Been discussing this one over in Hot-Rods; a couple of regulars have offered their assistance, but the problem isn't quite solved yet.

M119 V8, running perfectly, had the throttle actuator removed to inspect the integral wiring harness. Harness wires appeared to be in A-1 condition on inspection. Internals of TBA also in A-1 condition, no heat damage visible.

Replaced TBA-to-intake gasket and re-installed TBA. Left engine to sit for several minutes with ignition key turned and cluster lights lit, to allow computer to re-learn throttle stop location.

Engine starts instantly, but ASR light remains illuminated, and on test drive, limp-home mode is evident.

Checked diagnostic LED panel. A code 6 (idle speed control inop) is recorded. No other codes. Manually cleared code with the panel button.

Repeated startup procedure; identical symptoms presented (ASR illuminated, limp-home mode active, code 6 stored again).

Another member checked service order notes for his TBA re-install by a dealership tech. It said, quote, "... reset the Throttle Stop, Valves are OK. Cleared Faults. Runs to factory spec."

Two hypotheses here:

(a) the TBA is damaged despite looking good; should be replaced.

(b) the TBA is OK, but my re-install steps are flawed.

Assuming (b) for now. Which leads to three questions.

Is anything required to reset the throttle stop other than just to leave the key in the "on" position for a few minutes? Or does something get manually adjusted?

Is clearing codes from the diagnostic panel button OK, or am I going to have to perform a more specific procedure to reset the persistent ASR fault?

And what might the "valves" be in the service order notes? Only valve I know of in that area is the butterfly valve in the TBA itself, which is fine.

Grateful for any light anyone can shed; I'll write up this whole job as an article once it's finally finished...

s/b

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I've seen these relearn themselves before, but not always. Leave the key on a bit longer, you can lean over the fender and listen, you may hear the throttle motor kind of whining as it runs the flap through it's closed and open range, sometimes takes a few minutes to do it.
IF after several minutes it hasn't done it itself, I'd take it to the dealer or good MB shop and have them do the learning procedure.
Sorry I can't be more specific about which ones seem to do this automatically and which don't, I've had different experiences with these 119 motors like that.

Gilly

Thanks, Gilly! Your experience is invaluable as always.

I'll repeat the key-on learning trick, and I'll listen for sounds of activity this time. Did not note any previously.

s/b

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