Fast Idle Pierburg 2E3. DG 1.9 `84

[Worleyboy]

My origional problem has been discussed in a previous topic and I believe/hope now that the problem has been solved by circulating the fuel in the tank through a larger CAV filterfor several hours. The fuel is now beutifully clear.
Having now done a carb cleanout and refitting with rebuild kit things are obviously not quite the same as they were before the carb was removed.
I have had to adjust up the warm tickover maybe 2 turns and she runs a bit fast, back it off to what sounds right and she will stall. So I`ve left it a bit fast for the moment. MOT tomorrow morning. What really bugs me is the sudden increase sinse rebuild of the fast idle revs´, must be well over 2000rpm. They do go down though as the choke warms up. So I realise that I have to adjust ths fast idle and I have read a couple of descriptions of how this is done, but they dont make sense to me. Question, why should the fast idle (choked) tickover be adjusted when the engine is at normal running temperature when the choke flap is open and highest point of the cam is furthest from the adjustment screw and how are you supposed to get the highest point of the cam down to the screw, it just springs back up again? Thanks for previous help chaps, this fast idle adjustment problem has really got me puzzled and "one man spanner" makes it sound so easy

[kevtherev]

The fast idle cam is ultimately controlled by the bi metal spring.
When cold the fast idle can be set by depressing the accelerator once fully before starting (A WBX should start without touching the acc. on start up)
Then when the engine starts a throttle blip should set the fast idle (2000rpm) back down to the next step ( the ambient temperature governs this)

use the three retaining screws on the bimetal spring housing to adjust the cam.
On a cold engine the cam should snap to the fastest idle position with full pedal depression, then it should spring back to ambient temp idle position when the throttle is opened partially.
At 67 deg the fast idle cam should be at it's lowest step

On a cold day a fully choked carb should only take 6-8 mins to open the choke flap fully

[Worleyboy]

Thanks Kev, this sounds like stock info regarding the Pierburg high idle, but what the heck does it mean? My question, Why adjust when the engine is hot, for a cold engine adjustment? And I wonder, should fast idle screw be turned in or out to rais/ lower revs? Maybe can do it by triel and error? Thanks and kind regards for your help.


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[kevtherev]

The throttle stop must rest on the lowest step on the cam, it won't do that if the engine is cold, the spring will not let it.
AS for adjustment the fast idle stop should not be resting on the step when the engine is hot, it should be just off.
That adjustment should be made from the idle speed screw
#1 step = idle speed
#2 = 1100
#3 = 1400
#4 = 2000

[Worleyboy]

Thanks Kev, I will study the info.


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