I've got a mk2 1.8 scirocco with a 2e2 carb. When cold, the revs are below 1000rpm and the car often stalls when I don't have my foot on the accelerator. Only after about 2 minutes, the idle goes up to about 2.5k to 3k rpm for 10 minutes, as if the waxstat only kicks in then. After that it runs absolutely fine at 900 rpm. And I don't know why, any ideas? P.S Full story here: http://clubgti.co.uk/forum/showthread.php?t=225888
I've read the other thread. Could you describe what happens to the plunger on the three point unit at the various points on the cold start up, warm up and then shut down. And also whether the "screwy bit!" is resting on the plunger. My guess is a vac problem, but you say you've replaced and checked the vac lines. summary cold start TTV initially (and briefly) blocks a vac signal to the 3PU meaning the 3PU plunger remains fully extended for a few seconds after start up TTV warms quickly such that it passes the vac signal on causing the plunger to withdraw to the control position (controlled by the bolt on the back to the 3PU). However the idle throttle position is now controlled by the waxstat (so there is now a gap between the plunger and the screwy bit) waxstat extends gently closing the idle throttle until the screwy bit eventually rests on the 3PU plunger which is still at the control position this situation is the normal driving conditions for the carb at shut down the over-run solenoid opens and allows a further vac signal to the 3PU causing the plunger to fully retract briefly, as the engine stops the vacuum is lost and the plunger then returns to fully extended (as it's spring loaded to do so) both the TTV and the run-on solenoid should get 12v whilst the ignition is on and 0v when the ignition is off. so if you can run through this, and then work out which bits of the process the carb is getting wrong this should pin-point the fault. A lot of pierburgs have been tinkered with in the past, I've been guilty of this also when I was new to 2e2s and didn't understand how the waxstat interacted with the 3PU So as well as a fault, you may also have someone's "fix" to contend with!!
I was having the sames problems with cold idle also which I managed to narrow it down to the pull down unit or vac hoses. Turned out that a vac hose coming off the pull down unit was split. If you do a search on the test for the pull down unit you will know if it needs changing. You shouldnt be getting anywhere over 2k rpm 2k max. The wax stat will reduce your revs as it warms up rather than increase it as you stated the wax stat starts to kick in. 2e2 with defunct wax stats idle high all the time! My guess is the pull down unit it was causing me so many headaches but it is easy to test and cheap to replace, just make sure you test the new one as it can happen! Changing all the vac hoses is a good investment you can get 3 meters of silicone 3mm internal diammeter hoses off the bay for around 7 delivered which is more than enough. Good luck!
I've had a broken arm so I haven't been able to work on the car until now. The coolant channel o-ring sounds plausible. How do I check? I don't think it's the vac hoses as it runs fine when the car is warm (even if it's been off for an hour, the revs will go straight to 900rpm when turned back on). It almost seems as if the waxstat takes too long to warm up. What do you think? Here's a video of what happens when it's fired up from cold: http://www.youtube.com/watch?v=FmseoMRopMI
Hello mate, Wish your arm well. I also have a 1.8 Mk2 Scirocco with the pierburg carb. I have already had it in two pieces cleaned out replaced any dodgy vac hoses and refitted onto a new rubber mounting plate from Volksbits. Can't seem to get your video but what you explain I have exactly the same issues. I start the car and it has to have the foot on the gas for a minute or two till it starts to idle on it's own. It is worse when really cold and until automatic idle occurs the car sounds pretty rough. Other than that with the work I have done and a good service it runs a lot better up to temp. Rubjohny you had flagged this coolant issue before on another forum with the O ring that can fur/rust up and get blocked (it was referred as like a cats arsehole lol) . I suppose the only way to check is removal of the inlet manifold which I don't really look forward to doing. This is where that O-ring is positioned between the main inlet holes. Might well just buy a head gasket kit and take the head off one weekend. Would there be any indication of the corrosion from the outside? or other evidence?, I have pictured and arrowed (red arrow) where I think that O ring is on the inlet manifold..
