I have a '91 Mk2 Golf 1.6 carb which has done 20k in my first 12 months of ownership, having previously done only 5k/year. Since about 6 months ago it has been choking and stalling first thing in the morning, only settling down after a couple of miles. It also runs on for a few seconds after ignition switch-off, and although it has always done this, it seems to have got worse over the same 6-month period. My Haynes manual gives 4 possible causes so I'm interested to know if anyone has any preferences as to likely cause.
Additional info:
- the engine has a slightly high idle speed
- I've changed the oil and filter every 6k
- for the first 6 months I used Optimax almost exclusively, but for the last 6 months my girlfriend has used a variety of cheaper fuel.
Would anyone suggest any of the following?
- Fuel additive/cleaner
- Optimax only
- carb adjustment
- anything else
Thanks very much
{edited to make use of drop down menus that weren't previously available at time of first posting}
Edited by Dynamic Dave on 30/10/2008 at 10:08
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Hi VW carbs are known for developing faults. I think they are Pierburg units. To me it does not sound like a fuel quality issue rather a faulty auto choke unit and/or innacurate timing. One question when you fire her up from cold how does she behave? at what speed is she idling and if you rev her during the period when the cold start is one does she rev smoothly?
If the carb is faulty most people suugest replacing faulty pierburg carbs with repalcement webers with manual choke units.
It could also be a faulty fuel pump?
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high idle is generally caused by a faulty waxstat, thats the metal thing on the front of the carb with the two water pipes attached
high idle may also cause run on
this should be your first mission, you'll probs uncover further problems once this is fixed though but you'll be on the way.
your choke problem sounds unrelated but could be a leaky pull down unit. thats the black plastic thing just above the waxstat.
difficult to tell without seeing the car but that's what it sounds like.
simply adjusting the carb settings won't improve things so you'll be looking at a bill whatever (probs about 60 quid for the parts)
or a new webber can be yours for 160 quid
up to you
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Hi, i have a mk2 golf 1.6 1990 driver, today i had those wraxstat things changed at my mechanics they came of my donor car which sits in his garage, but its not made a difference. it sounds like a subaru and will sometimes completely cut out in the cold, sometimes the temp wont warm up even after 20 minutes driving but will after 20 minutes standing if i keep my foot on the revs. i have tried revving high with the clutch dipped at various speeds which seemed to work at the beginning but now doesnt make a difference in the slightest, the car also jerks ridiculously when for example doing 40 mph in 4th gear and only stops if im constantly accelerating, which after a certain becomes illegal so im pretty stuffed at the moment. depending how its feeling she will usually have a lot of crap coming out of the exhaust, sometimes black or dark grey and it u leave it standing the road where the exhaust is near will turn black. it sounds almost as if there is a blockage somewhere. water and oil are fine but petrol consumption is disgraceful, it will do about 50 miles on £20 when it used to do about 140. would be great if you could give me some feedback. im completely baffled and love her too much to get rid, thanks katie
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from your description I am pretty confident that your carb is overfuelling which may mean there is a choke fault. A choke problem should be easy enough to fix so let's hope so anyway.
When the engine is hot the choke flap should be fully open, you'll need to remove the airbox to see this and the choke flap is the brass flap at the top of one of the venturis. It should be open at all times when the engine is hot, regardless of revs.
If its not then you're autochoke is either bust or not getting power from its electrical connector and perhaps also the coolant channels are blocked in the inlet manifold. Don't worry too much about the coolant for now, just check that the auto choke (metal dome on the passenger's side of the carb) is getting hot and that it has 12v at it's connector.
Also the pull-down unit may cause issues during warm-up. If the engine runs badly when hot this is probably not the cause but if your problem is onyl during warm-up then the pull-down is a likely cause
let us know how you get on
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IT SEEMS YOU know a lot about carbs and mark twos can i run this one past you?
I had a problem with high idel before xmas so i took my car into gragra and asked mechanic to clean carb out and turn revs down which were high.
He did this and the car was still running on and actually banging at the back as neat petrol was coming out.
I took it back and it turned out a piston was sticking at the front of the car, once we puta bit of wd40 on the car would start high and then this piston would kick in and get the revs down so it stopped the run on.
Only thing is in the mornings the car will stall once i come down the gearbox takes about 3/4 mins to truly run properly. Is this the carb knackered aggain or is this coz the revs are low
once wamred up is fine
how much for a weber carb think mines a pierburg 1991 1.8 driver and how much to fit fuel injection
should i change the fuel filter and how much for this?
when i chnage into second gear it crunches. no toher gears are a problme, is this gearbox or clutch clutch is cable operated and had been crunching for a year
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katie
You have a thermostat-related fault. If the engine doesn't warm up properly; then the choke won't come off.
