So had a full day at it today and figured i would continue the thread Been reading more and more about the 2e2 and i hope this troubleshooting guide im writing will be of use to someone in the future. The biggest issue i am having is the 3pu taking far too long to go to the idle position during startup. it was 20c today and the whole startup process was as follows: 1. ignition, revs blip straight to 2000 and hold there. 2. 3pu retracts fully. 3. Revs hold at 2000 for around 2mins (3pu plunger still fully retracted) 4. Revs start to dip after 2 mins and slowly lower to around 16-1800 (3pu still fully retracted) 5. Revs continue to lower until they reach around 11-1200 6. 3pu now extends the plunger in idle position. 7. Revs now hold around 950 8. First couple of hundred metres the car will run rough at low revs. 9. Car now runs fine though is hesitant when feathering accelerator in 4th. 10. Idle also acts slightly erratic moving between 950 to 800 completely randomly. 11. If the idle drops to 800 if i break the revs drop right down to almost stalling. 12. After running for 10mins or so all these problems disappear. After driving, i can restart the car and it does the starting procedure textbook, i.e, blips to 2000 and then drops straight to idle and runs without any lumpiness. Because of these issues i have started to troubleshoot the entire carb, but i figure the issue is with the cold start in the mornings/after the engine has fully cooled down and have found the following problems starting from the top. Anyways, i have been writing a pretty comprehensive list of everything that needs checking/replacing and heres where i am at so far. Mounting flange - I replaced mine less than a year ago so all is well there. Though what i have noticed is one of the fixing bolt has somehow gone missing. That could certainly cause an air leak and give a good clue to the hesitation i sometimes feel when feathering the accelerator. Vacuum lines - Finally got some decent quality vacuum lines delivered to switched out anything that was even a little suspect. Its really worth getting decent lines as the first lot i bought were silicone and i noticed they really didn't seem up-to the heat the manifold puts out. https://i.imgur.com/ocCvJvv.jpeg PDU - After doing the vacuum test i see that both positions are correct, though i notice when blocking the upper port to adjust the second (larger choke gap) i am able to continue sucking air through the system. So if i close the upper port and suck the lower the choke moves to the larger opening but i can continue sucking a small amount of air through. Not sure if thats supposed to happen... probably not. Autochoke - Doesn't receive 12v when tested from cold in the morning. Housing on the unit does get boiling hot after a few seconds so i am confident there is adequate coolant flow. During the winter i turned the housing as far anti-clockwise as possible in an effort to get it to run better from cold. It used to sound like it was running on three cylinders and adjusting the autochoke housing helped. But now its summer and its been bogging down during start up for the first few hundred metres and i noticed the choke flap was not returning to its resting position overnight. I figured that was because the choke flap was basically fighting against the bimetallic spring and was obviously losing so i have taken the housing back to the original notch settings whilst i troubleshoot the rest of the carb. Seems like an issue with the autochoke not receiving 12vs. I heard that the coolant flow is the biggest contributor in expand the bimetallic spring and thus controlling the choke flap but surely the small heater in there not receiving power might be having an effect on my cold idle speed sticking high for too long in the mornings. https://i.imgur.com/Xk3TzqZ.jpeg Manifold preheater (hedgehog) - Not receiving 12vs. Tested both when cold (below 15c) and when hot after driving. I really do not understand the manifold preheater instructions in the Haynes (says the manifold preheater switch should be switched off below 35c and on above 65c). Surely if its cold the preheater should be on to vaporise any leftover fuel or am i getting this completely wrong as that is just the switch and not the actual unit? I figured that perhaps one reason why i am running lumpy and bogging down in the mornings is because the manifold preheater is not receiving power and is therefore not vaporising any left over fuel... Waxstat - Unfortunately one of the retaining screws has absolutely stuck fast so i am going to have to cut it off tomorrow. I have dunked it in boiling water a couple of times now and the pin sits at the 2mm/8mm points happily. it also gets hot to the touch at the same rate as the autochoke housing so i am hoping there isn't an issue there. 