Second what Pete said, only caveat to add is that the plunger will (if ttv working) retract fully on ignition thus allowing the cold start procedure to engage. From that point it's really all about coolant temp. Waxstat takes over, or in my case doesn't properly because it's faulty and there is no one on planet earth selling one then coolant heats to temp and plunger goes into its midway position (which is basically your idle). Easy way to check is to whack the air filter off and just watch the start up procedure via the plunger. So, Off: fully extended+touching grub screw Ignition: plunger retracts fully After a few seconds (temp depending): plunger goes to a midway position resting on grub screw. If that's not happening then you've at the very least got an issue with the TTV. That could mean a leaky diaphragm, blocked vacuum port (bottom hole can easily get blocked with dirt). The TTV should make an audible click when you turn on the ignition. The illustrations posted above go through the entire start sequence, really useful to see how it works in respect to diagnosis. But first things, definitely check the earth strap from the carb to the valve cover bolt, always worth whack a new one on!
Also forgot to add. Check the temp of the auto-choke housing and waxstat housing on ignition. These should both get really hot to touch in a very short period of time. I'm just thinking you did a coolant change and perhaps the manifold o-ring finally have up the ghost. If that's happened then the coolant won't get enough flow/hot enough to allow all the pierburg components to properly initiate the cold start sequence. AKA: 1. Ignition. TTV clicks open, thermo valve sends current to auto choke hosting, earths manifold pre-heater. 2. Coolant/auto-choke heater heats the bimetallic spring in auto/choke housing regulating choke position. 3. Hot coolant expands the wax element in the waxstat pushing the waxstat rod against a pin which brings down the idle whilst the engine gets up to temp. 4. TTV functions to push plunger into midway position and you're at idle.
This guy really has a great breakdown of the carb. It's in french but Google Chrome translates the page decently. http://herlent.daniel.free.fr/reparation/pierburg_2e2_joints/
Quick and hopefully last update! Wanted to start this post by saying that the FAQs on here are a bloody lifesaver and if i was starting from scratch id knock my own head on the wall for believing i could just fix one thing or the other and hope it would sort itself out. The 2e2 is a fairly simply thing dressed up to look really confusing. That being said, you really have to work through it methodically and get every single bit checked off if you dont want to end up tying yourself in loops trying to fix it. So, whilst waiting for the new waxstat to arrive, (genuine pierburg can you believe) i installed a new pulldown unit and adjusted the two stages according to the 2e2 repair manual. Now opening and closing according to stated distances. Finished all the wiring for my two switches, massive thanks to Pete and everyone else of here who helped!! first for the autochoke and second for the manifold pre heater. Just wired up a relay system for both so i wasnt running too much through the switches and wow what a huge difference. The manifold preheater is still abit of a mystery to me in terms of what effect it induces. The big difference is the autochoke heater, when recieving power you can can see the choke open slowly and dramatically reduces the time on cold idle (fast rpms) if, like me, you have a faulty waxstat. On the ground this relates to a huge drop where cold idle was sometimes sticking for 2-3mins at 2000+/500 to now only around 1-2mins at 2000+/500. Rough or lump start has been eradicated albeit if its exceptionally cold and you drop to second in low revs. But a massive improvement where before it would take 100m to even out and now its just a second before the revs catch. I finally got the new waxstat in the post today 90 Euros from Germany, can send a link if anyone needs. Installed the new waxstat +pin and plastic sleeve and fired it up from stonecold (-2c today)... Guess what, cold idle bliped to 2500 for about 15 seconds and then dropped straight to 1600. Only downside with the manual switches ive installed in the dash is remembering to turn them off at the aproximate temps they would with the original temperature switch loom. I installed two leds so i can at least see when they are on and off. The autochoke i swtich off around 75c engine temp and the manifold heater goes off as soon as i see the need touch the first temp line (should switch off at 54c). Im going to take the car out for a solid run tonight and see how everything feels. Ive got a small split in the inner carb mounting flange that happened when the car was running on a few weeks ago during working through the 2e2 manual. But everything is now according to the book and will update if and when anything else comes up. really hope this helps anyone going through the 2e2 saga.
why not wire the relays up to the original switches? the inlet heater already has a relay as well its the one in slot 2 (ce1) or slot 12 (CE2) you could tap your switch to the trigger for that and save yourself a relay
It's an Audi 80 B2, so different setup. It's all done now and working so I'll leave sorting out the original loom until the summer
I have access to a couple of parts cars and they do come up on the market here now and again! But yeah, at this point, after a year of working with it I'm just happy the ol' 2e2 is running as it should
