PeachParts Mercedes-Benz Forum - View Single Post - OM603 - Why does ALDA adjustment affect shifting so much?

LUVMBDiesels · #3 02-24-2010, 05:19 PM

Quote:

Originally Posted by punkinfair

the shutoff valve on my '87TD went bad and i replaced it. the ALDA came off in the process so i adjusted it 1.5 turns CCW. off the line acceleration was greatly improved and shifting was smoother too. the only issue was mileage went down drastically. i removed the ALDA again yesterday and set it back to the original spot. now i can't stand the way the car shifts, it is hard into second and worse into third. the car needs the diff carrier mounts replaced also, and this makes for a nice 'clunk' into third gear, depending on the throttle position when it shifts the 'clunk' is more or less pronounced.

so what exactly is going on? if the ALDA is controlling mixture, why does the richer mixture so drastically affect the shifting of the transmission? also, is it normal for mileage to take a nosedive when the ALDA is adjusted 1.5 turns CCW?

There is a vacuum hose going to the ALDA as well as a boost signal hose. The vacuum hose is supposed to limit fuel enrichment until the car warms up by bleeding off the boost signal. I bet the hose or the 'Y' connector is cracked. I just removed my ALDA and my mpg stayed the same. You just have to get used to not sticking your foot past the floorboards like you used to have to do...