My 1994 1.0 Polo coupe (the very last of the old model with fuel injection) has the irritating and dangerous fault of losing power for no apparent reason. The car can go for hundreds of miles without fault, and then on one journey, go dead usually at low revs. However, last week on one evening it cut at 30mph, was reluctant to restart, started five mins later and would then cut within 20 feet. When driven to the garage the following morning, it ran fine! Intermittent faults are the worst - 2 good mechanics have been stumped on this one. Any suggestions as to what this could be would be greatly appreciated. The car has a brand new distributor & battery, and on a friends advice, I changed the fuel relay. Otherwise, it is in great nick and is well serviced.
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As you already have a new distributor,I'd suggest renewing the coil amplifier unit,if not already done.Another possible fault area is the rather exposed fuel pump fuse on LH bulkhead,you can find corrosion/bad contact here which sometimes causes cutting out.
P.S.If the distributor you've fitted is not a genuine item this could again be the problem.OE distributors are now very reasonably priced at around £70.
David Davies (Tune-Up Raglan)
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Thanks guys. The more research I do on this subject the more distant a cure seems to be - it appears that VW's are plagued by 'cutting out' problems, from 80s cars to brand new ones. Suggested faults include electical, fuel, and a new one for me - a corroded fuel filler causing flakes ion the tank and then in the fuel line. See: www.parkers.co.uk/advice/message_board/topic.asp?T...5
for an endless list of similar problems. I can't get any joy from my usual VW specialist (they 'need to see "it" happen - fair enough but it cannot be relied upon to perform on cue)
David - the distributor is by bosch if that helps. I'll check your points but fear I can only take it to the VW franchise, and perhaps get some help courtesy of the ECU gadgets they have. I'm reluctant to sell when I've spent money on servicing, timing belt etc that I won't get back, but at the same time I don't want to replace lots of parts on the off chance they may be the cure, to no avail (like most peoples experience in the parkers forum), or worse, experience the problem on the motorway or when crossing a dual carrigeway.
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Chris,
I suffered exactly the same problem with an 83 Cavalier. I decided the sender in the distributor was faulty, so replaced the whole unit with one from a local breaker. That cured it.
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If it completely dies when the problem occurs (no roughness etc.) then is is likely to be an electrical problem. As it's a VW I would go straight to the Hall Sender as No1 culprit. A well known problem.
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Although my experience was with a completly different car, I did find going to a competent independent tester of enormous value. Can someone recommend a mobile diagnostician of electronic/fuel injection systems in your area?
I found that even though like yours the fault (non-starting) was irritatingly infrequent, there were nonetheles specific faults showing up even when apparently running normally.
In my case he spotted a poor output from the ignition amplifier module (and tested a spare secondhand one for nothing), confirmed that the crankshaft position sensor was OK, and highlighted abnormally high resistance in the HT circuit, not the coil.
The test cost £50 and he gave me the spare module free. All I bought was a new distributor cap, rotor arm, leads and plugs.
Before testing I had been about to embark on a depressing round of buying things just to see if they solved the problem.
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sounds like ignition but can't be sure.
next time it cuts out check for fuel in the fuel filter and check for a spark by removing a plug, grounding it and turning the engine over.
I would get a TCI amplifier module from a scrapper and see if it still cuts out with this one fitted. Hall sender is also a possible culprit
when ny golf had ignition problems I bought an entire ignition system for 20 quid and replaced it bit by bit until I found it was the loom connecting it all together
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and check for a spark by removing a plug, grounding
it and turning the engine over.
The books always say that. It's much easier just to use an old plug!
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absolutely, unfortunately that requires common sense
;-)
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Despite the new (Bosch) distruibutor, the ECU was showing a hall sender fault which wouldn\'t clear, so on my mechanics advice I changed the distributor yet again to an OE part. This hasn\'t stopped the car cutting out intermittently, leading to frustration and a waste of a hundred quid! ECU still registers a hs fault (won\'t clear), so hope to get one from the scrapper to try that (I understand I need an identical code to the current unit?) Same goes for the coil, which seems to vary between years even on the MK3. If neither work, | think theres nothing else for it than to fling it.
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If you look at the plug connnecting to the distributor you will see that it has three wires marked -/- o -.Try connecting the negative (-) wire direct to earth.Also double check the earth wires from battery negative to the engine block,adding an extra cable to ensure good continuity.This mod. did cure a cutting out problem on a Polo similar to yours.Please keep us updated on your progress
PS The plus sign cannnot be correctly displayed,not sure why.
David Davies (Tune-Up Raglan)
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Hi, This sounds like a fuel pump problem to me. Firstly what makes you think it is an ignition problem. When it won’t start have you established there is not a spark, i.e. pull a lead and temporarily fit a spare plug and check for a spark.
If you sit quietly in the car and turn the ignition on you can hear the pump whine for 2 or 3 seconds. So next time it cuts out listen for the turn on whine, if no whine then here is your problem. Regards Peter
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Many thanks to all who have taken the time to help. Fuel pump sound is audible at startup and the noise remains, as I believe it should. It there also when it won't start, usually after it cuts out (this resolves itself if its given a min'). The car is now in the hands of an auto electrician, who after providing graphs and charts on the poor performance of the coil, identified this as a good bet. However, two new coils have been rejected as faulty, and hopefully a decent one will be delivered tomorrow. Of more alarm, the ignition leads were blue with corrosion, and as the car was recently serviced and later presented with this fault to the VW specialist, is perhaps unforgivable. Also, this garage pointed out the ECU hall sensor fault which would not clear. The elec' says this is perfectly normal when the ignition is on, and the fault clears, as expected when the engine is started. It now appears the 2 distributors were a dead loss. Anyway, before I approach the VW spec' ( I can't honestly believe that he was unaware of how the ECU reading worked, but what about something as basic as the leads?) with a few polite but direct questions, I'd rather be confident that the coil & leads & new earth strap cures the fault, and that I have my facts right.
Chris.
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