Yet another pierburg problem I've got a 1988 mk2 golf 1.3 with a 2e3 on it. When its started from cold, 95% of the time it will "chug" for a few minutes before the revs even out. It'll usually need revs held on it to keep it going until it evens out (Or else it just stalls). I've followed the guide on here for testing the pull-down until, and it does seem to loose vaccum slightly when the top hole is blocked. Is this problem most likely to be the pull-down unit? Cheers
Could be that the pulldown isn't opening the choke flap far enough, fast enough. Best bet is to get an assistant to start it (from stone cold, with semi-automatic choke primed as per manual) while you watch with airbox lid removed what's happening with the flap. It shouldn't need any accelerator-pedal-help to keep running if the autochoke is all working right, but if it does, get your assistant to use the minimum possible to keep it going for the experiment. Should open to the first stage really quick (like 1 second from when the engine catches) and move onto the second stage within a few further seconds. If your 2e3 has a TTV connected to the pulldown, as I think it will have, this time will vary with outside temperature, the colder it is, the longer before it opens to the second stage. Got to get the fire lit now. Don't buy a new pulldown 'til you've done the above check, and I've had a delve in a cupboard for where I think I have a tested spare. Edit: found it, in only the third place I looked. If you find that you need it drop me a private message. If it's anything other than super-simple to replace, I'll do a teeny-weeny 'how to' as I remove it. P.S. As you're new on here (welcome!) don't be too surprised or alarmed if any replies you make to this thread don't appear immediately. Your replies have to be hand-approved by a moderator until they're sure you're not a spammer. Edit2: Also, have a read through this thread where I learned about the mechanism that should be holding the revs up on yours during early warm-up, so that the accelerator-pedal action is unnecessary. It might be that this is gummed up and sticking in some way opposite to the problem Bigman10 was having.
Thanks for the welcome! I tried what you said, started it by the manual and it ran really lumpy (Needed accelerator to keep it alive). When I opened the choke flap by hand it improved it greatly. I think it went to position 2 after I opened it, which seemed fairly quickly after position 1. Still ran slightly lumpy at stage 2, and better with the flap open completely.
Just to update on this, I bought a new pull-down unit from SEAT (Cheaper than VW!) and it seems to have cured the problem. When I started it for the first time after changing the pull down, it went straight to fast idle (2100rpm), but hasn't done so since (I *did* only change it last night tho). Still runs fine anyway, starts at about 1200rpm and works its way down to about 700.
Still OK? Hopefully that was all it was; the 2e3s are a lot more reliable, long-term, than the 2e2s, I think. Do treat it to some carb cleaner occasionally though, it's cheap and it works.
Runs ok, but I think the choke needs adjusted a bit, because its only been at fast idle once! EDIT: How do I take the choke housing off? I've had the screws out, and it looks like there is a big spring in there, don't want it falling out
Cheers Pete. I'd just like fast idle, it still runs fine without going to it (Maybe i'd be better leaving it alone ) .
The position of the choke-flap does not directly affect the idle speed, it just attempts to keep the mixture approximately correct for the temperature of the engine, during the cold-start phase. What directly affects the idle speed during this time is a stop (pink arrow) that bears against a stepped cam (blue arrow). Please ignore the big spots of colour near the top of the pic, just my clumsiness with Photobucket. View is upwards from the base of the carb: If everything is working as intended, this cam initially is on a 'high' step which holds the primary throttle at a relatively wide minimum angle (compared with its fully-warmed-up state), this gives the engine more fuel/air mix so it revs higher. As the bimetallic coil spring in the autochoke housing warms up, this cam should rotate round so that the stop lands on lower and lower steps, reducing the throttle angle a touch with each step. If this cam, and the mechanisms that physically open/close the choke flap are not free to rotate easily, the bimetallic coil spring, and some other little springs in behind the autochoke housing, may not be able to move them into the correct positions at the various stages of cold start. It sounds to me like yours is a bit sticky, and this stepped cam isn't moving into the right orientation for cold start. I'll show you why this might be happening in another post, tomorrow. This little bent metal rod is what ultimately pulls the choke flap open: Red arrow shows which way it moves to open the flap as the engine warms up, blue arrow shows the way it moves when the mechanism is 'set' by fully depressing the accelerator pedal, then fully releasing it slowly, before cranking up for a cold start. You'll have seen this stuff when you removed the whole autochoke to change the pulldown unit. When you open up the autochoke housing, you see the bimetallic spring, and the plastic peg it rotates round with it as it heats (red arrows) or cools (blue arrows). The overall 'strength' of this spring to open and close the flap is affected by the rotational position of the whole housing. There are some lines on the outer bits which should be lined up: Not too sure why there are two lines on the metal part, one scratched in, one raised. Try one then the other and compare what happens on consecutive cold-starts. If this alignment were miles out, it might explain your symptoms. Before I go any further into the ins and outs of the choke mechanism, there's something else, completely unrelated, to rule out. The carb sits on a rubber mounting flange which seals it to the inlet manifold. If this flange leaks air due to being old and perished, it will reduce the amount of 'properly fuelled' air that is drawn out of the bottom of the carb, so the overall mixture reaching the cylinders will be too weak, which might result in lower-than required revs for cold-running. This is what the flange looks like: Try lifting (gently) and rocking slowly from side to side, and front to back, the whole airbox/carb with engine running. If the flange is leaky this treatment should give obvious changes in idle speed.
