questions...

[Brian Neill Tiedemann]

Hello all,
I introduced myself a while back, but have been silent. My project is 
beginning in ernest now, and I have a few questions:

We have not decided upon the method of gauging air inflow to the engine.
What are some pros and cons of Air Flow Meter based systems as compared 
to TPS/Manifold Vacuum based systems? What major strengths or weaknesses 
exist in these methods, and is there a consensus as to the "best" system?
Any other systems? What specific sensors are required to implement each?

In discussing common "fuel" circuit configurations, the question of why a 
mechanical type of fuel pressure regulator is commonly used, balanced 
against manifold pressure- does anyone use a pressure transducer in the 
fuel rail and compensate the injector open time for variations, rather 
than using a constant pressure? Any reasons why this is not used?
I wondered about the effectiveness of the injectors over a broad pressure 
range- do they perform consistently with pressure changes? Also some 
method of circulating the fuel around the system for cooling is desirable 
to prevent vapour locks- any other good reasons for circulating the fuel?
What does a fuel temp sensor's input effect directly and why? Is this 
considered only for the charge cooling effect or other reasons?

My project is basically to be a processor based digital sequential 
injection and ignition controller, adaptable to other configurations, but 
to be developed around a cleaned up Rover 3.5 Litre V8 injection manifold 
(actually to be a 5 litre engine). This is a 3rd/4th year computer 
systems engineering project, as well as my special interest. The system 
is hoped to be able to handle LPG ignition control when using an LPG 
carby, with full injection and ignition control available when running 
high octane unleaded fuel. Starting on petrol and switching automatically 
to LPG will be also included. The system is hoped to be able to be 
expanded to handle knock sensing (hence sequential digital approach for 
inj and ign). System will probably be closed loop, and contain at least a 
"power" and "economy" mode for LPG and Petrol operation. 

We (there are three of us working on this) are at present trying to come 
up with a detailed definition for the system/project, and any input as 
relates to current state of the art systems and good/bad points of 
current or past methods would be greatly appreciated. 

At this point I think that timing of injection and ignition will probably 
be derived from crank position directly, and "which cylinder" resolution 
from cam or old distributor drive position (distributor no longer to be 
used). In order to fire the first cyl to reach TDC, cylinder pairs will 
probably be batch fired for at least the initial revolution during 
cranking, then sequential individual events once correct referencing is 
achieved.
Whole system will "talk" via removable data link to a PC for calibration, 
monitoring and data collection (self calibration on the road maybe?).
Anyone with any input relating to aspects of this project, or general 
comments, I would love to hear from you- either here on the list, or via 
direct email if more appropriate to s914440 at minyos.xx.rmit.edu.au

BTW what is the spec and current state of the efi332 project I hear 
mentioned? Can I be subscribed to its proceedings?
I am also interested in what other peoples' projects entail- what 
features do you all hold dear?

That's probably more than too many questions for now anyway, (I will 
probably find many more), so I'll say goodbye.

Regards,
Brian Tiedemann.