240 General: High Idle Only In N & P

[john.wigley]

If our 2.3 7 series cars were representative of the breed, then I think that you will still notice it, Alan. It was however more noticeable, as I recall, on carburettor than injection fed cars, to the point of almost stalling on a cold winter's morn immediately after starting, without judicious juggling of the choke and left-foot braking!

Regards, John.

[TheHungriestBadger]

Can confirm the above. My mate with a B230E 740 experiences a rise of approximately 100rpm when going from D to N.

With regards to the modification mentioned earlier in this thread, I too lack any specialist knowledge on the subject but at the end of the day: electricity is electricity (and the same with air, vacuum, fuel, etc.) - just because it wasn't designed for the job doesn't mean it can't be used, provided the design specifications (i.e. voltage, pressure, etc.) aren't exceeded. I too back the notion that it would be a cool experiment

[Othen]

Originally Posted by john.wigley

If our 2.3 7 series cars were representative of the breed, then I think that you will still notice it, Alan. It was however more noticeable, as I recall, on carburettor than injection fed cars, to the point of almost stalling on a cold winter's morn immediately after starting, without judicious juggling of the choke and left-foot braking!

Regards, John.

What I enjoy about the RB project is that can be a test bed.

I’m embarking on the B230/AW70 venture with just an outline plan that might change a bit as the story unfolds. Even with the B230 motor the RB won’t have an ECU as such (just an igniter module, the rest is all going to be done with bits of cable, pneumatic tubes and the odd rod and lever), so there will be nothing to modulate the engine speed automatically when drag increases in D/R/2/1. If transmission drag remains a problem after fitting the B230/AW70 then the reversed anti-dieseling solenoid may well work :-).

Alan

[Othen]

Originally Posted by TheHungriestBadger

Can confirm the above. My mate with a B230E 740 experiences a rise of approximately 100rpm when going from D to N.

With regards to the modification mentioned earlier in this thread, I too lack any specialist knowledge on the subject but at the end of the day: electricity is electricity (and the same with air, vacuum, fuel, etc.) - just because it wasn't designed for the job doesn't mean it can't be used, provided the design specifications (i.e. voltage, pressure, etc.) aren't exceeded. I too back the notion that it would be a cool experiment

Thank you for that - it is really helpful.

The replacement (for a B21a) motor is actually a B230e, but I’m planning to convert it to a B230a using the manifold and Pierburg carburettor from the RB. The carburettor will be much simpler than K-Jetronic (the aim being to extend the RB’s life by a decade or so rather than enhance performance).

I need to do a bit of thinking about a control system because I don’t think the starter immobiliser idea will work (as I explained above). I think the anti-dieseling solenoid idea might be sound.

:-)

[Bob 1967]

Mine has the BW55 /b21a combo .
In P and N the revs will rise due to lack of drag.
When engaging R ( backing out of the driveway) the revs drop ,if its cold it can stall.
I imagine in a manual pushing on the clutch would also increase the revs.
As an ex biker I can testify that this is most certainly true on any of the bikes I have owned.

[TheHungriestBadger]

Good to know Bob, thanks for adding to the pool o' knowledge. I still maintain that the rev increase thing probably shouldn't be a 'feature' of the LH2.4 system. Again my reference being the OBD diagnostics 'wiki' page which states:

Engine idle speed compensation for automatic tran OK 1-2-4 (depress the brake pedal, move the selector to D and then to N.)

This is certainly a function built into, and 'functional' on, (at the very least) my specific vehicle; I have run this specific diagnostic test already and received the 1-2-4 code.

Although perhaps it is referring to RPM compensation when in gear (i.e. avoiding the near-stalling issue as mentioned by those running carb'd vehicles)? On the off-chance that anyone can clarify the above, or if anyone wishes to add their own speculation to this last point, please do. As per, thanks all once again 🙂