Installation manual
7-9
90-898305
Loose Fuse Holder
2.5 & 3.0 LITRE
If the DDT shows a fault on all 6 direct injectors, fuel injectors, or ignition coils,
it is not likely that all 6 of these component have failed, make sure the fuse for
that circuit is good and that it is making good contact with the fuse
socket/connector.
2.5 & 3.0 LITRE
An engine that surges between 1200 and 2000 RPM may have a missing
tracker valve spring. The fuel and air pressure may not indicate any problem
and normally the engine will run good below and above this RPM range.
Fuel Injector Test
2.5 (1998 MODEL)
When doing the fuel injector load test, with the DDT, the sound from the # 4 &
6 fuel injectors may not be as loud or as many pulses as the other injectors.
This is normal and should not be considered a problem or fault in the engines
electrical system. The 1999 ECM software has corrected this condition.
Fuel Pressure (Pressure No Volume)
2.5 & 3.0 LITRE
There have been reports of a loss of top RPM. No warning lights or horns are
indicated. The engine has symptoms that strongly indicate loss of fuel. Runs
up to full RPM for a short time (seconds) and then drops down in RPM, or may
not get to full RPM at all. The pressure gauge may indicate good fuel & air
pressure 90 & 80 psi. To confirm that the fuel supply is adequate,
restrict/pinch off the fuel return hose between the fuel cooler and the VST.
This test should be performed at WOT. When restricted the fuel pressure
should rise quickly to above 110 psi. If not, there is some type of fuel supply
problem.
Weak Spark (Ignition Coil)
2.5 & 3.0 LITRE
The ignition coil used on the Optimax product has a magnet inside. If the
magnet is installed up side down, the engine may run rough or misfire. The
ohm value will be correct and the DDT will likely not detect a fault. Usually the
problem can be detected by performing the cylinder drop test with the DDT at
the RPM that the engine is running rough or misfiring. Then switch the coil to a
different cylinder and test again. NOTE: The faulty ignition coil may also be
hot to the touch.
Notes
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