B5, 1.9TDI 130bhp - White Smoke

Hi all,

I've had a number of problems with my car recently, slowly getting them fixed with help from various forums.

The car:

Passat, B5, 130 BHP 1.9 TDI. 2002 year AWX engine code.

History:

Replaced wastegate, all vacuum tubes, oil, oil filter, fuel filter, injector, injector wiring loom, glow plugs.

Problem:

When starting from cold the car chuck out a large amount fo water smoke. Smells strongly of diesel (not oil)

Vag com has the following:

17569 - Manifold Temp Sensor (G72): Open or Short to Plus
17564 - Manifold Pressure Sensor (G71): Open/Short to Ground


Could these cause a huge cloud of white smoke being produced? Is it just one unit? Can it be changed / swapped easily (locaion in car if known please)

thanks everyone

Richard

possible. White smoke is generally retarded timing or poor compression. IAT and MAP are a combined unit, yes? I'd check the wiring plug carefully.

hi thanks for the info. Now that I know where the sensor was I went and checked it. The connector was loose. Plugged it back in and the codes haven't come back (yet).

The white smoke is still an issue but only on startup from cold. I've read a few posts on retard timings - can these cause the white smoke I'm seeing?

The smoke has decreased since I changed the glow plugs and fuel filter but its still there on cold startup.

Can I check the timing? I looked at the vag com timing option but it says it doesn't work on PD engines (Is my AWX engine code a PD engine??)

thanks

Richard

If your car is equipped with an EGR cooler, it may be leaking. Coolant leaks slowly through a small fracture and builds up in the exhaust while the car is standing still and there is still pressure in the coolant system. That's why you notice the white smoke at start-up.

Glow plug relay?

Mikey2 said:

If your car is equipped with an EGR cooler, it may be leaking. Coolant leaks slowly through a small fracture and builds up in the exhaust while the car is standing still and there is still pressure in the coolant system. That's why you notice the white smoke at start-up.

Click to expand...

Thanks for the idea - didn't know about the leaking of coolant.

As a test I was wondering - if I left the cap of the coolant tank whilst teh car was stationary, so it wasn't under pressure - would that stop the leak??

The most common idea at the moment is oil leaking across the stem whilst the car is stationary. However I've put some stop smoke oil additive (they state it repairs the rubber and stops steam oil leaks by thickening the oil) - it made no difference, still loads of smoke on startup.

The garage have done another compression test and state its fine. So thats ruled out (hopefully)

Following from that I don't think that the smoke is oil related - I feel that its running rich on startup and throwing out unburnt diesel......

Anyone know of a way to test the exhust fumes to find out if it is diesel (would striking a match in the fumes be a tad dangerous ??) or whether its oil? At least then I'd have a starting place...

thanks everyone.

" As a test I was wondering - if I left the cap of the coolant tank whilst teh car was stationary, so it wasn't under pressure - would that stop the leak?? "

That could do the trick. A more tedious way would be to disconnect the coolant hoses to/from the EGR cooler and connect them directly to each other using a U-shaped piece of tube. I'd go for the test you suggested - at least it is extremely easy to perform.

White smoke is most often a sign of coolant entering the cylinder block or the exhaust system. If it was unburnt diesel, you and the whole neighborhood would smell it !

tried the car this morning afte leaving the coolant cap off all night. No difference - car started on first crank, lots of smoke and strong sickly diesel / oil smell. reved the car and it seems quite unresponsive for a good 30 secs (until the smoke went away) then it was fine.....

White smoke upon startup is glow plug related...

abctdi - you think it is glow plug related?? I've just stuck vag-com on and looked at the status - with ignition on, engine not started it shows a status of 01010000 - switching the engine on change the status to 11111111 (1 equals off)

If I'm reading that correctly only two of the plugs are on prior to startup?? Is that normal? Can I force the car to a longer pre warm time and start all 4 plugs? Just read a post about disconnecting the coolant temp sensor which defaults the glowplugs to think its colder than it is and give a 30 sec warm time - would that help??

Generally, each cylinder glow plug needs to be on for several seconds for a clean start. Check your GP fuses and relay if it has one. You can activate the GPs by not starting, but only turning the key multiple times before starting.

Hi all, think we're getting somewhere, not sure where but here's what happened tonight.....
Firstly its freezing cold tonight, temp is just above 0 degree's C. I went out and started the car - as usual lots of smoke and the sickening sweet smell, lasted for a good 30 secs whilst the car was running lumpy. After that it was fine as normal.
As a test I left it running for half an hour and then switched it off. I went back to the car after it had been standing still in the cold for 2 hours. I hooked vag com up and checked the coolant temp and fuel temp. After 2 hours in the freezing cold it showed 27.8 C for the fuel and 49 C for the coolant temp. Considering it was less than 1 C outside I thought these might be a bit high.

Now normally it takes a good 4 - 6 hours before I get the smoke reappearing on startup - however this time it smoked as thou it was the first start of the day. Again it ws gone after 30 secs or so.
I'm guessing that the temp sensor is reporting a false temp to the ecu / glowplugs - which in turns mean they are not heating up for long enough / at all so a large amount of excess unburnt diesel is thrown out the back.
Does that sound plausible / possible?? I was wondering if I disconnected the coolant temp sensor would that report back as 0 and bring the glowplugs up to max ? Can I start the engine with the sensor disconnected or would it cause all sort of problems?

thanks everyone

Coolant temp is red herring I think. I left the car overnight and went out this morning. Coolant temp / Fuel Temp / Air temp all read within 1 C of the outside temp (4.5 C)

I decided to change the pre glow period anyway - I bumped it up to 7 secs and started the car. Made no difference - still looks of smoke and the smell.

It was mentioned about hte after glow, would this still be a likely cause?

Hi did you ever got the problem sorted? I've got the same problem now...

I'd tend to agree with abctdi as to gp issue. You might want to check to make sure of the latest gp's specified for that engine and replace all of them. Most likely it calls for ngk's and perhaps a ecu reflash or in case of relay or control timer maybe that needs to be upgraded to match the plugs. The afterglow portion of the gp heating cycle is critical to the initial cold starting.

Good to know what white smoke may mean on this engine. I am used to it meaning coolant, and likely a head gasket leak. But that is on a four banger alfa gas motor.

It's true on other diesels like powerstrokes. That's where I've seen it twice, both fixed with new relays.

If you are smelling a sweet smell and puff of white smoke it is probably ingesting coolant from somewhere and burning it off. The sweet smell leads me to think this mostly, along with the white puff on start up. Can you smell a sweet smell from the exhaust after it has ran a while, even a faint wiff?

I am relatively new to VW tdi's but have been around many an engine.

Check with the other guys here too. Let us know what you find.

I've been getting this white/grey smoke too, but only near or below 0 deg. C.

It smells like diesel not coolant. I've been thinking about the possible leaks, rings, valves, seals, vacuum etc. But the glow plugs sound like a promising idea. If the engine isn't warm enough for ignition to start quickly, then un-burnt diesel could be pumped out through the exhaust (I'm theorizing here, please correct me if I'm wrong).

Now, anyone out there have good instructions on testing/diagnosing the glow plugs (if the search engine fails me)?

Thanks,
Josh