D-Jet 'progression problems'

[raygreenwood]

Yep...that is usually from very fine traces of worn away brass or copper....corroding across the contacts and held in place by oil film. Ray

[rayray1]

The D-jet "TPS" is more of a motion sensor than a TPS... works along the lines of an accelerator pump.
Motion is sensed by the on/off changes across the contacts, the more motion, the more fuel.

I have a 72 411 doing this bucking thing you describe to a ' t ' . Replacing my tvs ? is a straight ahead plug and play>>? I'm not nearly as versed on all this techi stuff. Although, i have the books, Ray indicates the books are not accurate... so-?

[Rhodrich]

I hate to say it, but I swapped out the complete throttle body and switch with one I picked up in a swapmeet, and the problem was solved. No magic solution I'm afraid!

[Piledriver]

Yep...that is usually from very fine traces of worn away brass or copper....corroding across the contacts and held in place by oil film. Ray

Would it be pratical to make an optical version of that circuit with printed lines (using retroflective paint or such?) I was thinking Hall effect, but that would be much harder to make something compatible w/o some complex circuit.

[rayray1]

I'm glad to report that after soaking the trottle body down with brake cleaner and letting it run thru tvs switch underneath while opening and closing gate, the 411; is now NOT bucking,jerking and stumbling anymore.
What a surprise to lose that behavior after nearly 2 years of seeking and accepting this erratic problem.
thanks for all the advice and direction-
if it returns- down the road again sometime, i'll grab a can of brake clean and wash those contacters out.
I'm just elated to be able to drink a cup of coffee and not have it throw itself onto the windshield and my shirt !

rayray1.

[raygreenwood]

Stoooooooop! Running brake cleaner anywhere into the engine creates an exhaust byproduct that is absolutely deadly. Also....that stuff will kill the TVS eventually. Its very hard on the plastic inside and circuit board varnishes.
You reallly need to get an o-ring and take the TB off properly to do this. It also takes the lube away from the throttle shaft causing faster wear. Ray