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hi i'v got the same car with exact same problems! its manual choke, is sorted yet? if so how? its costing me sooo much in fuel at the moment! thanks george.
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Katie,
have you had any luck fixing this problem???
You have explained exactly what my car is doing except i have a weber and have replaced plugs, leads, coil, dizzy, fuel pump etc.
Thanks
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Similar problem,
Firstly over heating and no heat from the heater in car. - Presume no water presure - Air lock.
Secondly, Engine runs on fast idle for over ten minutes, and then erratic once driving. Presume a fault with Carb vacuum pipe off or faulty carb?.....
My pressumsion after investigating further and reading posts in this thread. If the the engine cooling/heating sytem is damaged (which mine is) it will actually have a big effect on the idleing, normal running speed and cold start/choke functioning. . This could lead to faulty diagnostics eg. cosidering incorrect Carb settups.
After investigating i found a leaking elbow joint on route to heat exchanger/heater. Preparing to fix that and try and clear any air locks. Will run the engine with expansion cap off and check water level drops, topping up if needs be.
I'm off to sort my water leak!
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woozler
I'd wonder if the impeller on the water pump was functioning too.
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I'd wonder if the impeller on the water pump was functioning too.
Ive sorted it, cheers! I dismantled the pipe work and replaced the elbow which i picked up from GSF car parts Southampton(£5.00). The plastic elbow had degraded and cracked. Now the car has returned to all its glory. The idle and normal running speed is correct. The car warms up correctly and runs around 2'000rpm and once at normal operating temp returns to 1'000rpm. There is no more erratic behaviour. LOL>> woozler
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There is a massive, informative thread on Pierburg carbs - which should help give you some more pointers. Search under 'Pierburg carb'. Have been there myself and found the vacuum ports blocked on the front and rear of the carb body, caused the same symptoms. These need clearing out with a 0.5mm drill. Good luck.
Andy
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it was the first couple of miles statement that pointed towards the waxstat, when the engine is warming up the idle speed is not controlled by the vacuum system but by a mechanical system based on the waxstat.
High idle when the engine is hot would likely be a vacuum problem, either blockages or split pipes
relativel easy to clean the carb up, just remember to note which pipes connect to what or it is easy to screw up with wrong vacuum connections ;-)
cheers
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Before you try anything more expensive, spend a few quid on a bottle of VW's own fuel additive (part number G 001 700 03 -- you might need this because dealers seem woefully ignorant of its existence). I had similar problems with an Audi 100 and it cured them overnight, after repeated attention by main dealers made any impact whatsoever. I have used the stuff ever since and I thank HJ for the original lead to it. It's particularly good at counteracting the effects of short-trip driving and it does seem to boost fuel economy too.
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I have had problems on the auto-choke pull-down unit of my mk 2 Polo, which uses a similar model Pieburg carb. Shouldn't be too hard to track down, most independent garages are accustomed to seeing these come in running badly.
While it's not really related to all this, have you checked the crankcase breather? It feeds from the back of the block into the airbox. They clog up over time and won't help your cause.
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i have a g reg mk 2 driver aswell and have the same problems i have adjusted the timing and no change , i also have replaced all of the breather pipes on the distributor and the car will constantly idle high and also splutter on cold mornings or when it is damp. i have changd the distributor for a brand new one also car and arm . im just about to do the leads and plugs but will this make a difference to the idle speed , any help will be profusely appreciated and the fuel is costing me a bomb i love the car and do not want to get rid of wat i think could be a simple proble. thaanks keiryn
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The carbs on these 1.6 and 1.8 engines need setting up properly and from cold. Not 2 hours after shut down, but first start from overnight shut down. At 100k+ it could be more economic to put a Weber on. Take it to a VW indy (or ask your local VW dealer if they have someone old and experienced enough to do it - and take the vehicle in night before). It needs a partial strip down, clean, attention to waxstat and pull down levers. Also check if your car has 2 thin rubber hoses from distributor they are both attached and in good order (as other small rubber hoses around the engine bay). I have had experience of these VW engines from 1979 to 1992. The carbs ones when set up properly go for a while. The injection ones NEVER give trouble unless someone fiddles. If the carb is not set up properly it is easy to adjust the wrong thing, and chase your tail as other settings and tolerances get thrown out.
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Just re-read your original post.
Running on (there is a anti run on valve in carb with electrical supply - but can fail or get stuck with gum)
The carb also sits on a large rubber thick gasket (like 10mm thick) and this can fail allowing huge air leaks. Suggest genuine VW unit as there are about 10 different items - ALL chasis number important.
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