Engine Maintenance and Modification Bradley Artigue

FIAT 124 Spider
Engine Maintenance + Modification
The Bosch L-Jetronic troubleshooting table is presented in the table above. It does a
good job of presenting many of the common faults with the system and giving possible
causes and remedies. This is followed by troubleshooting problems that are specific to
the FIAT Spider.
Air Flow Meter Failures
According to Bosch, any malfunction of the AFM should result in replacement. At about
$500 each, this isn’t always the best option. Some issues are easy to diagnose and
repair yourself.
A sticking intake valve can cause air from engine compression to push backwards
through the fuel injection system. The net result is often a bent AFM flap and very poor
or no running. Some Spider AFMs have an accommodation for this, a circular springloaded
“door” in the middle of the air flow meter flap that opens with pressure. This
door often blows apart, sparing the flap. A bent flap may be repairable by bending it
back into place or, if the door bent slightly down, by sanding (with very fine sandpaper)
the aluminum surfaces inside the AFM door. A blown circular door can be fixed with
epoxy (it will no longer open, meaning you need to fix the sticking valve or problem that
caused it to blow out).
Keep in mind that if you are stuck on the side of the road due to an AFM door failure, the
circular type should leave the AFM flap workable but with a quarter-sized hole in the
middle. It can be temporarily covered with duct tape as an emergency fix. Attach to the
outside only, you don’t want duct tape sucked into your engine! This procedure works
quite well, as your author learned it the hard way.
Also note, an engine that is bending AFM flaps is going to bend the flap of any AFM you
put on the engine; the problem is in the valve train and should be repaired there before
wasting money on air flow meters.
Temperature Sensor Failure
The temperature sensor is unlike the other sensors in the fuel injection system in that,
when it fails, the car typically will not run. Many times this problem is diagnosed as the
sensor and a replacement occurs. This sensor is in a very hot part of the engine,
exposing the sensor and wiring to harsh conditions. It is important to inspect the wiring
leading to this sensor and make sure it is in very good condition. A replacement
connector and wiring is available to splice it if there is any question.
Click-Click-Clicking Double Relay and Fuel Pump Eccentricity
Assume you are driving along and, while at or near idle, you hear a very rapid click-clickclick-click
(etc!) coming from the passenger side of the car. The double-relay is likely
turning on and off very quickly. This is the result of the fuel pump switch in the air flow
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