FIAT 124 Spider
Engine Maintenance + Modification
48
Component Description
ECU
P/N CU97X
The ECU is a small computer located under the glove box. It is not a serviceable
component. The connector on the ECU is used to test many of the sensors in the
FI system.
5.10 Fuel Injection Tuning
A fuel injected Spider does not require (or allow) mixture adjustment. Tune-ups typically
include the steps outlined above (in “All Engines”), setting the idle speed, and adjusting
the throttle position switch. The oxygen sensor should also be replaced if it is old or
questionable.
5.10.1 Replacing the Oxygen Sensor
How old is your oxygen sensor? Don't know? Replace it. Sensors are good for
approximately 30,000 miles. However, if your engine is running very poorly then do not
replace the unit until good performance has been restored. No matter what you’ve read
or heard the oxygen sensor on your Spider is not going to cause the vehicle to run
poorly. Most people are not aware when the O2 sensor fails because the changes in
performance are typically minor. Certainly the engine runs better if all sensors are
working properly, but the O2 sensor will not cause your car to go from running great to
hardly running. If you’re having performance issues that are major look elsewhere and
leave your old O2 sensor installed so you don’t ruin a new one (they damage very easily
with overly rich or lean engines).
5.10.2 Idle Speed Setting.
Run the engine to normal operating temperature. On cars with automatic transmissions,
set the parking brake, block the wheels, and put the transmission in "D". Completely
seat the idle speed screw. Loosen the accelerator linkage stop screw retaining nut and
adjust the stop screw to achieve 800 to 900 RPM on manual transmissions and 700 to
800 RPM on automatic transmissions.
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