What are these PDFs modifying exactly? (Cruise Control, Shaking under partial load)

[JamesDean]

I cant quite follow whats going on for some reason... It not clear to me what exactly they are doing:


http://www.startekinfo.com/StarTek/outside/12264/Program/Engine/Cruise/30-576.pdf

http://www.startekinfo.com/StarTek/outside/12264/Program/Engine/Cruise/30-577.pdf


In my 300D 2.5 I get this annoying surging/shaking occasionally and I came across these PDFs to make changes to supposedly compensate for that but I've not a clue what its actually changing/compensating. I've used two different repaired amplifiers. They have been testing my 190E and are nice smooth operating units. I swapped out actuators with my 300SD (which was smooth too) and none of it had any effect on the surging/shaking.

I am thinking it might be my speedometer cable. It seems when the needle is nice and solid, cruise is largely OK, but when the needle gets some bounce, the cruise reflects this...

[cullennewsom]

Looks like they're having you install a limit switch to detect foot-feed pressure (deceleration request), and disable the CC servo. Don't have time to study it carefully right now.

[SuperCow]

It bypasses the overload protection. (as in it activates it)
So, it will not use turbo pressure.
Because the tempomat whats to accelerate with 1 meter a sec.
Then the turbo kicks in (there is some turbo lag) and your starting to accelerate faster, and the tempomat releases the throttle.
This becomes a cycle, as surging.

[cullennewsom]

Originally Posted by SuperCow

It bypasses the overload protection. (as in it activates it)
So, it will not use turbo pressure.
Because the tempomat whats to accelerate with 1 meter a sec.
Then the turbo kicks in (there is some turbo lag) and your starting to accelerate faster, and the tempomat releases the throttle.
This becomes a cycle, as surging.

Ahh, lag, oscillation.

[JamesDean]

Originally Posted by SuperCow

It bypasses the overload protection. (as in it activates it)
So, it will not use turbo pressure.
Because the tempomat whats to accelerate with 1 meter a sec.
Then the turbo kicks in (there is some turbo lag) and your starting to accelerate faster, and the tempomat releases the throttle.
This becomes a cycle, as surging.

Interesting.

I believe I am seeing this on my 300D but I am not sure its caused by the turbo or by the bounce in my speedo needle.

Being that I've swapped over to a pressure based actuator and have remove EDS control from the turbo... Would this PDF even be applicable?

[SuperCow]

I said turbo pressure but i meant the overload protect is fuel based.
There is a vacuumvalve thats controlling the fuelpump.
I believe the ALDA is controlling this.

see PDF

[JamesDean]

Originally Posted by SuperCow

I said turbo pressure but i meant the overload protect is fuel based.
There is a vacuumvalve thats controlling the fuelpump.
I believe the ALDA is controlling this.

see PDF

I see fuel based control...

I do have one of those pressure switches on the manifold. I am not sure if it goes to a switchover valve that is connected to the ALDA.

So the modification has the following:
when cruise is engaged, overload switch is open allowing boost pressure to engage alda to limit fuel and thus boost?

[scottmcphee]

There were a couple hacks invented in the field to smooth out hunting cruise control on slight inclines, these made it into later year manuals. I think this is related.

[SuperCow]

In your PDF, the switch S27/7 the open wire goes to the pressure switch.
So with the CC on OFF the relay is connecting the ground.
Putting the CC on ON the relay is activated and breaking the ground connection.