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Discussion Starter · #1 ·
BORA TDI 110 (2001) 98000 miles

Basically when starting the car after its been stood either 9 hours or as little as 5 hours, i get alot of blue smoke and the engine sounds really lumpy and underpowered. After a few seconds off pulling off my drive it goes and the car just sounds like a normal tank.

But its the amount of blue smoke and lumpy running thats worrying me. Plus i get funny looks when the car is giving out a massive blue cloud. Its gradually got worst as the weather is getting colder. only owned the car for 6 months.

Also noticed when i turn the key and wait for the glow plug light to go out, the car doesnt always start on first turn over. normally second time it starts. Ive noticed this at diffferent times of day but mainly when cold.

anyone have any suggestions, not sounding rude but i dont want the reply of " its normal" this def isnt normal :) a bit of smoke yeah but not amount im getting. Could it be glow plugs? sorry for long post...
 

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I'd say you are getting air in the fuel system.

It's the most common problem on a diesel for bad starting.

What's happening (I'd suggest) is that the car is self bleeding the fuel system which will cause the lumpy running etc.

This also explains why it goes away after a few seconds.

Check for air leaks into the fuel system, especially around the fuel filter, in fact it may be as well to change the fuel filter.
 

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Discussion Starter · #3 ·
thanks for quick responce.I recently changed my fuel filter as i thought that may be problem, but its exactly the same. Could it be the MAF? or does this not effect anything to do with starting?
 

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I would double check the fuel lines and filter connections before you consider the maf.

Also on the 110's (90's) as well, on Nr3 cylinder, the injector has a lift sensor which can cause bad running.

A good idea would be to find someone on here who will read the car for faults.
 

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Discussion Starter · #5 ·
I would double check the fuel lines and filter connections before you consider the maf.

Also on the 110's (90's) as well, on Nr3 cylinder, the injector has a lift sensor which can cause bad running.

A good idea would be to find someone on here who will read the car for faults.
im thinking of buying a vagcom cable myself as already got software. Can you extend a bit on what ya mean about lift sensor? im not a mecanic but dont think it will be the fuel lines. surely i would see leaks on drive etc?
 

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I'm not 100% sure what it does but it is a needle lift sensor that provides an input to the ecu. I would imagine it is a measurement of the injection duration.

Also, you are very unlikely to see fuel leaks. Air ingress is exactly that are very hard to spot. Look at at the fuel lines / leak off pipes and maybe remove and re-seat them.
 

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Needle lift sensors, MAFs? Easy Tiger!

I had the exact same problem ith my TDI when I first bought it a few years back. I'm guessing that it's ONLY cold starts that do this, ie, restart it an hour later and it's fine?

First things first - Glowplugs. Buy a set and fit them (under ?20). It's pretty likely that with the car at this age it'll need a new set, especially with the cold mornings now. Check the wiring loom at the plugs too, make sure it looks in good nick - it carries a lot of current.

Come back to me once you've tried that.
 

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Sorry ct.p, I second the glow plug theory.

Same thing happened to my old Vauxhall diesel van and a new set of glowplugs sorted that out.
 

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Discussion Starter · #9 ·
thanks for the reply, suppose it wouldnt hurt changing the glow plugs. i guess this is a simple job to do. do u need any special tools?
 

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Discussion Starter · #11 ·
changing the glow plugs - is this solving the starting problems or the blue smoke on start up or both :)

cheers for help guys
 

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I thought blue smoke indicated the burning of oil. Ive only seen thick white smoke caused by "inactive" glow plugs...the unburnt diesel
 

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Discussion Starter · #13 ·
its weird this blue smoke on start up problem with tdis, its a common problem but no one seems to have a solution or a fix if u get me, its a mystery :)

surely someone has been to a stealer with this problem? what was the resolution
 

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OK, since there's some demand on here, there's more.

NOTE - Change your glowplugs first! It's almost certain to sort out poor cold starts.

There's a few things that can cause excessive smoke on startup, but the main cause is unburnt diesel. How that happens can be down to a few factors,

1) Poor glowplugs failing to adequately heat the combustion chamber. They don't have to be dead to cause problems, glowplugs' performance tails off as they age. A new set is a cheap and easy part to swap, and see if matters improve.

2) The basic engine or injection timing may be out. This may give poor starting, low output power, excessive smoke, fuel consumption problems, etc., etc. To a certain extent, the self-correcting nature of the injection pumps on modern diesels can overcome this, but you can get symptoms at startup, especially when the engine is stone cold.

