Hehe, they seem to pop up on Ebay quite regularly; probably quite a few don't get read much before being re-sold. Well worth reading the early general/introductory chapters before diving into the model-specific chapters. Much easier to understand the intricacies if you have a reasonable baseline of general understanding first. Wikipedia also has a useful 'carburetor' page for general background. Good luck fella. If anything doesn't make sense, feel free to PM me for my best efforts at helping.
Got the gunson CO tester on it today, turns out the CO% was around 7-10%. Might of been why it wasn't running correctly
I've set the idle + CO (To 1.4-1.7%, VW says 0.5-1.5%), and it runs perfectly. I set the idle + CO with the headlights, fan and heated rear window on, but when I turn them off the idle goes up to around 1200rpm. I know it is less load on the engine with them off, but shouldn't the idle stay the same? cheers.
I don't think these carbs are quite clever enough to keep the same idle speed irrespective of engine load. Tweak the idle down to where you want it (anywhere between about 750 and 950 should be fine) with minimal/normal electrics turned on. Shouldn't need to adjust the CO again, but may be worth re-checking after a while, once you're happy with your idle speed.
May have to do that, but when I was playing with the electrics yesterday it didn't seem to fluctuate on idle. I'll have to try again, but I think it might keep the idle stable when cold, and then do what I described above when warm...
When it was running waaay rich, the revs/load relationship would have been 'odd' because you were so far from optimal air/fuel ratio. So it may have looked like it was compensating for load changes 'cleverly' when it was actually just running 'less badly' as the load increased and used more of the excess fuel; if you see what I mean! Whatever you do, make sure it's fully up to temp before trying to set idle speed and CO.
@EZ_Pete this topic is very informative especially due to presence of detailed pics. all is clear about the choke mechanism, except for a 'final touch' which in my case means 2 questions: - what happens with the cam stepper when the engine is stopped and gets cold ? to me it looks the fast idle screw will hit the cam and get stuck, thus rendering useless the entire choke for next engine start... - what are the steps for putting back a fully disassembled choke ? in your picture the A, B, C, D parts, small springs and stuff + mounting to carb ipper body. maybe an installation movie uploaded to YouTube ?
I need somebody to clear my understanding and confirm the operation of a Pierburg 2E3 choke system from cold engine to warm and back to cold. I will attach a reference photo below. There are 2 scenarios to debate on: A - IDEAL case (aka "this I would like to happen") Cold engine (-10 deg. C outside) -> The choke flap is closed and the fast idle screw (3) rests on the highest cam of stepper (2). We start the engine without touching the throttle pedal. Engine starts at fast idle (2300 rpm), thermo-time valve (TTV) kicks in heating the bi-metal coil at 12 V and then is shut off while bi-metal coil is now heated by coolant as the engine is warming up. The bi-metal coil forces the choke flap to open gradually and in the same time the stepper cam (2) rotates counter clockwise and screw (3) 'slides' to lower and lower cam thus lowering the rpm to 800. So far we NEVER touched the throttle pedal and waited in neutral for the engine to warm up. Now we go for a short trip, park and stop the engine. Basically all happens in reverse, the bi-metal coil contracts closing the choke flap and forcing the stepper (2) to rotate clockwise and raise the screw (3) to highest cam, ready for a new cold start. B - REAL case (aka 'semi-automatic') Same as above with a couple of major differences: the spring that drives the stepper has no force to overcome the friction between the screw (3) and cams while the engine is warming up, respectively the bi-metal coil has no force to raise the screw to the highest cam while contracting after the engine is stopped. We have to do 2 things: 1) drive after a cold start without waiting for the engine to fully warm up and so by using the throttle pedal, we raise the screw from cam each time allowing the stepper to rotate and the screw to rest next time on a lower cam; 2) before a cold start, we press the throttle pedal 1-2 times fully to allow the stepper to rotate and position the screw on a higher cam. So what do you think ? What is true and what is not ?
