Ferrari Mailing List: Re: Check Engine Light - 512TR

[Doug and Terri Anderson (dnt]

Hello Larry -
Good observation on your part - they sure could have.  But what part of the 
engine did./does it affect - saying that "it" is truly loose.  Many Ferrari 
engines are simply either 2 four cylinder engines or 2 six cylinder engines 
hooked together by a common crankshaft in a common crank case.  In other 
words - they can happily run on half a motor - spewing raw gas down the 
pipe.  I have such a goblin now in my '78 308 GTS.  1978 Marrelli 
distributor - oh my.  What a Rub Goldberg device.

SO - first off - what does your owners manual say those lights are for?  I 
do not think this a true Check Engine Light - and when these are commanded 
on they, by themselves, may not set a code.  But then what?

OK - here's a guess, only cause I don't know what year your car is, don't 
have one, and don't have a shop manual - BUT that said - I do know emission 
devices - and I believe this is not a CEL issue.  Wha?  Yeah.  What those 
7-12 lights are a rudimentary engine miss warning system.  How's that?

Well, lets flash forward to 1996 and OBD II - an engine miss - the only 
engine problem that will command the true check engine light (usually a 
silhouette of an motor block) to blink.  The monitor can count engine 
misfires and packages them in bundles of 200 misfires by measuring the crank 
slow down amplitude between spark plug firings - now THAT is a monitor - two 
or three consecutive packages of 200 misfires commands the PCM to illuminate 
the MIL - malfunction indicator light - takes the place of check engine 
light & the two little "Slow Down" lights.

So, when a full charge of unburned air/fuel mixture fails to ignite in the 
combustion chamber and travels down the pipe and lights off in the exhaust 
system or the cat - it can melt the cats substrate.  Ayep - just as 
assuredly as if the catalytic converter substrate were made of a wax honey 
comb.  AND that is why it is the MOST important monitor on an OBD II system.

Anyhow, back to your system - so failing to have an OBD II misfire monitor, 
it uses a heat sensor thermocouple.  Defined as "A thermoelectric device 
used to measure temperatures accurately. . ."  and these things are hooked 
up to one of two lights - 1-6 or 7-12 if there is a spike in a dangerous 
temperature.

That said - - - look for a spark plug(s) misfire.  I am not sure there is a 
reset on these - excessive temps - on goes the light.  So I am interested in 
what happens in the morning after a good cold soak restart.

Woof - that's too much babble.  But you do drive a great car and I wanted to 
this to you.  Who knows, you may be in my neighborhood some day and offer a 
chance to drive a TR.  heh heh

Keep us posted, Larry - onward

DOUG