Video should work now. I really don't care too much about keeping the foot on while its cold, what I do care about is the stupid 10 minute 3000 rpm idle speed until it's really warm.
MacColl: Yes that is the o-ring's location, but no it isn't a VW only part, GSF do it for about a 1 IIRC. VW won't charge a lot for it though. Probably no visible sign of a problem from outside I'm afraid. If you were to take the head off, and bought a 'head kit' with all gaskets/seals etc, it should be included. Getting the intake mani off isn't all that bad though, if the right tools are used. A way to test the flow of coolant through the manifold is simply to feel the water housing of the autochoke on the nearside of the carb, it should get almost untouchably hot within about ten minutes of running from cold. If it only gets warmish after this long, the flow is probably compromised. Looks like you aren't in a position to run the engine right now though, assuming that your pic is of your engine. See also below. -------------------------------------------------------------------------------------------------------- Eggmanpete: The video seems to show me that the 3-point unit is still fully extended for far too long. Normally this would result in super-high idle almost immediately after you turn the key, which isn't the case here, your engine is really struggling, even with that wide throttle opening, for the first few minutes, by the sound of it. So something else is also affecting the cold running. You say you don't think it's a vac leak because it runs OK once fully warm, but I'd be tempted to renew all the flexi rubber ones, including those tatty-looking items going to the airbox thermostat in your vid. I'd do this as a matter of course on a misbehaving 2e2-carbed engine. Don't forget the distributor vac connection either, check that the diaphragm of the vac advance unit on the dizzy isn't leaking too. I think a vac leak (anywhere) will make more difference to running when the engine is cold, as it's having to work a lot harder to keep itself going than when its all nice and warm. So it will be less tolerant of wrong mixture when cold, which is what a vac leak will cause. Did you ever try this suggestion from the previous thread? If you're sure the TTV is getting powered OK, and there really aren't any leaky hoses, that's about all I can think of that may explain the 3PU's behaviour. (Especially since you've tried two different 3PUs). Also check the resistance of the TTV, should be around 7 or 8 Ohms ballpark, to rule out failure of the heater inside it. I don't think it's a waxstat issue.
It's the not knowing that kills me with these carbs. Firstly your video shows you might need one of these for the front of the air box.. http://cgi.ebay.co.uk/VW-GOLF-MK1-M...arts_Vehicles_CarParts_SM&hash=item2eb013533c I would also be looking at all the vac hoses as I also thought they looked quite old on the air box. I'm actually going to look over mine again just in case. My car is just like yours from cold (tappet noise included) but it never races in idle just raises after a minute like it should from the off and settles to around 900 once fully warm. Thanks EZ Pete, my car is actually being driven daily now so I'll see how hot that housing gets and take it from there. As mentioned I'll be checking over every vac hose again. One thing that springs to mind though is my temp control flap doesn't function. It was actually screwed shut and now is wide open constantly (not good in cold damp weather I know). I should maybe block the vac hose that leads to it in case it is loosing air through the fault with the diaphragm part of that?
Ok, I'll get some new hoses and try that again. What I do also find odd is that if the engine isn't quite warmed up yet (5 mins or so) and idling at 3000rpm and I kill ignition (also need to lift clutch so it doesn't run on) and then start it again, it often idles at 900 rpm straight away. What would that mean for the 3p unit?
Dunno, maybe the sudden changes in vac conditions as you power off, then on again is enough to jolt the 3PU into its correct position. Here's a piccy of the teeny-tiny orifice in the vac port that drives the 3PU. You can imagine it could partially block up fairly easily. This piccy is after running a 0.6mm drill through it, which pulled out a fair bit of crud. Couldn't get a 0.65 through, felt like it would be cutting metal. MacColl: I'd be tempted to wedge the blend flap in a 50/50 cold/warm position until such time as you can find a working one. Edit: And yes, air/vac leaks are the enemy, so block off any hoses going to suspect diaphragms, surely.