OK, are you sitting comfortably? Here's part 2... What I noticed when I removed the whole autochoke 'chunk' and then the water-piped bit off that, was that the plastic peg that the bimetallic coil would try to turn was quite 'sticky' and not really what you'd call "free to rotate". [:^(] This is the chunk: It's rather complex! Imagine, on a Pierburg carb. Parts labelled A, B, C, and D can all move relative to one another, with part C being the only one directly coupled to the peg at the right-hand end (out of sight) that the bimetallic coil tries to move. A and B are both 'loosely' coupled to C by two small springs, allowing relative movement. One end of each spring is attached to part C where the two random blobs of blueness are. Part A holds the stepped cam, and part B is what moves the bent metal rod that actually pulls/pushes the choke flap, and is acted on by the pulldown unit. While it was all up together I couldn't work out what was causing the 'stickiness' so I took it apart (after unsuccessfully attempting to free it with carb cleaner and 3-in-1). There are a pair of little tabs that squeeze in together (purple arrows), and then having disconnected one end of each spring the whole thing slides apart. Then when I re-assembled it bit by bit, I found that it was only part B that was sticking on the central shaft. I'm pretty sure that the cracks in the plastic, where metal bits are pressed into it, are the reason: Although you might expect the cracks to open up the central hole and so make it looser, it definitely only became 'sticky' as the cracked bits started to engage. Now I'm not saying for sure that the same has happened to yours, but I wouldn't be too surprised. You'll be able to observe any such cracks without this radical disassembly, and whether it is 'sticky' or not by just attempting to rotate the 'peg' that the bimetallic coil engages with. (Once the chunk is off the carb, to remove the interactions with the various parts it works with) Because of the complex way that these bits move relative to one another, I can easily imagine that this stickiness would stop the semi-automatic choke function from 'setting' correctly as the go-pedal is pushed and released prior to cranking. Edit: Doing this 'pedal action' very slowly will probably maximise the chances of everything being able to rotate into the right positions even if things are a bit 'sticky'. Try it. Whether it can be repaired from this cracked state, or whether any can be found uncracked in scrapyards, I don't know... The actual bit that has cracked has its own individual Pierburg part number: 5 21642 03, on this one. I'm not sure I'd be confident of a helpful response from Pierburg if one were to ask for one...If anyone reading this knows anyone at Pierburg, I'd be glad to be put in touch though, lol. It may still be possible to buy this whole chunk new, but I imagine the cost would be prohibitive. Do let us know what you find, Sam, if you decide to get 'in amongst it'.
I haven't been brave enough (Or the engine cold enough...) to take off the autochoke yet, but do you know the pulldown gaps for the 2e3 on a 1.3? (Just thought mine may be off after changing the PDU) Cheers
Well the answer isn't clear to me at all... Haynes Golf manual (1081) states only "Choke valve gap 2.0 +/- 0.1mm", which doesn't make too much sense in light of the following. The Haynes Pierburg manual (1785) suggests that yours, 1988, is going to be a 2G or NU engine code, possibly MH but that one's listed as 1985-1987 so maybe not. The strange thing is that apart from a catalyst-equipped 2G (1990-1991), all the above list only one pulldown gap, the "a1" value, which is the second stage of a 2-stage pulldown. The a1 dimension for 2G, NU and MH is given as 2.4 +/- 0.2mm. No dimension is suggested for the first stage "a". I'm sure you mentioned that your pulldown has two vac hoses, making it a 2-stage one. So, I'd set it so that when you suck on the vac hose that would connect direct to the carb body, and block the other one, you get the choke flap open to 2.4mm, measured at the lower edge. Some piccies of your carb may help, especially from above perhaps with airbox completely off, as well as confirmation of your engine code.
My engine code is MH. I checked haynes and it confused meonly mentioning 1 gap, and not the 2 stages. My PDU is the same as the one in your guide on testing the 2e2 one..
The pulldown could well need adjustment rather than being right 'out of the box' for the following reason. If you look at this piccy: The bit that the pulldown unit pulls on is the little metal bit right below the letter "B". As you can see on this carb, that part has been bent (downwards in pic). I'm sure it was originally on the horizontal axis of the pic. The bending is also possibly what's caused the cracking of the plastic part it's anchored in. You could try to bend it back, or move the two adjustments on the PDU to compensate. Try the latter first, less risk of busting something, I think. If you find that 2.4mm doesn't work particularly well, try instead setting it up as per what the Pierburg manual suggests for a catalyst-equipped car. First stage gap (adjustment is the round black knob) = 2.4mm, second stage gap (little allen screw adjuster) = 4.0mm. My gut feeling is that these numbers make the most sense of any I've seen in these books. Adjust the first stage while sucking on the lower vac hose with the top one open to air, and the second stage with the top one blocked.
Cheers Pete. I just tried adjusting it the way you said. I disconnected all of the vaccum pipes from the PDU, and sucked on the lower one (With a bit of pipe obviously..), then used the black knob to set the gap. When I blocked the top hole and sucked on the bottom, the gap was still the same, and adjusting the allen screw has changed what happens on the first stage (Sucking bottom vac pipe, top open to air)
I'll have a play around with the 2e3 I've got here a bit later, and see whether I can shed any light on this.
Don't know how I didn't spot it, but I've got 2 stages now, the allen adjuster was so far in that it was hitting the stop on the first stage
