Electrical: Throttle microswitch adjustment

[CaptainAhab]

Does anyone know the correct procedure for setting this or is it just 'fiddle until the thing runs right'?

[Clifford Pope]

Is this the Throttle Position Sensor on a LH2.4 electronic system, or a switch on a carburettor?
A description or picture would help.

[Clan]

Originally Posted by CaptainAhab

Does anyone know the correct procedure for setting this or is it just 'fiddle until the thing runs right'?

Why do you want to adjust it ? Once set it doesn't need further adjusting . Try cleaning the throttle flap and inside the housing around the throttle first if the idle is slow .

[Clifford Pope]

I'm only familiar with the TPS on the LH2.4 system, which is why I asked.

It certainly can need adjusting, very rarely, presumably because components wear and a tiny amount of slack develops on cams, switches, rods etc over time.

For years I have noticed on several cars that with electronic systems there is a minute but perceptible "dead" spot when the throttle is closed, on over-run, and then gently opening the throttle again. I have always put this down to the fact that electronic injection cuts off all the fuel on over-run, unlike a carburettor, which wastefully dribbles a bit but which smooths over the interchange from off/on.
Then a few weeks ago I thought about the TPS, and tested the movement for the opening "click", which is supposed to happen the instant you cause the throttle to move. This is the switch that switches the fuel back on again.
Sure enough, I found, or imagined, that the imperceptible interval was possibly a tiny bit longer than "instantaneous".
I followed the procedure in the manual, and re-set the switch position, reducing the free movement to as near as nothing.

The result is an impressive improvement. The tiny hesitation has vanished, and the changeover from over-run to drive is now imperceptible.
So thoroughly do-able, and worth doing.

But is this the set up on your car, or is it something else? Your signature says B230K, which is the Cisac carburettor with semi-electronic Bendix Rex system of awful memory, but I can't recall an electric throttle switch.

[CaptainAhab]

Thanks for the replies guys.

I am on a carb setup, but have recently changed from the Cisac to a Weber 32/34 DMTL.

Following the swap, I noticed that there was a marked difference in the transition from idle to main jet with the switch in the it's original location. I moved it forward slightly so the throttle was more open when the switch closed and noticed a smoother transition. I read somewhere that the Bendix brain alters the timing at idle to try and make it smoother, so it would affect the running of the car if it was held on too long.

It may just be a function of the non-standard carb and I need to fiddle around a bit, but I thought I would ask you guys as there is usually, as now, a useful nugget of info forthcoming.

Cheers,

Rob