Fuel Injector Balance Test. Cadillac Concours 1997

For 1990-2009 cars

### Circuit Description

Refer to

#### Fuel Injectors

Engine Controls Components
IAT/ ECT/ TP/ MAP and BBV Sensors
Fuel Pump and Relay
OBD II Symbol Description Notice
ESD Notice
for an electrical diagram of this circuit.

The Fuel Injector Balance Test compares the performance of each of the cylinder by using the PCM to shut off fuel injection. This measures the performance of each cylinder by the amount of RPM drop caused by that cylinder not producing a power stroke. If proper fuel delivery has been determined, then a cylinder that does not show good performance (RPM drop) indicates either an ignition or mechanical problem.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. Idle quality should get worse when an injector is disabled. The engine should miss and the idle will become rough.

#### Power Balance Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check
2 | Has the Fuel System Check been performed? | -- | Go to Step 3 | Go to Fuel System Diagnosis (Fuel System Check)

3

1. Connect the scan tool and select Inj. Balance test.
2. Record change in engine speed and idle quality as each cylinder is disabled.

Were engine speed and idle quality changes for all cylinders equal?

--

Go to EVAP Control System Diagnosis

Go to Electronic Ignition (EI) System Diagnosis (Ignition System Check)