Excessive white smoke at start up for around a minute accompanied by RPM play.

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
So i got a 2003 passat, AWX engine. That is 1.9 tdi PD.
Since january whenever i start my car after in the morning (or basically happens whenever i leave my car off for over 8 hours), no matter hot or cold weather, i would get huge clouds of white smoke that smell like diesel accompanied by RPM play. This whole thing lasts for around a minute, then the smoke disappears, the RPM get stable. Then, if i switch the car off, i have to wait for another 8+ hours for this to be able to happen again. If I start it sooner there's no white smoke or RPM play. The car cranks instantly, there are no start-up problems. Also the white smoke doesnt smell like oil or antifreeze, just diesel. I went to do some diagnostics - the guy said everything seems fine. Not sure what he checked tho, but he constantly pushed the gas pedal to 4k RPM during the tests.

Any idea what might be causing that smoke?

I read it could be the injectors. But i dont see a reason why they would be dipping inside the cylinder since its a PD - there should be no pressure on the injectors once the car has been turned off. Or am i following some false logic here?

I also read it could be sucking some air into the fuel lines. Not really sure how that could impact the RPM and the smoke.
 
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CantWrite

Well-known member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.
My guess (and I am NO EXPERT)

You have a fuel drain back issue and your car slowly loses prime overnight. Does the nose of the car sit high in its normal overnight parking spot? Have you looked over your tandem pump/fuel lines all the way back to the tank for any indication of dampness? I am not sure about your car with the AWX engine code, but since you mention its a PD, do you hear the lift pump cycle when you first turn the ignition on?

How many KM's on it?
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
Around 320k kilometers or around 200k miles.
By the way i've seen it reacts differently in the morning depending on the slope. About that fuel pump - normally when i turn the ignition on i always hear the pump. The initial sound whenever i cycle it is different compared to the next ones - its always like liquid + air bubbles being moved through a hose. On any further cycles i only hear the pump working - no liquid or air moving.

Alright, i really cant figure out how this could technically happen. I've seen the fuel filter - two connected together hoses are attached to it via some plastic thingy with a hole on the bottom. As far as i know the fuel comes from one of these two hoses and goes back to the fuel tank via the other hose. If fuel is needed it gets into the fuel filter via that plastic thingy in between the hoses. Two more hoses are separately attached to the filter. One of them takes the necessary fuel for the car to run. Not sure what the other one does.
The filter is located vertically and is quite big, must be able to hold at least a liter of fuel. So if the lines between the fuel tank and the fuel filter are letting air get in it shouldn't be a problem at all i guess, since the fuel pump pushes all of that air to the filter, and since its full, back into the fuel tank.
On the other hand if the fuel line between the injector and the filter lets air in im not sure how this could be addressed. It's definitely going to suck the air into the engine.
 
Last edited:

CantWrite

Well-known member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.

Found that, hopefully it helps, makes mention how a worn tandem pump can drain back to the tank overnight.

I actually need to perform these tests as well!! I replaced my tandem pump gasket spring of 2021, but not the tandem pump as I was prolly being too cheap. If you end up replacing it, keep diesel off the coolant flange and what not below it. Prolly just best to replace while you are back there. I think it was $30-40US. (which means $130US in 2022 dollars :rolleyes:)
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
So its been a while...
I repaired my tandem pump.
Prior to the repair i used to hear bubbles in the fuel lines in the morning whenever i turned the ignition on. Since i changed the gaskets and the rubber bearing between the vacuum and the fuel side i no longer hear them. The axle got much tighter inside that rubber bearing. I noticed something called "fuel return line pressure limiting valve", its basically a piece of rubber attached to a spring which plugs a hole. I dropped a couple of drops of oil in the hole and let the gravity do its job. A couple of minutes later there was no oil left. Then i took a few cotton buds and wiped the rubber really well, put some oil again, left it for hours and it didnt drop down. So i put it together and mounted it back on the camshaft.
I was hoping that would solve the issue but nope...
The car is still shaking SOMETIMES in the morning.
I noticed a few very interesting things.
So i went on a vacation and i parked the car for 8 days straight. Then i decided to start it, it was above 30C/86F outside. Normally after this long stay it always shakes and puffs white. This time it didnt shake one bit. Not a single puff of white smoke.
I also noticed that the shake and RPM play begins around 3 to 4 seconds after i start the car (?!?!).
Since i repaired the pump ive been noticing some random moderately rapid car shakes at idle when the engine is hot, which sometimes do not show up for days, then appear multiple times during a single day.

