Recently acquired 1989 740/B230E rough starting

[Mike F]

No pedal depression pre-start wont make any difference to what the ECU does.
All it reads is pedal position, coolant / air temperatures, rpm and then
reads a suitable injector duration from its look up tables.

On one or two earlier fuel injected Toyota's and Nissans there was a
wax-stat for additonal fast idle enhancement which did require pedal
movement to set them, but was not connected to the ecu and fuelling amounts
in any way.

Tim..

And in this particular case, the big reason that there would be no
difference to what the ECU does is there isn't one. B230E would be
strictly mechanical injection, no electronics at all.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

[Tim..]

And in this particular case, the big reason that there would be no
difference to what the ECU does is there isn't one. B230E would be
strictly mechanical injection, no electronics at all.

The K jet on this application still doesnt have any additional linkage
operated fast idle though, this operation is provided by the aux air valve
which would be fully open when cold.

The richer mixture is provided by the warm up regulator jointly operated by
electrical heat and being bolted to the engine block, which raises the
control pressure of the whole shooting match. N'est pas?

Tim..

 

[Peter K L Milnes]

However there is still a start injector which could stick open (or closed)
giving start problems. The fuel pump relay is also different to that on LH,
Rex/Regina and Motronic systems which are found on 740s and 940s.

All the best, Peter.

 

[Mike F]

The K jet on this application still doesnt have any additional linkage
operated fast idle though, this operation is provided by the aux air valve
which would be fully open when cold.

Right. So any improvement by flooring and releasing the accelerator
pedal could be explained by a dirty throttle body and not much else
except coincidence.

The richer mixture is provided by the warm up regulator jointly operated by
electrical heat and being bolted to the engine block, which raises the
control pressure of the whole shooting match. N'est pas?

Tim..

The control pressure is lower when the engine is cold, and acts on the
top of the control piston, which allows the control piston in the fuel
distributor to rise further for a given force. The force is applied to
the control piston by a lever attached to the plate in the air flow.
The control piston's rise opens up the fuel passages to the injectors -
a higher rise provides higher fuel flow. Very simple in concept, but
sure requires accurate machining!

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)