Alda again. On N/A W123 engines.
 

I've acquired two 617.912 engines in the last couple of weeks; one in a 1981 300D California <with EGR>, and one from an unknown year, but non-EGR.

Neither have turbos, of course.

Both have ALDA controllers on the IP. I was under impression, from recent posts, that the ALDA is only used on turbo motors, and tunes the mixture under boost. Clearly, and ALDA is also used on N/A 300Ds.

What does it "tune" in non-turbo motors? Is it a mixture control strictly for emissions? Is there a way to set it with a CO/HC meter?

--frankb

That is the ADA. It is similar to the ALDA. It reduces the amount of fuel available to the engine at pressures lower than 1 atmosphere

. . . that is, up in the mountains. So, it's an altitude sensor. Note that ALDA also is sensitive to altitude as well as the much-discussed boost input from the turbo.

The ADA and ALDA are the same thing but with a different case design.

They both have two sealed copper bellows inside that expand and contract based on pressure.

This makes me think about hooking up a small amount of pressure to it for added boost on the good old 240D :D Then if smoke becomes a problem I could just cut pressure.

EDIT: more thinking confused me, more pressure added would mean lower "atmospheric" pressure it would see, or a "lower" elevation, right? As you go up the mountains you loose air pressure due to the lower air density.. so that explains why hooking up a vacuum line like the PO on my car did KILLS performance.

Feel free to correct me if im wrong.

If you are driving at or near sea level, the ADA will already be maxed out. However, it could be set too lean to begin with, we often see this with ALDA. You certainly could try adjusting it for more fuel and see what happens. Too much fuel and you will smoke and have worse fuel economy.