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Experiencing Heavy Smoke in Cold Weather from Soothing Blue 1.9 TDI Golf 4, Engine 90 km ALH

Alansi007 16761 19
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Why does a 1.9 TDI ALH smoke heavily blue/white and start badly when cold?

A heavily smoking cold start on this 1.9 TDI should be checked first for injection timing, glow plug power, compression, and injector overflow, not replaced with a pump right away [#16968104] In one similar case, the injection angle was found extremely advanced at 70 and after setting it to the proper 42–48 range the engine ran much better; the fuel dose was also corrected to about 3.0–3.2 [#16975812] That same case also had no power on the glow plug strip because of a bad fuse/connection, and fixing it restored current to the plugs, which can directly cause hard starting and smoke if one cylinder does not heat [#16975812][#16989405] If the problem remains, check the fuel temperature sensor in the injection pump, because it was suggested as another possible cause of similar symptoms [#16989172]
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  • #1 16968083
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    Hello . I have a problem from somebody
    Time with my golf 4 engine 90 km ALH. It smokes very hard when it's cold, I have to hold on the starter for some time, and if it catches a swirl of blue smoke, and then white. I would check the injection angle, the amount of fuel, the glow plugs, and everything in the best order. The diagnostician recommended me to replace the injection pump, but I want to advise someone who had a similar problem.

    HELPPP !!!
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  • #2 16968104
    robokop
    VIP Meritorious for electroda.pl  
    Posts: 29406
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    Please enter in order:
    - compression pressure value,
    - injector overflow test result,
    - value of current consumed by glow plugs during cold start.
  • #3 16970233
    mate1000
    Level 2  
    Posts: 2
    Rate: 6
    Hello, I have the same problem only that the Audi 1.9 TDI 90 km pump I had sealed and regulated and the problem is still ... I noticed that not only on the cold only as it stands so with 3 hours it already has a problem. After a night stop, as long as he turns and starts up, all you have to do is put it out and I start it again without a problem, so I think that something with fuel, that he runs away somewhere for a long time ...
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  • #4 16971141
    migmig85
    Level 26  
    Posts: 722
    Help: 85
    Rate: 332
    mate1000 wrote:
    Hello, I have the same problem only that the Audi 1.9 TDI 90 km pump I had sealed and regulated and the problem is still ... I noticed that not only on the cold only as it stands so with 3 hours it already has a problem. After a night stop, as long as he turns and starts up, all you have to do is put it out and I start it again without a problem, so I think that something with fuel, that he runs away somewhere for a long time ...

    This is how it looks like the fuel is coming back.
    Take the test, plug the fuel in the bottle, light up a bit, let it go out and turn off in the morning and see if it fires the shot.
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  • #5 16972302
    mate1000
    Level 2  
    Posts: 2
    Rate: 6
    All in all, I put a transparent tube on the pump's supply cord to see if any blisters are being made. If it goes back, this bottle probably won't do anything ... But can I try connecting it to the pump?
  • #6 16975812
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    migmig85 wrote:
    mate1000 wrote:
    Hello, I have the same problem only that the Audi 1.9 TDI 90 km pump I had sealed and regulated and the problem is still ... I noticed that not only on the cold only as it stands so with 3 hours it already has a problem. After a night stop, as long as he turns and starts up, all you have to do is put it out and I start it again without a problem, so I think that something with fuel, that he runs away somewhere for a long time ...

    This is how it looks like the fuel is coming back.
    Take the test, plug the fuel in the bottle, light up a bit, let it go out and turn off in the morning and see if it fires the shot.


    Yes, only today at my friend's, he connected his computer, and so:
    Injection angle I had very high, as much as 70, changed me to optimal, i.e. jumps 42-48
    The fuel dose is at 3.0-3.2 (it's perfect because it was 1.0, he had a little bit bigger kick, but he jerked in gears like a possessed person, now nothing!) ;)
    We checked the fuse and glow plug strip with a meter, and it turned out that there was no electricity ?? (I paid the mechanic to check me professionally and said that "it is perfect), we changed the fuses, and the current goes to the strip.
    And now yes. At kata 42-48 it is difficult to smoke even when warm, but it should be like that.
    (I add that the fuel does not go back because we checked)
  • #7 16988946
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    Gentlemen, save me! Maybe someone had something similar ??? !!

    ??
  • #8 16989172
    migmig85
    Level 26  
    Posts: 722
    Help: 85
    Rate: 332
    And the fuel temperature sensor in the injection pump ??
    I used to have such a case.
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  • #9 16989211
    krzych1-b
    Level 21  
    Posts: 829
    Help: 17
    Rate: 215
    Gentlemen, I found something like this.
    Black smoke - unburned fuel (e.g. pouring injections)
    Blue smoke - oil in the combustion chamber
    White smoke - water in the combustion chamber, in other words the gasket released under the head EPA.
    All you need is a small leak and you can change the half motor :D .
    Maybe try to go this way?
  • #10 16989272
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    krzych1-b wrote:
    Gentlemen, I found something like this.
    Black smoke - unburned fuel (e.g. pouring injections)
    Blue smoke - oil in the combustion chamber
    White smoke - water in the combustion chamber, in other words the gasket released under the head EPA.
    All you need is a small leak and you can change the half motor :D .
    Maybe try to go this way?


