...do with the idle-air valve, injectors and ignition on the over-run? I'm thinking of tinkering with my 2e2 to add the much-talked-about-but-never-seen relay/controller* that closes the primary throttle on the overrun, but don't know why VW stopped using them. All the Pierburg literature seems to imply that they were a standard fitment originally, but I've yet to hear of anyone who's got one. Did they cause problems, or was it just a driver perception issue with the accelerator pedal mysteriously moving underfoot? I'm thinking it would be nice to have a solenoid valve-controlled air inlet downstream of the carb so that you don't go straight into engine braking when the throttle shuts, but 'cruise on fresh air' instead. Can anyone envision show-stopping problems with this approach? Do fuel injected engines (in overrun conds) shut the fuelling right off? The spark? Do they wide-open the idle air valve? So many questions, so little idea! Edit: *Just got one of these from ebay.de for 7 Euros inc. P+P!
I cant answer any of your questions, but it sounds like a really good idea. Will be interested to see what comes of this!
KJet (`83` on) does shut the fuel right off using a combination of coolant temperature limit (35`C) - idle speed (relay) - throttle switch - `solenoid` valve. As I understand it: When foot comes off the throttle a circuit is completed and that providing engine revs are > 1200 and the coolant temperature is above 35`C the `solenoid valve opens - this equalises the pressure in the air intake system across the metering head flap (fuel valve) thus closing the flap (to the mixture screw setting) and shutting off the fuel to the injectors. The solenoid valve is piped between the base of the airbox and upstream of the throttle butterflies. Not sure about the spark control ? Air idle valve - takes off the downstream side of the metering head flap to bypass the throttle butterflies hence would open to maintain the idle set by the mixture screw. Does that make sense Will attempt to post a picture of my source material later ... From: Haynes Automotive Fuel njection Systems (Jan P. Norbye) 1988
Yes mate, I think so, thanks. It did take me about eight readings before I could picture it, but that's my fault not yours. I'm not familiar with the k-jet system, but I think I follow. Seems a bit unlikely that the spark is inhibited, but someone's sure to know. My reason for asking about that being that there may well be residual fuel in the (my) inlet manifold after the throttle shuts, and I could end up igniting a very weak mixture for a brief time, maybe. I've heard that this can be 'dodgy'. Appreciate your reply.
No, but I don't like wasting fuel! The 2e2 (unless fitted with the special relay/controller that acts on the 3-point unit via the cut-off valve) chucks fuel out of the idle/progression outlet all the time-except maybe at wot, and probably quite fast during overrun from highish revs. With the relay thing allowing the throttle to fully shut if revs are >1200 and foot lifted off, you go straight into engine braking, as there's nowhere (much) for the engine to get any air from. So I thought I could feed some air in bypassing the carb/throttles...? Edit: Thanks for adding the diagram, very helpful!
Where there's a will... Actually that could be quite easy, as there's a spare vac nipple below the primary throttle (I think) that's blanked off. I could connect that to a second solenoid valve (same as the one at the back of the carb) then just energise/de-energise that as the throttle opens and closes (whichever way it needs). Might not be much extra air, mind. Could even take it further...Fit a lambda probe, richen up the mixture a bit all round then add air according to what the lambda is. Or maybe I should buy a gti.
why are you such a carb nut pete.... I can't wait till the day I can bin the carb engine and I will NEVER buy another carb car again
Not sure about these new-fangled, ECU-controlled, sensor-covered Efi-type machines. I have to fix my g/f's Omega far more often than my car, and it's usually harder to fix. Still having a bit of trouble with yours then Ben? Just the choke cable bracket?
on the k-jet the spark control is as simple as it can be, so no over-run cutoff there. On the digifant there isnt any fuel cutoff as std I don't think as the ECU chip I fitted specifically mentions fuel cut-off was added. As for carbs not being as good as injection, my old 1.6 driver ran better than my digifant ever has
Just bought a book from Ebay.de on the Pierburg 2EE, which is a hybrid-type version of the 2e2 with various functions controlled by electronics, and an ECU. Seen the carbs themselves, and the ECUs, come up very regularly on there for not-very-big bucks, as I think they were fitted as standard to the 1.6s over there. Have to practice my German by trying to see how they work and see whether a bolt-on/drop-in replacement is feasible... Happened to notice a listing for some spares in, I think, new and unused condition, for the 2e2 which may be handy for someone to acquire. Namely, a pulldown unit, a part-load enrichment valve (power valve), a waxstat, idle-air adjustment 'tower', a little piece I can't identify from the picture and a main gasket: Take me there. It says "Not specified" under shipping to UK, so the seller might have to be contacted about that. Someone's just asked if the pulldown unit's working, and been told yes, tested; so unfortunately there might be at least one interested party over there.
Most european EFI type engines cut fuel on overuns and that includes digifant cars. There are fuel economy and mostyl emission related benfits that I care not to get into. Idle speed is another function that uses a PWM air bypass or a stepper motor to hit a preset idle speed. On a 2E2 carburettor things are a bit different. You have a thottle dashpot to dampen butterfly closing and a idle speed circuit that can be shut via a solenoid. The idle speed circuit will in operation during throttle plate on idle screw between idle mixture port and the prgression port pending throttle angle. If you have a means of shutting the idle soleniod as well as the,power valve if fitted, during a deaccel fuel would cease to flow. Carburettors that had this ability were called feedback carbs and had a control unit connected to a single wire EGOS, and coolant temp. These were later replaced by EFI.
The 2ee carb is a conversion kit which could be fitted to the 2e2 to make it to work with a lambda probe, I had some pdf documentation kicking about but since it was all in German and I'd likely never see one anyway I deleted it all!
Yes correct. The 2EE was the carb fitted to the legendary PN engine, which is the standard 1.6 litre Golf engine and people always rave about its reliability. It always baffles me that the Mk2 engines that were used here in the UK are all different compared to the German standard. It seems to have mainly to do with the fact that they didn't have to use CATs over here. They probably saw that as an opportunity to get rid of the old engines they couldn't use in Germany any more due to the new emission laws. Good luck with the language, Pete! Fascinating, this technical stuff but it goes way over my head. Anyhow, give me a shout if you get stuck. Maybe I can assist. Gert
