Ferrari Mailing List: Re: FI temperature sensor on the 328 ?

[Rick Lindsay (rolindsay]

Rui, Jeff, et al.,
   One thing hit me resulting from a private
conversation with Rui; The Bosch connectors on his car
are not original.  There is a chance - just a chance -
that the connector on the thermotime switch is wired
incorrectly, putting voltage on the injector all the
time.  A quick check with a meter will verify.

regards,

rick

--- Jeff Greenfield <coyote [at] acme-ltd.com> wrote:

> Rui - 
> 
> Several things to check  ...
> 
> First of all, there is always pressure behind the
> cold start injector. In
> order to verify that the injector is not leaking,
> you need to remove it from
> the plenum, and energize the fuel pump (pull off the
> connector on the side
> of the air flow meter with the key on and the fuel
> pump should run). When
> this is done, it should be dry with no signs of
> seepage.
> 
> That done, you need to verify that that the wiring
> to the cold start
> injector is ok, and that it is not energized when it
> shouldn't be. AFAIK
> there is nothing that controls this other than the
> thermo time switch and
> possibly a relay. 
> 
> I believe that there is a pretty good wiring diagram
> of the fuel injection
> system in the owners manual. This is easier to
> follow than the big one for
> the whole car, but some of the wiring is still
> pretty convoluted.
> 
> There are two other temperature sensors. There is
> one in the bottom of the
> coolant tank. This controls a vacuum switch that is
> somehow related to the
> fast(er) idle when cold. 
> 
> There maybe another in your car, (I know your car is
> euro spec and as such
> does it have an oxygen sensor in the exhaust? If not
> this may not apply to
> your car) ... in the oil circuit, there is a 'T' on
> the bottom front of the
> engine, and there is a temperature sensor there.
> This sensor tells the
> system to go into closed loop operation and start
> using the oxygen sensor to
> regulate the mixture.
> 
> Both the above sensors are open/closed type. I
> forget which way they go, I
> think that the one in the coolant tank is closed
> when cold, open when warm,
> and the other one in the oil circuit is open when
> cold and closed when warm,
> but it is easy enough to determine if they are
> working with an ohmmeter when
> cold and warm.
> 
> Make sure that the throttle switch is working too.
> There are three pins, you
> should have continuity between two when the throttle
> is closed, there should
> be no continuity between any pins when the throttle
> is opened slightly, and
> there should be continuity between one of the same
> pins (when closed) and
> another when wide open.
> 
> If your car does have an oxygen sensor, there should
> be an inline fuse
> underneath the panel under the right side of the
> trunk where some of the
> relays and the FI ECU is located.
> 
> If this fuse is blown, the whole system will not
> work correctly.
> 
> Lastly, again this depends on whether your car has
> an oxygen sensor, but if
> it does you can get the fuel mixture close by
> measuring the duty cycle at
> the frequency valve. They say it should be about 55%
> - 60%, but my car won't
> run well until about 70%.
> 
> I went through most of this on my car a couple of
> years ago when it wasn't
> running well, and found a whole bunch of problems.
> 
> LMK what you find and I'll try to help as best as I
> can.
> 
> Jeff
> 
> 
> -----Original Message-----
> From: Rui Gigante [mailto:rui.gigante [at] gmail.com] 
> Sent: Saturday, June 09, 2007 5:28 PM
> To: Jeff Greenfield
> Cc: The FerrariList
> Subject: [Ferrari] FI temperature sensor on the 328
> ?
> 
> Hi listers,
> 
> after a hard period at work I've found some time
> today to play with and
> drive the 328. Some of you might remember I
> suspected a problem with the
> master brake cylinder, but it didn't happen again
> ... and the test suggested
> by Jeff indicates that the booster is ok. I guess
> the master is just
> starting to let go ...
> 
> So I've turned my attention to other matters, like
> the fuel injection. At
> the beginning of the year I've replaced the thermo
> time switch because I had
> a hard time starting the car when hot, and checked
> fuel pressures at a
> certified Bosch shop. All was ok, and the car starts
> ok when hot, even if it
> sometimes takes a bit longer than when cold.
> 
> When I came back from a very "animated" drive today,
> I've noticed that the
> exhaust smell seemed to indicate a rich mixture.
> I've always been a bit
> suspicious about the fact that when started cold, it
> never gets the rpm past
> the 1,000, like I guess it should. It just idles at
> the same speed, cold or
> warm. So I've decided to disconnect the auxiliary
> injector at the plenum
> (engine warm), and voila, the rpm climbs to 1,400
> rpm !!
> 
> That shouldn't happen, since I've checked that the
> thermo time switch in NOT
> providing a ground path for the injector with the
> engine hot, but didn't
> check if I had 12v at the injector ... So I guess
> one of two things might be
> happening:
> 
> 1- the injector is faulty and is always on, and
> someone in the past has
> "tuned" the idle to compensate
> 2- I think there is a separate temperature sensor
> for the FI. If it's
> faulty, then the electronics "think" the engine is
> always cold, and keeps
> the injector on. I'm assuming in this case that the
> injector is actuated by
> the electronics and not directly connected to the
> thermo time switch. And
> the water temperature sender and gauge work
> perfectly ...
> 
> What do you guys think? Any ideias ? The car starts
> and drives great, but
> I'm sure this is a problem I need to solve.
> 
> Rui
>
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