3pu - The overrun cut off solenoid/valve is receiving 12vs and makes an audible click when you turn the ignition on. Also during running (at warm) if i adjust the choke flap i see the plunger on the 3pu retracting fully/extending back as it should do to prevent too much fuel getting into the carb. The 3pu also goes to idle position during start up sequence. https://i.imgur.com/xJTiMpK.jpeg Overrun cutoff solenoid/valve - Receives 12v and makes an audible click when ignition is turned on. Plunger retracts momentarily before extending fully on shut off. Can also see the overrun working if you blip the throttle, over 1200 the plunger withdraws fully and then extends once again. TTV - Receives 12v, though it doesn't click like the Overrun valve. Found this a hard one to test. All i can say is that it has 12v and the plunger extends to all three positions. Thermo switch - Because the autochoke and manifold channel heater aren't getting any power i located the Thermo switch (which is slightly different on the Audi 80) and began probing. Here is a picture of the thermo switch in the Haynes https://i.imgur.com/ajvb6Sd.jpeg and here is how it look IRL https://i.imgur.com/XX10w08.jpeg Because im really not that bright i cant seem to figure out what probe is what! In the manual i have (starting from top left) R C T +. whilst on the sending unit it has nothing written by any of the senders. According to the Haynes: + Positive should be at battery voltage, C (Auto-choke thermo-switch) at 33c or below should be "on", so i guess receiving 12vs. Above temp of 43c is should be off. R (manifold preheater thermo-switch) at 35c or below should be "off" so no power and with the temp above 65c is should be switched on. T No idea what this plug is for, doesnt say anything in the Haynes. Anyways i went ahead and tested the sender, though i couldn't for the life of me figure out what plug was what. Ive labelled the units orientated from my birds eye view. If anyone can help me understand what plug is what according to the Haynes that would be a big help. Top left plug 12.2V https://i.imgur.com/qKid559.jpeg Top right plug 2.45V https://i.imgur.com/ys5x0Re.jpeg Bottom left 0vs https://i.imgur.com/7e5XNVk.jpeg Bottom right 12.32v https://i.imgur.com/9wOIDpm.jpeg
There's a lot to digest there, but a few things jump off the page. The flange mounting missing bolt, sort that before doing anything more technical. The 3PU should only go to full retraction at/during the moments of shutdown*, as far as I remember, which means there's something odd going on there, possibly with the vac hose routings, or the overrun/shutoff solenoid, I'll need to remind myself how that all works. When you say the waxstat has the right 2mm/8mm protrusions, are you measuring from the flange face, or the top of the brass cylinder? Are you loading the pin with the suggested force at the time? *Edit, that may be different on the Audi version, but I think is/was true on the Golf2.
Weird thing with the TTV is that it does go to the idle position, so the vacuum operation is in effect working, just very slowly. I'm going to go out in a minute and take a look at the 3pu once the cars been warmed. I want to see if the TTV puts the 3pu straight into idle position from cold or what's going on there. I've checked and double checked line routing and all seems good but if you want to take a look I put a picture link on the OP. I think the flange is a good place to start, perhaps it's no creating a good seal which is throwing everything out. Just a quick question, do you, off the top of your head remember what bolt size/thread type fits the flange. Same with the waxstat screw? Ill buy those today. As for the waxstat, one screw has totally sealed and started to thread so going to have to break out trusty Dremel and cut it off. I can't remember where I measured the pin from and I didn't measure the force. Once I get the screw off/replaced I'll measure the pin, though so not quite sure how to measure the force (what tool is good for that?) Cheers;
Carb mounting bolt trio are M6x109mm long, N10243001, £4 or so plus VAT each at VW, apparently. Could probably use studding and a nut instead. Or...if you mean the four that bolt flange to manifold, M6 x 15mm? Waxstat screws are M5x18, and I recall them being easily damaged due to Philips head which tend to mangle with pozidrive tooling, and awkward access, at least on the golf.
I think the force suggested for waxstat test is quite significant, like 20N, so imagine a 2kg weight sitting on the end of the pin, with it pointing vertically upward.
