Check the glow plug relay, also there are a set of big fuses in a box just by the battery on a mk4 which sometimes corrode and give this kind of issue.
http://uk-mkivs.net/forums/ is your friend in these matters
Just to eliminate the glow plugs disconnect the power feed from them and test the resistance of each plug.
Infinite resistance = broken.
If the engines conking out and not restarting i very much doubt its anything to do with the glow plugs. Needs plugging into vag com id be expecting to see a temp sensor prob or more likely a crank position sensor fault. Fuel filter etc is worth doing as people have said its cheap and easy.
Worst case its a ecu problem i know they like to die on petrol golfs of that age and its pretty much ready for the scrap heap if it does.
What would a bad temperature sensor do?
Check the glow plug relay.
Temp sensor are often linked into the fueling and cold start equipment like glow plugs and excess fuel for cold starting. Wouldnt expect the random cutting out from one tho. If all is well on the fuel side of life get it plugged in see if anything comes up before starting down the change this change that route.
This is a diesel remember, so there's no mixture issues.
My money's on the cut-off solenoid, or its wiring. It might even just be not plugged in properly.
This is a diesel remember, so there's no mixture issues
Could you explain this one?
molgrips the expert
If a petrol engine thinks it's hot when it's cold, it'll put less fuel in and then the mixture won't ignite from the spark, cos it'll be too lean.
Diesels don't work that way, they only ever inject fuel into hot air which will always burn if the air's hot enough. Which it will be unless a) it's very cold and the glow plugs aren't working or b) the engine doesn't have enough compression ie is a bit knackered and worn out.
That's not quite right molgrips. On modern diesel engines, the temp sensor forms a closed loop which helps the ECU decide how much fuel to inject. So duff sensors can upset starting. When the engine is warm, the glow plugs can still be used for emission management.
It is right in the sense of their being no air/fuel mixture like in a petrol, so the fuel always burns given sufficient heat. But yes if there's not enough fuel to turn the engine over, then it won't start or run well.
But they also have a feedback look with the engine speed so that if there's not enough fuel to maintain idle they'll just add more - won't they?
Still won't produce the OP's symptoms though!
Anyway, OP- you don't need partly-informed forumites like us, you need a garage and Vag-Com, and it sounds like you're doing that. So good luck, and let us know how it goes.
So the filter has now been replaced, bled it and its up and running again. Took it for a drive and as expected,it's running fine. I have unclipped about 6 connections around the engine bay, including one that is linked to the lead running to the glow plugs, and checked/sprayed them with acf50 along with the three fuses in the plate above the battery. The bigger fusebox/relay box? is under the dash so I've pulled out a few of them but could do with checking them as nothing appears wrong with any of them. (is No 106 the glow plug relay?) Should I pull each of them out and check them with a multimeter?
I might just run it next week and see how it goes. What I have found out is to turn it over and over (only enough to illuminate the dash without trying to start it) if it fails out on a drive until the glow plug light appears on the dash. If it does, I can go full turn with the key and start it. If it doesn't illuminate,and I keep trying to start it, it drains the battery. Finding this out enables me to keep 1/4 turning the key without actually wasting the battery so who knows.. I might get away with that.
1) Find out what engine you have. It's either 1Z or AHU I think, google for pictures of each and see which it looks like
2) Find the fuel cut-off solenoid (It is likely to be inside the injector pump, look for a plug that goes into that)
3) Check the wires for obvious damage and check the connector's plugged in. If it's not starting, put a multimeter on that connector and see if it shows a voltage when you're trying to start (with an assistant, probably).
I think that the glow plug indicator has various functions, alerting you to problems - not just the glow plugs, but I could be wrong.
When my old Diesel Polo did something like this I spent ages cleaning and checking all the earth connections.. Turned out in the end it was the positive battery connector full of corrosion. It would run all the aux electricals fine, but wouldn't give enough current to drive the glow plugs and starter.
Sorry for bumping this old thread.
But i am facing the exact same problems as martinxyz. So i would really appreciate if you would share your knowledge of the cause of the problem ,assuming that you got it identified and fixed
Get the codes read, could be a crank position sensor (if it has one) they can fail intermitantly. You won't be able to guess.
Had similar issue on my VAG, turned out to be the fuel tank pump (no codes came up on diag). Even though it was an 'electrical' issue , it was intermittent for several weeks, even after failing completely & being towed to a garage, it started working again.. then 'luckily' failed whilst they worked on it.
Theres a couple of good basic ideas to check there. The first that stands out is Bigsurfer's suggestion air is getting into the fuel system.
I had a second hand Bora 115bhp tdi for 3 months before EXACTLY the same thing. Would cut out mid flow, take loads of attempts to get going and then just start perfectly. It would then cut out and wouldnt start again. If it was on the flat, generally fine. I replaced the relay that Markrtw mentioned at the start of the 2nd page and it did nothing. Turns out it was a fuel pipe that had come loose to the fuel filter and at points was sucking in enough air to conk out. When I was cranking it and cranking it it was pushing the air through to a point fuel would be pumping enough diesel through but when there was too much demand on the engine it would suck in air again.
Its a basic check, just find the fuel filter which will be on the left if you are looking at the front of the car and check if its leaking diesel.
If its not this I doubt glow plugs would stop it running which is why I would attribute it to air/fuel mixture and a sensor rather glow plugs. A fault code reader is worth its weight in gold, somewhere like GSF (german swedish french) will sell one for around £20 which will be OBDII compatible.
I just had a mechanic to look at my car. He had a fault code reader connected today, and could not contact the ECU. Turned out that my problem was a defect relay that was supposed to power up the ECU.
He also said that the glow plug lamp was also used to indicate problems with the ECU - hence the weird behaviour of the glow plug lamp.
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