3) Injector wear. If the spray pattern is out, or the injectors are leaking down when the engine is switched off, the engine will be more difficult to start, as the low speed of cranking makes the proper atomisation of the fuel even more critical than usual. It might be worth having a diesel specialist check the injector's spray pattern and opening pressure, and also check for leaks from the injector nozzle.

4) Major engine wear. Lack of compression = poor starting. Very unlikely in a 100k TDI, unless you've replaced the engine oil with gravel and marmite.

I'm fairly willing to bet it will be glowplugs, and *maybe* a slight timing correction if it's still not right after that.

Oh, and if your TDI seems to crank just a little too long before catching but is otherwise fine, try changing the temperature sender, it improved mine when I changed it recently.
 

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Needle lift sensors, MAFs? Easy Tiger!

I had the exact same problem ith my TDI when I first bought it a few years back. I'm guessing that it's ONLY cold starts that do this, ie, restart it an hour later and it's fine?

First things first - Glowplugs. Buy a set and fit them (under ?20). It's pretty likely that with the car at this age it'll need a new set, especially with the cold mornings now. Check the wiring loom at the plugs too, make sure it looks in good nick - it carries a lot of current.

Come back to me once you've tried that.
Quite supprisingly, a TDI hardly uses it's glowplugs in our climate, but....

I suppose it wouldn't hurt to change them.

My money however is still on an air leak.
 

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Discussion Starter · #16 ·
OK, since there's some demand on here, there's more.

NOTE - Change your glowplugs first! It's almost certain to sort out poor cold starts.

There's a few things that can cause excessive smoke on startup, but the main cause is unburnt diesel. How that happens can be down to a few factors,

1) Poor glowplugs failing to adequately heat the combustion chamber. They don't have to be dead to cause problems, glowplugs' performance tails off as they age. A new set is a cheap and easy part to swap, and see if matters improve.

2) The basic engine or injection timing may be out. This may give poor starting, low output power, excessive smoke, fuel consumption problems, etc., etc. To a certain extent, the self-correcting nature of the injection pumps on modern diesels can overcome this, but you can get symptoms at startup, especially when the engine is stone cold.

3) Injector wear. If the spray pattern is out, or the injectors are leaking down when the engine is switched off, the engine will be more difficult to start, as the low speed of cranking makes the proper atomisation of the fuel even more critical than usual. It might be worth having a diesel specialist check the injector's spray pattern and opening pressure, and also check for leaks from the injector nozzle.

4) Major engine wear. Lack of compression = poor starting. Very unlikely in a 100k TDI, unless you've replaced the engine oil with gravel and marmite.

I'm fairly willing to bet it will be glowplugs, and *maybe* a slight timing correction if it's still not right after that.

Oh, and if your TDI seems to crank just a little too long before catching but is otherwise fine, try changing the temperature sender, it improved mine when I changed it recently.
wow great help :) sounds to me like glow plugs and timing. Is it expensive to get timing re-done/adjusted, is it something i could do?
 

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I have been told my temp sensor needs changing due to bad warm starting ( sorry for derailing thread :( )

Can anyone tell me where the temp sensor as Im gonna change this first before anything else... I suppose I will change the glow plugs as well while im at it :)
 

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Discussion Starter · #19 ·
yeah im going to change glowplugs and temp sensor at same time. Anyone know of any guides or rough prices. Nest thing will be the Maf. Is it true that if u unplug the maf and the car runs better then the maf is faulty. (what im trying to say is by unplugging the maf is this this good way of diagnosing faulty mafs if u get me)
 

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Changing glowplugs is easy - get a long reach socket and unscrew them.

Changing temperature sender is easy. Slide out a clip, pull, shove new one in. It's at the gearbox side of the engine on the AHF motor. Do the job with the engine cold, and if you're quick you only lose a drop. (you won't even need to top up) Make sure you get the right type from the dealer - there are two different connectors.

Engine timing. Special tools required. You need the same setting tools used when changing the cambelt, and a VAGCOM or VAG diagnostic tool to set the injection pump timing. You can do this with alternatives - 5mm aluminium angle is a perfect replacement for the camshaft setting plate, and the injection pump setting pin can be copied using a suitably sized drill bit (about 5.5mm IIRC) or some of the cheaper timing sets have a pin that fits.

MAF - I *really* don't think this is the problem. The classic symptom is a general flatness in the 2-3000 rpm area which would occur at all times, not lumpy starting and rough running for a few seconds.
 
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