Not losing any antifreeze. Losing a very small quantity of oil but the air hoses always have some oil in them, i guess its the turbo.

Im thinking of replacing the glow plugs, hoping to fix the startup puff and shake.
Not sure what causes the super random shake @ hot engine. Im betting its an injector.
I read it could be some valve seal. I have no idea what this is and could it cause the car to shake 3-4 seconds after i start it and cause white smoke.

Any ideas?
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
A quick update:
I think i found what the problem is.
After a lot of thinking i came to the conclusion that it cant be the injectors.
So it can be the glow plugs, but i read they are useless above 8 degrees celsius, and the car kept on smoking even when its 20 degrees outside.
So one day i decided to park the car on a slight slope facing downwards, the next morning i checked if it shaked and smoked - it did. I let the car stay there for another day. Grabbed my pc and cable on the following morning, ran VCDS and turned on the in-tank lift pump, let it run for about a minute, switched on the engine and VOILA - no smoke, no shake. Then i let the car stay there for another day, switched on the engine and bam - roughness and smoke. Repeated this whole thing once again, getting absolutely the same results.
So my conclusion is that air gets into the fuel rail. Next step would be to replace the fuel hose from the fuel filter to the tandem pump with transparent one and use it for a few weeks so i can see whats going on. If that proves to be the problem gonna buy a check valve and install it on the way between the fuel filter and tandem pump.
Will post an update after im done with these things.
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
Another quick update:
So i went to a completely different mechanic that inspected the car thoroughly. The conclusion is the O-rings on the first cylinder leak oil into the first chamber. He also said the first and the third injectors need to be given for inspection, because they have positive injection deviation quantities, the first one has 0.05, the third one is on 0.9. His advice is to drive the car as is until the deviation the third one goes over 1.2, then he's gonna open the head cover, remove the cam, the rockers and the injectors, send them and get them cleaned or repaired, then he's gonna fix the o-rings and put everything back together.
The question is: Is that oil that's being burned at startup going to harm the engine in any way, like turn into a lot of carbon? I rarely drive my car in the city, mostly driving it on highways, which might help clear things.
 

ekkoh99

Veteran Member
Joined
Oct 24, 2001
Location
Wilmette, il
TDI
2005 passat WGN TDI
I had white smoke at start up, embarrassing. I was down to 5 miles left on the tank. I did a fuel filter change and put a can of Liquid Moly diesel purge in the filter and another can in the fuel tank. drove it around for about five miles and refueled. No white smoke at start up. Still smokes with hard acceleration. will check VCDS injection quants later but overall happy its not smoking.
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
Is the smoke white or black under hard acceleration?

I posted my injector readings on my BHW in a recent thread as I also had white smoke on start up and any acceleration. New cam. I believe my issue was sitting for over 3 years, seemed to go away after driving a few miles.
 

ekkoh99

Veteran Member
Joined
Oct 24, 2001
Location
Wilmette, il
TDI
2005 passat WGN TDI
i dont know. I believe light grey. i see it at night when headlights behind me. during the day, its a light puff if i downshift and shift up again. it much better than before.
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
It's been a long time since I had a stock rune but I can put out a very noticeable black cloud (rolling coal as the redneck diesel owners call it) when I make a hard accelerated merge into the freeway. Since it's done this since the 5 speed conversion @200 thousand miles and I'm now at 280 thousand I consider this normal.
 

CantWrite

Well-known member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.
The conclusion is the O-rings on the first cylinder leak oil into the first chamber. He also said the first and the third injectors need to be given for inspection, because they have positive injection deviation quantities, the first one has 0.05, the third one is on 0.9.
The positive injector deviation numbers, are they taken when the engine is cold or warmed up? Does it matter?
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
Sorry for the delay.
So we replaced the glow plugs recently. Even tho i read they don't activate above certain temperature im amazed at the effect the new plugs had on how the engine performs. The mechanic also tuned the timing pulley, said it was very badly done. Now the car vibrates far more while idle/stationary, however, despite the fact i never noticed these vibrations, it feels smoother now while driving.
There's still a shake and a big puff of white smoke whenever i start the car in the morning that disappears when the oil gets burned off, about 20-30 seconds after start up, but i guess i'll live with it.
No idea about the deviation numbers and the conditions under which they were taken.
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
Have you by chance tried using liquid molly to treat the injectors? I bought two cans, one to do the injector treatment and one to run it the tank..
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
The mechanic used something to treat them but he said the injectors are just going bad and it cannot be undone. Other than that i've used Fuchs' Maintain diesel effect. But the problem overall is not the injectors going bad, its the O-rings around them. The injectors' deviation is within spec.
 