    Gasket never, I have a new one because I replaced pistons a month ago ??
  • #11 16989405
    krzych1-b
    Level 21  
    Posts: 829
    Help: 17
    Rate: 215
    I would still look into the timing setting, if everything is set to tip-top, because something does not suit me with these fumes. I used to have a valve in the volvo supported and a turned down shell on the crankshaft - but you would hear a knock and a cloud of smoke behind you
    One more question . Did you check the candles individually, i.e. dialed and plugged into the charger, for example, and when do they heat up?
    Just that one of the candles is already finished (or finished) and then it starts to catch the temperature, then you have trouble starting the engine and there is smoking (unburned fuel).
  • #12 16991188
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    With this timing, I have it perfectly set, because I would hear that something is wrong. With candles there is such a miss that I had a burned candle fuse, it is replaced with a new one, but the strip that gives the current to the candles, at the last candle is broken, and does not reach the candle. This may be the reason. I will add that at start-up after a night, and possibly after 4 hours of awful awfulness to Niebeisko
  • #13 16992129
    krzych1-b
    Level 21  
    Posts: 829
    Help: 17
    Rate: 215
    If there is no connection with the last candle then you need to fix it, at least you will eliminate the next fault.

    I will return to the color of smoking.
    Leaking or faulty valve seals cause oil to drip into the engine from the valve stems and hence the smoking !!!
    - Turbocharger failure or oil suction via pneumothorax (it can be replaced cheaply), unfortunately turbo repair is more expensive. With a damaged turbo you have a decrease in power, which can be felt immediately after the appearance of smoke.
    - engine idling means cylinders {but as you replaced pistons, you also honed and honed cylinders}
    - air filter, it happens that its contamination causes the emission of blue smoke. In old cars, this means high engine wear. But here you probably have clean.
  • #14 16993112
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    * The strip on days will be replaced

    * turbo is ok It pulls up nice, there is no loss of power or anything related to it

    * pistons were replaced, the whole head checked, new gasket, also in this direction I would not go.

    * As for the air filter. It was replaced a year ago, I checked some time ago and is a bit dirty, there is no tragedy, but after a year it is time to pass, but I think that this is not the reason for such "VERY" heavy firing.
  • #15 16993320
    krzych1-b
    Level 21  
    Posts: 829
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    Pistons made or rings you have new, but I also meant cylinders. Made-Yes? If so, the compression is -hmm :?:
    Did you reach valves or were they just checked for leaks?
    Sorry to ask, but I'm starting to run out of reasons for this smoking.
  • #16 16993393
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    Pistons and rings new, so it's ok, compression is, it would be smoking from the bayonet

    The valves were not checked and not run in
  • #17 16993512
    krzych1-b
    Level 21  
    Posts: 829
    Help: 17
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    I have a request, answer all questions or suggestions because I am crazy. Have you looked at emphysema?
    And the fact that it burns heavily, it is the fault of the unplugged candle - they need to heat four and fire into four cylinders, because despite the fact that the engine fires in three, HE burns only in these three cylinders - no and telepiece engine. in cold weather, like good compression, the engine will start without a problem.

    Added after 40 [minutes]:

    And one more thing because I forgot to write - very important. Replacing rings and pistons, without sanding or honing the cylinders, only makes matters worse.
    How many kilometers do you actually have on the meter?
  • #18 16993633
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    Odma is fine, it was checked, and as for the cut, the head was not ground, because it was already sanded twice (from the previous owner), so the mechanic give a larger seal.

    220,000 are driven, but I dare say it was distorted ??
  • #19 16993654
    krzych1-b
    Level 21  
    Posts: 829
    Help: 17
    Rate: 215
    I don't think you have a cracked head somewhere near the oil channel (darkest scenario)
    If he is a friendly mechanic, he should do the renovation well, my suggestion is this: I bet on the leakage of valves (valve stems). He did not exchange for new sealants.
    And take to heart what you got at PW from me
  • #20 16993940
    Alansi007
    Level 7  
    Posts: 9
    Rate: 10
    I also don't think it's the reason for a broken head. It was tested and I have known the mechanics for quite a long time. I will check these valves in a week, maybe that's where the problem lies
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Topic summary

