weber efi

[Wilman Lee]

----------
> From: nluker <nluker at one.net.au>
> To: diy_efi at efi332.eng.ohio-state.edu
> Subject: weber efi
> Date: Friday, May 22, 1998 4:45 AM
> 
> hi everyone
> Ill answer the answers to my inquiry in order.
> 
> Is it the Weber Alpha system  which is sold as an after market system to
> fit Weber carb manifolds ?
> 
> 
> 1/ No i dont think this is the after market weber alpha system
> 
> 2/If You need informations regarding the Eprom's program Maybe I can
> help You..
> 
> I had a look at the web page address you sent but it was all in italian
> do you have a address for an english version of this site?
> 
> 3/What do you want to know in particular?
> What model is your car?
> 
> My model is a july 89 maserati 4 door biturbo also known as a " biturbo
> 425i"
> It has a 2.5 litre V6 engine with twin turbo chargers .The car has 2
> ecu's one is based on the weber speed density system which uses the rpm
> and air density to do its calculations the other one is based on the
> marelli microplex control unit
> one ecu looks after the 
> knock sensor
> crank sensor
> camshaft sensor
> wastegates
> twin ignit. coils
> 
> the other ecu looks after the
> six injectors
> fuel pump
> over rev cut
> throttle pot
> water temp sensor
> camshaft sensor
> crankshaft sensor
> air temp sensor
> absolute press sensor
> You'll notice that the cam and crank sensors are shown as going to both
> ecu's
> What I would like to learn is how do the 2 ecu's tie into each other ?if
> they do at all. Are the outputs from the crank & cam sensors sent to one
> then the other or  are the ecu's simply wired in parrallel with the
> sensors outputs

According to my memory, the two ECU are quite separate and use common
sensors to get engine information. One ECU controls the fuelling and the
other
controls the ignition and amal valve (boost).




>  I have seen some circuits to tap into the wastegate signal and into the
> knock detect output  of the earlier boost controllers  to drive a couple
> of leds so you could tell when knock was occuring and then see the
> wastegates trigger. It also showed  when over boost triggered the waste
> gates. The early controller was an analoge device and from what I read
> was also used in early saab turbo's.
> 
>  What I would dearly love would be a pin out of the 2 ecu's so i could
> do this circuit on thelater style ecu,s
> in my car 
> my car will only go to 10 psi boost and then pull back to about 8 to 9
> psi boost. From what every one tells me I should get at least 12 psi
> boost maybe a bit more so if there is a pin on the ecu that goes
> high/low when knock occurs it would make tracing this prob a lot easier
> (i.e. dead knock sensor, noisy valves or to low octaine fuel)

Is your car a manual or automatic? According to our experience, the auto 
car runs a lower max boost. 
Your can try to increase the boost by simply disconnecting the two pin
connector on the amal valve and plumb in a bleed valve between the waste
gate actuators and and the amal valve. Using the bleed valve, you should 
be able to adjust max boost level on the road using third or fourth gear
flat out. If it is an auto, use 2 gear and left foot braking, but not for
more
than 5 secs.


> The manual shows both ecu's with a test connector each. I have found
> these sockets on both ecu's but they contain only one wire each do they
> have to be grounded thru an opto coupler/resistor/LED etc to work? do
> they give out much info? (i.e. can I plug my lap top into them)
>  And finally does any one know anything about downloading the info on
> the eproms in these ecu's and making some sense of it , like were the
> max boost value is.
>  I have noticed that the later 2.8 litre cars have a ego sensor but that
> the 2.5 litre cars dont ( Ive also noticed they are listed as getting
> better M.P.G). Does this mean they run a different ecu? or just use more
> featueres of the same unit?

	All 425s here has carbs rather than injection. Late 430's use a single
ECU to control everything and has a lambda sensor but this system is
actually
worse than the twin ECU system. I believe that there is a fault in the
factory
mapping particularly at idle and low throttle angle.
	Self-diagnostic capability is very poor on earlier models and it is only
limited to fault code reading even if you are using factory diagnostic
equipment.
The latest Ghibli and Quottroporte use twin ECU's again but now one ECU
controls
one bank of cylinders and they are identical and interchangeable.
Diagnostic
on the latter cars are much more clever. You can use a laptop together with
a Maserati tester to read all running values plus checking the ABS, and
Airbag
systems.






>     any help any one can give would be greatly appreaciated
>                 nick luker
>