[Closed] 1.9 tdi starting problem. Could this problem be glow plugs?

Hmm.. when glow plugs fail they should stay failed - not intermittent.

There's a circuit that controls the glow plugs including a timer and a relay. The relay could be faulty. However even without glow plugs, when it coughs into life it should continue to run - especially at this time of year. The fact it died at the first roundabout is more concerninig - how far away was that? To answer your question, the glow plugs are only needed at start up, to provide enough extra heat for the combustion to start.

Where are you? If you have an engine managmenet light on I can read it for you if you're near South Wales. Oh.. wait.. the 90 in brackets means it was made in 1990?

ecu?

90bhp I think he means

90hp ?
Edit: Too slow

No,north of Scotland :O/ 90bhp,sorry.

Yeah,when glow plugs had burnt out on other cars they smoked on start-up and were a bit hesitant. This car still starts really quick with no delay. Well, most of the time :O)

It died about 400 yards from the house,Molgrips. Bit of an awkward place and luckily it wasn't too busy but it could have been a right mare. I was riding out near Kinlochewe around 8 months ago and the car was parked facing up a hill for at least 8 hours. I finished the ride and it wouldn't start so I rolled it around off the bank to get it pointing downhill and it started after a few attempts. At the time I thought the float or part of the fuel pump wasn't working quite as it should but it hasn't caused any probs since. It's a risk, I could drive it and it might not stop for many miles but when it dies when it chooses, it could get a bit scary and dangerous.

What year is the car? Mid 90s I'm guessing.

I'd have a punt on the glow plug relay, will cost a fiver or so. It sounds electrical to be honest. If the fuel pump wasn't working at full pressure you'd get loss of power all the time when driving I'd imagine. If it were an air problem you'd get low power and smoke.

Any correlation between dampness/rain and starting problems?

Definite ECU.

re: pointing up hill and not starting. You probably didn't have much fuel in the tank and so the engine pump couldn't suck the fuel up through the sender. You may have gummed up fuel sender in the tank which is fairly easy to clean or replace if your competent with this sort of thing. This engine has a fuel pump by the engine and a tube into the tank in effect, there is no pump in the tank which rarely results in fuel pressure problems.

It could also be fuel filter is gummed/blocked up. For £20 you can replace all the filters on the car. for £50 you could do plugs also.

Actually.. yes, good call.. if you were going ROUND the roundabout at the time of cutting out, it could have sucked in a load of air. Although that would result in some turning over to get it going again once on level ground.

It's 99 v reg.I was thinking electrical too but I'm one of those guessers (and don't want to be splashing out on it like I have done many years ago trying to get to the bottom of things)

It seems similar to my old peugeot when the fuel pump was on the way out. It would cut out when accelerating and you would have to wait for a short time before starting it again. It finally died about 2 mins from the garage on the way to get the pump replaced! (160mile+ drive)

I'm thinking that I might have a look around the connections and maybe give them a wee check/spray to see if anything looks a bit suss.

The only parts under the bonnet that aren't original are the battery,air filter,fuel filter,radiator and a maf? sensor so the glow plugs are doing pretty well if they are still working as they should. Battery is fine,connections are fine (had a dodgy one recently so they are all secure and the earth has a new connection to the body too)

At the time over west when it was parked for a long period there wasn't much fuel at the time but the problems starting the other day were after putting 20 quid of fuel in it. The needle is pretty high. I don't think the approach to the roundabout was the problem. I didn't make it into it so I managed to roll back to safety.

Yes, the local garage says to do the fuel filter first as it's not been done in ages (plus running veg oil approx 8 months ago!)

The use of veg oil and lack of fuel filter change sounds like the answer to it all but it brings me back to the glow plug light not illuminating and not starting.. followed by it starting perfectly as soon as you get the glow plug light showing.

I would imagine the car would still start in this weather with dodgy glow plugs unless its significantly colder in Scotland than S. England 🙂

edit: SVO or WVO will loosen deposits in your fuel tank and fuel lines and this will gum up your fuel filter. They are very cheap, if it's not the problem then you have only wasted less than a 10er.

The guy in the garage had worried in the past that if ever I drop it off for work to be done and it sits there for a week waiting for a part.. that it'll be a nightmare starting it. He has mentioned on a few occasions that it starts so well for its age after sitting there doing nowt!

<now off to collect the fuel filter.

Veg oil itself doesn't loosen tank deposits much, although biodiesel does. Did you use waste or virgin veg oil? You do need good glow plugs with veg oil as it's harder to get going.

My money's on a relay somewhere. Or cut-off solenoid perhaps.

I'm no expert but it could be the battery. I had intermittent problems starting for a while until it finally wouldnt start at all on Tuesday. Replaced battery and all is fine now.

Clogged injector/s? Try sticking a tub of STP injector cleaner through it at the next fill-up and then go and cane the tits off it.

Always fresh from the supermarket. I'm with you on something eleccy,although the filter has been on order for a week,they ordered the wrong one, so I may as week change it seeing as how it's been :::ahem::: approx 60k since the last one.