✨ The discussion revolves around a 1.9 TDI Golf 4 (ALH engine) experiencing heavy blue and white smoke during cold starts. The original poster has checked the injection angle, fuel amount, and glow plugs, but the issue persists. Responses suggest various diagnostic approaches, including checking compression pressure, injector overflow, and the fuel temperature sensor. Some users report similar issues with their Audi 1.9 TDI engines, indicating potential fuel leaks or problems with the injection pump. Others mention the importance of checking valve seals, turbocharger condition, and the air filter. The poster has replaced pistons and gaskets but has not checked the valves, which may be a source of the problem. The discussion emphasizes the need for thorough diagnostics to identify the root cause of the smoke.
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FAQ

TL;DR: Cold-start blue/white smoke on 1.9 TDI ALH often traces to injection timing, glow-plug power, or fuel drain-back; one case improved after correcting timing from “injection angle … 70” to 42–48 and fixing glow-power supply. “Injection angle … 70.” [Elektroda, Alansi007, post #16975812] Why it matters: This FAQ helps Golf 4/Audi 1.9 TDI owners diagnose hard cold starts and heavy smoke fast.

Quick Facts

What do blue vs. white vs. black exhaust smoke mean on a cold-starting 1.9 TDI?

Use color to aim diagnosis. Blue means oil burning, often from valve seals or turbo oil ingress. White means coolant/steam entering combustion, such as a head-gasket path. Black means over-fueling or poor combustion. Fix the root system before replacing major parts. [Elektroda, krzych1-b, post #16989211]

How do I check for diesel fuel drain-back overnight?

Do a quick bottle test. 1) Run the feed and return from the pump into a clean bottle. 2) Start, let it run briefly, then shut down for the night. 3) If it fires instantly in the morning, investigate line leaks, check valves, and filter head seals. “This is how it looks like the fuel is coming back.” [Elektroda, migmig85, post #16971141]

Which baseline measurements should I capture first?

Record three numbers: cylinder compression (consistency across cylinders matters), injector leak-back volume (identifies nozzle wear), and total glow-plug current draw during cold crank (confirms actual heating). These three values steer accurate next steps and avoid guesswork. [Elektroda, robokop, post #16968104]

What timing and fuel-dose figures helped a similar ALH case?

One owner corrected an excessively advanced timing (“injection angle … 70”) to ~42–48 and set injection quantity near 3.0–3.2 mg/str. That change eliminated surging and improved drivability, though starting still needed proper glow support. Numbers guide, not replace, mechanical checks. [Elektroda, Alansi007, post #16975812]

Can glow-plug power delivery faults really cause heavy blue smoke?

Yes. A blown glow fuse or cracked bus bar can leave plugs unheated, leading to poor cold combustion and blue smoke. Repair the fuse and bus bar continuity end-to-end before deeper engine work. Owners reported no power at the rail until fuses were replaced. [Elektroda, Alansi007, post #16991188]

My car starts after an overnight crank but struggles again after 3 hours—why?

That pattern often indicates partial fuel drain-back or air ingress. After a short soak (around 3 hours), residual heat is gone and suction-side leaks show up again, extending crank time. Verify with a transparent line or the bottle test and correct line seals. [Elektroda, mate1000, post #16970233]

Could a faulty fuel temperature sensor in the VP pump cause hard cold starts?

Yes. An incorrect fuel temperature input skews the pump’s timing and fueling during start, worsening cold behavior. If timing and glow circuits check out, read the sensor live data and compare when cold. Replace the sensor if readings are implausible. [Elektroda, migmig85, post #16989172]

Do valve stem seals or a cracked head explain persistent blue smoke?

Leaking valve stem seals allow oil into the intake path, causing blue smoke after sits. A cracked head near an oil gallery is an edge case but possible. Prioritize seal condition and leak-down before suspecting casting damage. “I bet on the leakage of valves.” [Elektroda, krzych1-b, post #16993654]

I replaced pistons/rings without honing the cylinders—can that worsen starts?

Yes. New rings need proper surface finish to seat. Installing them without honing can reduce sealing and oil control, increasing smoke and crank time. Address mechanical sealing before chasing electronics. This step can make issues worse if skipped. [Elektroda, krzych1-b, post #16993512]

How do I verify the glow system beyond just checking the dash lamp?

Measure real current draw during preheat and crank, confirm fuse integrity, and inspect the bus bar for cracks, especially at the last plug. The dash light alone does not prove heating. Repairing a broken rail restored function in a reported case. [Elektroda, Alansi007, post #16991188]

Timing sounds perfect—should I still re-check it?

Yes. Verify with diagnostic software and the proper timing graph. A case with very high timing was corrected to ~42–48, which improved operation. Auditory judgment alone cannot confirm injection timing on VP37 systems. Trust measured values. [Elektroda, Alansi007, post #16975812]

What simple air/fuel checks can reduce unnecessary parts swaps?

Confirm the air filter is serviceable, then prove fuel supply integrity with a clear line or bottle test. If the engine starts fine immediately after a stall but struggles later, suspect suction leaks or non-return valves. Fix supply before replacing the pump. [Elektroda, mate1000, post #16970233]
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