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3. Bring the vehicle to a complete stop and set the parking break. Increase or decrease the amount of fuel delivered during high
engine speeds by turning the HIGH RPM adjustment knob either clockwise or counter-clockwise. If your vehicle is equipped with a
Rich / Lean indicator, adjust the HIGH RPM adjustment knob until the meter indicates a stoichiometric fuel mixture at high engine
speeds.
4. Adjust the HIGH RPM adjustment knob accordingly and continue performing acceleration tests until you achieve a quick, crisp
response during acceleration.
TUNING THE CHOKE
The CHOKE adjustment knob controls the fuel delivery to the engine during a cold start. The CHOKE adjustment knob
DOES NOT
control the “ON” time for the fast idle solenoid. Adjustment to the CHOKE should be made after the engine has cooled down
completely.
1. After the engine has cooled down completely (Holley recommends allowing the engine to sit overnight), start the engine.
2. Immediately after starting the engine, shift the transmission into gear and accelerate slowly.
3. Turn the CHOKE adjustment knob to achieve a clean drive-away from a cold start. Several cold starts will be necessary to zero in
on the proper CHOKE setting.
CLOSED LOOP INSTALLATION AND CONNECTION (OPTIONAL)
DANGER! NEVER WORK UNDER A VEHICLE SUPPORTED ONLY BY A JACK. ALWAYS SUPPORT THE VEHICLE WITH JACK
STANDS THAT ARE IN GOOD OPERATING CONDITION. FAILURE TO DO SO MAY RESULT IN PROPERTY
DAMAGE, SERIOUS INJURY, AND/OR DEATH.
WARNING! If you are currently using a Holley analog closed loop kit, P/N 534-27, all electrical wiring connecting to this kit
must be removed and replaced with a new wiring harness, Holley P/N 534-56. Failure to replace this wiring
harness will result in improper fuel delivery and possible damage to ECU.
WARNING! Use only unleaded fuels when operating an oxygen sensor. Use of Leaded fuels will DESTROY the oxygen
sensor and will result in incorrect exhaust gas oxygen readings.
WARNING! The use of some RTV Silicone sealant will destroy the oxygen sensor. Ensure that the RTV silicone sealant that
you use is compatible with oxygen sensor vehicles. To determine compatibility, check the packaging of your
RTV silicone or contact the sealant’s manufacturer.
NOTE:
Federal Law prohibits the disconnection of AIR pumps. The use of an oxygen sensor in conjunction with an AIR pump may
result in an extremely rich fuel mixture, resulting in possible damage to your engine.
NOTE:
The installation of an oxygen sensor will operate with the digital ECU. This requires use of the Holley Digital
PRO-JECTION
2D
Closed Loop Kit for 1 and 2-Barrel Applications, P/N 534-54.
The digital ECU is designed to utilize a heated, three-wire oxygen sensor to operate the system in a closed loop mode. When operating
in a closed loop mode, the electronic control ECU utilizes a reference signal from the oxygen sensor to determine whether the engine is
running too rich or too lean. The ECU then adjusts the fuel delivery to maintain a stoichiometric fuel delivery (14.7:1 Air / Fuel Ratio).
1. Disconnect the
PRO-JECTION
2D
wiring harness from the rear of the ECU by depressing the small latch on top of the harness
connector and gently pulling the connector out of its socket on the ECU.
2. Determine a location in the exhaust system in which to mount the oxygen sensor. This location must be as close to the engine as
possible. Good mounting locations are in a header collector, the drop pipe, or the “Y” pipe on a single exhaust system.
WARNING! The oxygen sensor must be mounted in a location that will prevent the sensor from being damaged by road
hazards or moving parts on your vehicle. Failure to do so will cause damage to the oxygen sensor, resulting in
substandard system performance.
NOTE:
If your vehicle is equipped with catalytic converters, the oxygen sensor MUST be located between the engine and the catalytic
converters.
