Bosch Spider Starting (L-Jetronic)

[Bill Bain <BBain@xxxxxxxxx>]

There's been some discussion of hard-starting Spiders here, but mostly
about SPICA ones.  There was a question about a mid-80s Spider.  The
Bosch L-J EFI system is pretty simple, so let's start at the top.  There
is a detailed flow-chart for diagnosis in the shop manual, and the AROO
Web site has something similar, so there's no need for guesswork.  The
CarDisc CD is worth every penny, and a DVM (digital Voltmeter) can be as
cheap as $20 from Radio Shack (U.S. consumer electronics store for our
friends across either pond).  Here's some additional thoughts:

1.	Since the car starts right up when it's warm, it's not likely
that there's a mechanical problem (like timing).  Start with the
electrical system.  CLEAN THE FUSES FIRST.  Rule 1.5 of happy Alfa
ownership is that a clean fusebox means a happy car.  Rule 1.0 is that
ya gotta love 'em! :-)

2.	The L-Jetronic system will not allow the plugs to fire if the
ECU doesn't "see" at least 10.5 volts.  Thus, it's a logical place to
start.  If the Spider starts when you release the key from the "start"
position to the "on" position, it could well be that the engine is still
spinning when the key is released, but since the starter motor is not
engaged, the drain on the battery is less and the ECU "sees" more than
10.5 volts in that 1/8 of a second and the plugs fire.  Have a friend
crank the starter while you measure the voltage at the battery terminal
posts (not the cable connectors -- you want to read what the battery
"sees")  with your DVM.  Check your battery connections -- sometimes
there's enough corrosion between the clamps and the terminal posts to
cause all sorts of gremlins.  You should clean the battery clamps and
terminals, and the negative cable should also be cleaned where it
attachs to the body in the trunk.  If the voltage is still low, charge
up the battery.  Once you get the car running, check the voltage at the
terminals. If it's less than 13.5 volts or more than 14.1 (from memory -
get the values from the shop manual)  the voltage regulator may need
attention.  Running the car may charge the battery well enough that the
problem doesn't show up on a warm engine.  Sometimes, particularly with
modern batteries, the failure mode for batteries is relatively sudden
and the real fix is to replace the battery.  If you don't have
consistent voltage, it'll be pretty difficult to go any further.

3.	OK, you've got voltage.  Hard cold starting could also be a
problem with the cold start injector.  Clean the contacts.  The shop
manual has the procedure for checking it and for checking that the
injector is actually spraying fuel into the plenum -- it involves
removing the injector while it's hooked up and having it spray into a
container.  I've never had to go that far.    Check that the thermo-time
switch is working since it opens the cold start injector for a
pre-determined amount of time based on engine temp.  Also check the
coolant temperature sensor -- if the ECU thinks the car is warm when
it's not . . . .  The test values are all in the manual, and to this
point the diagnosis has all been "non-destructive" so you can easily
check all this in a couple of hours without having to tear anything
down.

If all that checks out OK, then it might be time to delve deeper into
the charts and look for more esoteric failures.  We'll expect a full
report on Monday!  :-)

Bill Bain
President - AROC Atlanta
'83 Spider (been there, done that).

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End of alfa-digest V7 #65
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