Good reference for the 4CU system (Flapper)

[earlybay]

came across this - not TVR-specific but a good reference with ECU internal circuit diagrams ...

http://www.team.net/TR8/tr8cca/wedgelab/injection/...

[Wedg1e]

Aye, it's been around for years... some of the info on the ECU internals is just guesswork though.

[earlybay]

Wedg1e said:

Aye, it's been around for years... some of the info on the ECU internals is just guesswork though.

Ah ok, I'm still very much at the learning stage so every little bit helps ....

Interesting what you say about the internals - so I guess no-one has access to any official Lucas documentation ?

[Wedg1e]

earlybay said:

Ah ok, I'm still very much at the learning stage so every little bit helps ....

Interesting what you say about the internals - so I guess no-one has access to any official Lucas documentation ?

Let's just say that the only people who know will only tell you anything if you can tell them something they don't already know
It's not necessary to know the intimate details of the ECU internals from an electronics repair point of view as they all tend to develop the same faults that are generally easy to diagnose and repair.
Where it gets a bit trickier is in fine-tuning the ECU to match a given airflow meter and state of engine tune - there isn't a fuelling 'map' as on modern systems that can be adjusted. What you have is a set of fixed close-tolerance resistors that can be substituted to modify the response of parts of the circuit: the information on which resistor contributes what and when to the overall picture is the interesting bit. We are talking 2% tolerance resistors here which suggests that a small change in value might effect a large change in the fuelling and those of us who've experimented over the years have yet to publish any definitive answers!
Every once in a while some electronics enthusiast chips in and promises that in no time flat they'll have answers but it hasn't happened yet; what usually happens is the words 'carburettors' and 'Megasquirt' get bandied about...