Injector Flow Test: Once you have the wires properly installed it's
time to do some preliminary tests and tuning. The first thing you need to check
is that the fuel pump and the injectors can handle the necessary fuel flow. Make
sure all fuel lines are tight and there are no fuel leaks otherwise a fire and
death may result. Did I cover my butt enough by telling you to get fire
In this step you're going to test all 4 Injectors and the Pump for flow. Do
this in a well ventilated area (preferably outside) that is free of all ignition
sources: Gas heaters, wood stoves, welding and grinding sparks, cigarettes,
electric motors, children with matches, etc. Also it would be a good idea to
grab that spare fire extinguisher and keep it handy.
Injector Hot Wiring: Disconnect the 12 pin
connector from the computer and locate the 4 wires that run to the injectors.
You need to take these 4 injector control wires and wire them through a 12 volt
stop lamp bulb (1157) and then to ground. The bulb serves to limit the current
to the injectors.
To put it a different way, jumper the 4 injector wires together at the
connector, connect them to one wire of a taillight lamp, connect the other wire
of the lamp to ground. The injectors will already be wired to a 12V source so it
If wired properly your ignition switch will light the bulb and all 4
injectors will spray.
Fuel Flow: Remove the injectors from the intake
manifold but leave them connected to the fuel rail. Slide some fuel hose over
the injectors and place the hoses in separate containers so that you can capture
the fuel they will be spraying. Another option is to drill holes into 4
container tops and spray directly into the containers. This allows you to check
the spray pattern as well.
At the fuel pressure regulator, take the return hose to the fuel tank and
mount it so you can see the fuel that is being returned to the tank. Make sure
it is securely mounted so you don't have fuel spraying around the shop.
Fake-out your Pressure Regulator: Now you need a
way to make the fuel pressure regulator think it's seeing turbo boost. Adjust
the air regulator on your compressor to how much max boost you think you will
make. (15 pounds for example). Connect a hose from the boost reference port on
the fuel regulator to the air regulator on your compressor. A cheap air tank
with 15 pounds of pressure in it will work in a pinch.
Hit the Key: Turn on your ignition; the fuel
pump, the taillight, and all 4 injectors should turn on. Fuel should be flowing
into the gas tank and the individual injector containers. If there are any
fuel leaks or fuel vapor spraying in the air, stop and fix the problem NOW. Fuel
vapor is extremely volatile.
Set your fuel pressure to 30 PSI without the air hooked up and make sure your
fuel pressure increases to 45 PSI when the15 PSI fake boost pressure is put on
the regulator reference port. Note how much fuel is being returned to the
tank with and without the extra 15 pounds of pressure. If the return fuel line
goes dry when the air pressure is applied then your pump is too small to
feed the injectors at max boost. If you were to run the car like this it will be
too lean under boost and you will damage the engine. You must correct this by
getting a bigger/better pump, connecting two in parallel, or use the
Boost-A-Pump method (soon).
If the fuel pump tests ok, empty the containers that the injectors were
spraying into and this time get your watch out and run the injectors for exactly
1 minute. Measure the output of each injector. Check the output against what you
expected the output to be and against the other injectors. If the injectors are
different by 4 or 5% then you need to fix that problem. In a port
injection system you want the injector flow rate to match as closely as
possible. Try cleaning the injectors, weed out the ones with the bad spray
pattern, get some more, or fix the problem another way.
If everything is OK put everything back together because your going to be
hearing the purr of the motor soon. Congratulations.