I'll buy the screws tomorrow so I can fix the manifold flange properly and Dremel off the threaded screw to test the waxstat. Will update when I've done all this. Thanks for all the help
Took off the carb today and would you believe it the gasket had a nasty tear on the inside. Luckily I had a spare so cleaned up the seals and switched it out. https://imgur.com/Ifsv9fb Also managed to get the waxstat off today. It definitely had some green stuff round the pin hole. Wasn't sure if that was rust or wax. My hands were so oily I couldn't feel if it was wax or not https://imgur.com/znMYDe7 Cold, It was withdrawn about 2.7mm (flush from the mounting). After boiling it extended to 7.8mm. (took about a minute + for it to expand fully.) https://imgur.com/gallery/SkaNht8 https://imgur.com/gallery/6XzvaZY Wasn't sure how to test the force it pushes still. I reinstalled it after it had cooled down for 10mins and noticed the pin was still pretty much fully extended and when I mounted it and pushed it flush the pin receded to its starting position. Tested the PDU again and it feels like something isn't right there. The choke feels very slack when cold (i understand they have quite alot of play). Hard to test the unit as with so much play I had to hold the choke flap shut lightly then create vacuum. If I block the top port and draw a hard vacuum then it swings almost wide open. Creating a small vacuum open the choke to what looks like the right gap distance. Also, If I break the vacuum I can certainly hear a distinguished air equalisation so perhaps it's holding vacuum. Here's a small video of the situation. Put it all back together and started her up. Same starting process, 3pu plunger retracted fully. Then takes around 2mins for the revs to drop down to 1600ish (waxstat doing its job there I guess) but the 3pu plunger stayed retracted. Finally after say 4mins the revs settle and the 3pu plunger extends to idle position where it sits happily. TTV is absolutely getting 12vs as is the idle cutoff valve. Did notice the hesitation and erratic idle/dipping when breaking seems to have disappeared with the new gasket.
I think waxstat is your primary revving problem. Just spent a while fruitlessly searching for the relevant image in my vast collection (poorly organised in 2e2 days) but the information I recall is that the protrusions should be measured from the flange face in both temperature conditions, and with 20N of force attempting to resist pin extension. Edit: see here Checking the waxstat | Club GTI Your first, cold image seems to show the pin approx flush with mounting face, with no force on it. This is why the revs are so high. It should already be 2mm proud of the flange mounting face, and stay there with 2kg of weight sitting down on it, if it were held vertical.
Cold measurement was taken from the flange face, so it was 2.7mm protruding. I want to get the waxstat super hot today and make sure the pin doesn't retract when reinstalled. I guess if it does then it's faulty as it should exert enough consistent force to depressed the pin that operates the throttle spring. I have just found someone selling some 2e2 spares so ordered another TTV, 3pu, Pdu and waxstat... All untested so they might all be buggered. Did you get a chance to watch the video I posted, the PDU operation doesn't seem right to me.
Try the cold measurement again, done as per the instructions on that link I found, loaded with 3kg. Bet it goes straight back flush with the mounting face, or sub-flush if you arrange the loading such that it can. Unfortunately, any factory original waxstat is going to be broken by now, and new replacements are going to be more or less impossible to find. Will watch Pulldown vid now.
Pulldown seems to be doing roughly what I'd expect, possibly opening a bit wider when top hole blocked than it ought, but it's maybe all interlinked with choke spring adjustment and stuff. Doubt it's causing any issues.
Right, well at least that's another thing I can check off for the moment. I'll test the waxstat as per your link. Next is trying to figure out the thermo switch. Still not getting any voltage to the hedgehog or autochoke.
If it comes to it you think it's smart to just wire the autochoke/hedgehog to the ignition. Perhaps even put a couple of switches in the cab so I can turn them off after startup process is finished? Guess a 15a fuse on each would work
I had a look in my collection of circuit diagrams but couldn't find one that covers a 1985 Audi 80, not sure if @rubjonny can help with that? Would really need that as a starting point to work out how the thermoswitches and probable relay for manifold heater are wired.
Ive sent him a message so we'll see I bought a couple of switches today so I think I'll just bypass them and have two manual switches for the time being. Not 100% sure on what fuses will be adequate though. The hedgehog has a pretty staunch wire...
Following this thread with great interest, only recently purchased a very low mileage 1.6 and after replacing heating matrix and bleeding the coolant system I've all of a sudden got an issue with an engine that doesn't want to settle down, starts fine, but engine revs at idle are ridiculous must be around 3000 revs. Checked all the usual things like hose's all appear to be connected,even changed both thermo switches but still the same. Sprayed wd40 around carb no sign of pulling in air. The discussion around the 3pu and waxstat seems the next obvious place to go next. In terms of the 3pu we're should this be sitting before start up and then once engine is up to temperature. Any help and guidance much appreciated as the noise from the engine over running is horrendous
This basicallys describes the full startup process. Also check out rubjohnnys pierburg 2e2 troubleshooting guide, it's been a life saver in terms of where to start.
Have you checked fuses and the carb earth wire for intactness? Missing earth would mean the TTV not getting power, I think? Whereabouts are you?
From memory, 3PU plunger should be fully extended before start-up, then if TTV is working it should withdraw to some midway position a few seconds after cold start, away from the cold idle screw shown in the images above. If it doesn't retract at all, that's why revs are staying crazy-high.