This is all good stuff, eggmanPete I hope you get to the bottom of your issues and I'll be methodically checking through mine. I'll add and correct that my car seems to settle at 800rpm not 900 which I believe is correct. Did experience carb freezing one early morning last week but was able to cope with it as it only occurred on a small stretch of duel carriage way. Will probably wedge the flap in the short term. Thanks EZ Pete
The 'correct' idle speed is not clear to me. Somewhere between 750 and 950 will probably be fine. If the engine idles happily, and doesn't shake the car about, then it's down to personal preference I reckon. I have a suspicion that the front engine mount may have something to do with the different figures found in different manuals. I don't know, but I have a feeling the earlier mounts were just rubber, later ones hydraulic, which might account for shifting idle speeds around to keep away from natural frequency of the mount. Maybe. Could also be to do with emissions regs, but I think the lower 750 figure applied to older MK2s, and it would seem to me that lower idle = lower emissions, so that wouldn't add up. Unless I'm missing something. Rubjonny'll probably know. I have a funny feeling too that a degree of carb icing can happen without even being perceptible to the driver, except by worse-than-typical fuel consumption. Best avoided completely by having a fully functional system.
i've replaced the vac lines and the problem is still there. 3000 rpm idle after 2 minutes of warming up from cold which lasts about 10-15 minutes. I can't get to the tiny port at the moment, but I'll try to fit a drill bit in there to see what happens. I'm no longer convinced that all the VAC lines are in the correct placement, here's two video's of a strange whining noise it makes all the time, I just noticed it stops when I take the vac line off the green resevoir. Does it sound familiar to anyone? http://www.youtube.com/watch?v=Iq35TX3gGbw http://www.youtube.com/watch?v=aLFaRqgrVC8
I think you're homing in on your air/vac leak by following that noise. My best guess would be the flexi hose that couples the rigid airbox vac hose to the pipe stub just to the left of the circled one in the pic a few posts above. But you've changed that, right??? I guess the rigid hose could be boogered... Can't see it being directly associated with the stage 2 vac unit, but anything's possible. There shouldn't be much suck at all on that hose except at large throttle openings. Another possible is the larger flexi vac hose that couples the inlet mani to the brake servo vac pipe, check that too, especially on the underside where you can't see.
I've disassembled all hoses and put them back together, also replaced the twisty thing on the pull down unit and the noise has disappeared and the car runs smoothly from cold now, not the juttery way it was before. The 3000rpm when cold remains though when the waxstat takes over, so for now, I've put a washer between the waxstat and the carb just like I used to do on my golf and I guess I'll find out tomorrow morning (when it's cold) if it has worked or not. Thanks for your help as always!
Gald to hear the rough-running start-up has been resolved. I'm confused about your waxstat situation though. When you say "space it off with a washer" do you mean the whole waxstat housing, or effectively increasing the pin length by putting something on the end of it? The reason I ask is that the way it works is that when cold the pin is at minimum extension, which causes the widest minimuum throttle angle (and therefore highest idle revs). As the waxstat warms, the pin extends, moving the cam round and so reducing the minimum throttle angle, and the revs. So you should find that if you space the whole waxstat further off the carb body, it should make revs higher. Anyway, you haven't yet convinced me that the TTV is working right; have you measured its supply voltage and its resistance? IME 3000 rpm is higher than anything the waxstat can achieve, even if it's missing completely (unless the general set-up of the throttle plate has been monkeyed with). Best of luck anyway.
Yes I did notice that when I put the washer on, and realised I did it on my golf to increase revs, not decrease them. At least this has shown me that the waxstat has nothing to do with the idle revs, I'm testing the TTV in a mo and I'll report back. Just want to point out this is completely temperature related, it was -2 degrees outside on the way to work where in 15 minutes the engine idled at 3000rpm the entire way. On the way back from work with 8 degrees outside the engine idled at 2500 ish for 2 minutes and then dropped to 1200rpm and then 900rpm.