CantWrite

Well-known member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.
Some of my own observations.....

Back story, last winter my car always started rough on cold morning with white smoke/air intrusion. This summer rock fall came down next to me while driving and 2 rocks rolled under the passenger side (Right-Hand Side in USA) and one of my lines slowly seeps.

Car sat for 14 days nose down. Went to start it (cycled GP's 3 times and heard gurgles from LP each time, 1/2 tank of fuel) and fired up without any air intrusion or white smoke, I was surprised.

By chance do you have a coolant heater? I installed a frost heater 3 weeks ago, been +/-10F here for my morning start-up/commute. With the nose down, the Frostheater runs on a timer for each morning and the car fires instantly without roughness/white smoke/ air intrusion.

While I am currently in a "bandaid" situation, the coolant heater has made a world of difference. Which leads me to believe I may have air intrusion in a different area then I think....which is why I am very interested in your thread and hope I am not muddying it up too bad.

How do you know oil is getting into your cylinders? Does it burn blue on start-up? Have you replace the FF > TP line with a transparent one?
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
Interesting.
I dont have a transparent line between the filter and the tandem pump, but i put a check valve. Technically there should be no way for it to leak air.
Considering how the fuel lines work 3 key cycles should push the air out, yet it still blows white smoke whenever i do this..
 

CantWrite

Well-known member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.
Leaving work yesterday, My car was level, or just a titch nose up (not enough to roll backward). 28-30F; Not plugged in, one GP cycle, and when it fired.....cloud of white smoke, definite air intrusion, I stepped on the fuel peddle and brought it up to 1200 rpm and worked the air out. Smoothed out in 10-15 seconds.

What your thread is having me question about my own car is.......why does warming the engine prior to firing it, either through mechanical means or outdoor temperature, keep air intrusion out of the initial start-up......? Does the engine warmth, mechanical or temperature, expand something internal to the engine that take air out of the initial start-up...?

I have more questions than answers. I do know I have a similar issue to you prior to the rock fall hitting the RH Side of my car.
 

Constantin

Member
Joined
Sep 1, 2020
Location
Bulgaria
TDI
2002 AWX 1.9 130 hp
Well from what ive read on the internet many things can cause this, the most probable one being the tandem pump.
As i wrote earlier i had air bubbles with every flip of the key after 8+ hours of the car being parked. I just heard them...after opened the pump and replaced the seals the bubbles disappeared. Im almost certain i was able to hear these air bubbles before the current issue appeared.
The next cause seems to be the O-rings leaking a veeeery tiny amount of engine oil into the cylinders.
The last cause if found is the valve seals leaking fuel into the cylinders. Again - a very small amount.
So, i guess, when i fire up the engine it starts heating real fast, but because that oil is on the bottom of the cylinder and moves up and down with the piston it takes considerably more time to start burning, compared to the engine fuel that starts burning right off. That explains why in my case it starts shaking the car and blows white smoke about 3-4-5 seconds after i fire up the engine.
My mechanic said the valve seals very rarely go that bad, and since its not the tandem pump whats left is the O-rings.
 

CantWrite

Well-known member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.
Thank you very much for the information. I did replace my tandem pump gasket, but did not open it up or replace anything further.

I think my first order of business is to fix/replace my fuel lines along the bottom of my car where the rock fall rolled under it.

You might have answered it, and I am just too blind to recognize, but what's your theory on why pre-heating the engine with a coolant heater (frost heater in my case) cause the engine to start normally without white smoke? Is the cylinder with that little bit of oil, getting warm enough to burn the oil? Or maybe its warming the TP enough that its "leaks" are closing shut. Or a combination of?
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
If you don't want to spend the 300 or more on a trial and error tandem pump swap, I've had good luck with the 150 eBay ones.
 
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