The sirl pot can be seen behind the header tank in the pic above.

Temperature Sensors

I spent some time tracking down the correct OE sensors to work with the standard megasquirt settings and finally found them (they are available from Extra EFI too). If you are using natural aspiration, then you can simply use a water temp sensor for both air and coolant temp sensing. The details are shown below. They are about £25 each.

For the following cars:-
Astra G Mk4 (98-04)
Y17DT
Corsa C (02-07)
Y17DT, Y17DTL
Frontera B (98-04)
3.2 Petrol
Meriva
Y17DT
Monterey
3.5 & 3.0TD
Signum
Z30DT
Vectra C (02-08)
Z30DT

 

Tuning

This is relatively easy for my application as I am only using the ECU to control the fuelling, leaving my electronic dizzy control the spark as before. This makes it a lot easier as I already know my spark table is correct throughout the rev range. Meaning if it doesnt run right there is only fuelling to blame!

My best advice is to carefully read through the instructions for the megasquirt system (only rwad the bits that apply to your install otherwise you'll get confused!) and follow the basic guidelines. I did this and mine started first time with no hassle at all. It was very rich, but it was a good start. My base map can be found here for use at your own risk! It is a fuel only, alpha-n map. But can easily be changed to a speed density and adding spark info is straight forward.

For tuning the engine beyond idle, then I use Megalog Viewer, which is a free download. It allows you to analyse datalogs from megatune and suggests areas of the map which need changing and gives values too. It gets you a very good map very quickly indeed.