I would look at ECU or fuel issue. I have a Passat with the same engine and they are remarkably good at starting without glow plugs down to about freezing. Their is no way that dodgy glow plugs will stop an engine once it has started and driven.

It could also be an air leak into the fuel system.

Unless it is occurring regularly it is going to be very hard to correct as you will never know if you have sorted it or it just hasn't occurred for a while, I would probably just get breakdown cover and wait for it to get worse or possible never occur again.

Obviously changing a really old fuel filter is always a good idea especially if you have been running any non standard fuels.

To instantly switch between dead and perfect, it has to be electrical.

you're the expert molgrips........

Always fresh from the supermarket.

Gah... no wonder then...

As crazy as it sounds check all the air intake pipes.
My HDI was a bugger to start and i thought it was injectors/glow plugs etc.
In the end, i discovered there was a join in the intake between the MAF and the turbo. It had come apart slightly so was sucking air after the MAF.
This caused the ecu to get really confused and poor starting in cold weather. Since then it's been peachy

Also other forums suggest glow plugs don;t kick in until its -10^C

If Veg Oil is involved and the sender unit hsan't been changed or cleaned EVER then it is highly likely this is clogged. There is a small triangular check valve to stop the car from running when it rolls upside down. Well in theory at least.

You could get a fault code reader for £20 on Ebay, I think it's OBII for VAG cars. Then just google the fault code.
Engine temperature sensor is another candidate too.

greeble - Member
you're the expert molgrips........

🙂

On that eng you won't need glow plugs to start it at this time of year, may crank a little longer than normal but it will go. Get the memory checked with a diag machine, probably won't have stored any codes, if you do the diag check when it's in the non start condition you will prob not be able to communicate with the eng ecu due to no voltage supply to the ecu. Look at your fuse/relay plate there will be a relay with 109 printed on it(its the voltage supply relay for the eng ecu) the soldered joints inside this fail. 2 options here replace relay or resolder, wouldn't recommend the 3rd option of bridging the larger 2 terminals unless you know what you are doing.

Find someone local to you who has VAG-COM (try VW forum?), they'll scan it for some beer money, and you'll have a good idea what the fault is.

No point guessing when the car will give you a good indication with a code reader.

Spill of test on injectors, seen something similar on an X5, one of the injectors was stuck wide open on the spill, and was not allowing the fuel system to pressurize. The other thing it could be is fuel pressure, maybe pump on the way out.

Without futher investigation anything is just a best guess.

Veg oil expert here.
Running an older TDi on veg will pick up all the crap in the tank and send it to the filter .
Car will still run , just very badly . Most cars only need 1 filter change after 100 miles or so, some need 2. Depends on the milage of the car before you have wanged in a load of veg oil.
I would check the fuel cut solenoid as well .
On a 99 V reg this is pre PD so wont be the injectors ( hopefully )
Could be the ECU , could be the pump . Either way do not spend more than maybe £150 on getting it fixed, as you are well into write off and replace territory.

Benji this is not a CR engine with fancy tech. The injectors may not even be electronic, not sure though.

The car's not running poorly, or struggling - it's running fine then not at all. I'm telling you it's a relay or the fuel solenoid or something like that.

Running an older TDi on veg will pick up all the crap in the tank and send it to the filter .
Car will still run , just very badly

Which isn't what the OP has described..

Air flow problem in my eyes. And starting 8 times one after the other. You may as well just leave the lights on if you really wanted to flatten the battery. Oh and make sure you give it a boot full to clear the cat and such like after you coked it up by doing that

Air flow problem? That suddenly gets better on its own allowing normal driving?

Thanks for all the replies,folks. There's a few things written above that I can have a look at tomorrow while I'm fitting the fuel filter.

I asked the guy in the dealership about the possibility of the glow plugs being the problem,and also mentioned that it could still cut out during a drive. He seemed sure that it could still be causing a problem.
I'm not sure myself on that one but what I think I'll do is remove the plugs anyway to see how they've been doing for this length of time. I'll also check for corrosion of wiring in as many places as possible.

The thin flat plates in the connections of the abs pump had corroded to dust (oops, another part that failed under the bonnet!) many years ago but that had been replaced, so to guess that all wiring and pins etc are as new throughout the engine bay would be silly. I'll see what's lurking tomorrow.

Edit: when it starts, it runs like it did when I bought the car,220k ago. It's never been sluggish or spluttered. It even pulls up the hill out of town in 5th gear similar to what it was like when I got it. I'm still thinking electrical glitchiness and I have no idea where to start looking!

Thanks again,guys.

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.

UKMKIVS - Same engine as the mk4 golf, so that's the forum to be on!

http://uk-mkivs.net/forum/28-mkiv-mk4-golf-bora/

They've helped with loads of stuff with my golf...

If you're around Dorking, Surrey, I've got vagcom...

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 [i]running[/i] 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.

Cheers.