Golf 3 TDI: Cold Start Problems & Solutions

Hello everyone,

I've read through the forum and tried various solutions, but I haven't been able to find a successful one. I apologize if this topic has been discussed many times before, but I would still appreciate any help you can offer.

The following problem:
"When starting the engine cold (not just overnight, but also after a few hours of standing when the ambient temperature is reached), it takes a very long time to start (and then it produces a lot of white/gray smoke). It runs on three cylinders for a short time, then there's a click inside the car (I think it's a relay, but I'm not sure which one ???), and then it runs normally."
Yesterday, things got so bad that I had to drive around for so long that the battery ran out!

PS: It was stored over the winter (March-December). However, I also tested it several times in temperatures as low as -25°C, and it started up perfectly. The problem has only appeared in the last 5-8 days, after being out of storage.

When it's warm, there are no problems; it starts immediately, and there's no loss of power or anything like that.

What I have already done Technical articles: General information about starting problems: largely completed:
The diesel fuel is flowing freely (I also have a transparent hose connected to the return line).
Diesel filter replaced, diesel is flowing.
Glow plug system checked (measured and visually inspected). Injector nozzles removed and checked to ensure they are preheating. All four glow plugs are working.
Error memory: no entries found.
Crankshaft pulley (Schaube) securely fastened; was refurbished last year.
Valve timing checked with (Dorn and arrtierline) - okay!
Relais 109 wurde letztes Jahr getauscht auf anderen verdacht !?! Broken??
The starter motor is working perfectly.
The battery is also okay, but I tested it with a new one as well, without success .
Compression test: okay, sounds good.
The injectors were inspected at 170,000 km, checked for pressure and spray pattern, and were refurbished by Bosch.
The fuel injection pump was replaced at the beginning of last year (0.

Okay, I'm currently at a loss and don't know what else it could be.
I only have access to the trial version of VAG-COM, which is not sufficient for a full license at the moment.

Vehicle data:
VW Golf 3 TDI.
Engine code: AHU
Mileage: 220,000 km
BJ.12/96

I hope you can help me quickly with your knowledge .
Thank you in advance!
Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

It might be a good idea to try something like that.
futile event trigger
MWB 5 zu loggen. That's what you see.
at least, how fast it spins.
When and how much he injects.
Have you checked the temperature sensor?

Best regards, Klaus.

Hey, thanks for the reply.

Okay, so when the engine is cold, all the temperature sensors (fuel pump, intake air, and coolant) show similar readings, with a difference of about 1-2 degrees compared to the ambient temperature.

MWB 5: I'll definitely log that and note it down during the startup process tomorrow morning.

It's not possible to test the relay itself, or if it's the problem, without another vehicle with a 3 TDI engine to compare it to.
But if it's running on 3 cylinders and there's a clicking sound in the relay area, it suddenly starts running on all four cylinders!

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Good morning, everyone.

Here is the LOG MWB 5 as requested. /viewtopic.php?t=20813
I hope this helps!

Yesterday, a new symptom appeared: when I let the clutch out (while the engine is still running) or use the engine brake (going downhill), the engine doesn't respond to the accelerator anymore.

Ich muss erst die Kuplung betätigen und ihn in den Leerlauf runter lassen , dann nimmt er sofort wieder das Gas an ?? Help!!

If I don't let it idle (don't engage the clutch beforehand when I need to slow down), and I use the accelerator, it works normally.

What could that be? Is it all connected?
There were no errors found this morning.

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

What is the injection start timing? A delayed injection start can cause starting problems! Check with VCDS!

"Although I only see clumps of numbers,"
But as far as I can tell, the starter motor is turning.
With a mere 200 revolutions per minute?

Best regards, Klaus.

Thank you for your responses.

@T3Surfer I'm having a problem where I can't seem to get rid of it. Even when I do, it starts up and runs roughly on only three cylinders, then it dies. It won't respond to any throttle input or anything.

Towing doesn't help either.


@Klausel: I may only be seeing a bunch of numbers, but as far as I can tell, the starter motor is turning.
With just 200 revolutions per minute?

(Data clump) I don't understand this now. When I download it from here and open it with Excel, it looks like this: http://s2.imgimg.de/uploads/LOG4e86da12jpg.jpg

Yes, it's rotating at approximately 200 RPM, which, according to your statement, is too slow, but (in my opinion, it has never been faster).
Replacing the starter?

I'm not sure what to do next. Could it be related to the Relias 109? It seems to be working, but only on 3 burners. It's only a year old, but you never know!

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

The mysterious "109" activates the voltage for the engine control unit. Connect a test lamp or LED and you'll quickly know for sure.
Which cylinder is not firing or failing to start? It's always the same one. If that's the case, try swapping the pressure control valves at the outlet of the ESP (Electronic Stability Program) with each other. They can sometimes get stuck at a low starting speed. I suspect you have a corroded positive cable on the starter. This is a common problem with these models. It causes unnecessary resistance and, consequently, a reduced starter speed.

Best regards,
Roberto

Here's a picture for illustration.

Okay, I'm ready. Please provide the German text you want me to translate.

Hello,

Okay, so I have another short list here (basically, a rundown of what I know and can do):

I checked the starter motor (positive cable) as described and visible in the photo from LZ, and it looks very good. I cleaned it again and connected a new battery, and it seems to be working better (it's only about 2 years old).

Furthermore, I recently purchased a new Relias 109, but it didn't improve the situation.

I've double-checked the timing using a dial indicator and straight edge, and also marked the top dead center (TDC) on the transmission. It's correct, not misaligned. The screw on the crankshaft pulley is also tight and there's no play.

We managed to get it started today, and after about 200 meters, it finally fired up – a huge cloud of white smoke came out, which was incredible (I think it was unburnt diesel)!!
The start of injection after top dead center (TDC) is at 1.3 to 1.5 degrees. It fluctuates slightly at idle, which is 903 RPM.

"What I've noticed is that when I give it gas while the engine is idling, there's a slight ringing sound coming from the area around the injectors (although it's hard to pinpoint exactly). However, the engine still runs smoothly and quietly."
Faulty injector(s)??? (I'm leaning towards that, as it seems to only happen when the engine is cold, and it might be dripping, the needle might be stuck, or something like that?)

And the valves sound different; I've heard that noise twice before, last year, before the new head was installed. It's a completely different sound.

When I disconnect the injector driver, the engine starts running erratically and seems to be trying to adjust itself (which I think I can probably rule out).

I hope you can help me figure out if the problem might be the injectors. They were replaced about 50 kilometers ago, but you never know. Is there a way I could test them myself, and what other tests could I do?

P.S.: After being towed, it started running normally again and started up immediately; there was no loss of power or error messages. However, after standing for a few hours, it wouldn't start anymore (the ambient temperature didn't seem to make a difference!!

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Hello.
"This is a real pain. Try spraying the area around the fuel injectors on the cylinder head with a leak detection spray. You shouldn't see any bubbles forming. It's possible that whoever installed the injectors forgot to use the copper sealing rings, installed them incorrectly, or reused the old ones. You can also make your own leak detection spray by mixing water and a little dish soap in a spray bottle."
Perform the "Hoppeltest" compression test and verify the results.
I strongly recommend a structured approach, perhaps with written documentation. If the initial engine speed turns out to be too low, start there. Are there any documents available for the work that has already been done? Why was the ESP (Electronic Stability Program) replaced? Did the engine run properly after the replacement? What compression was achieved during the inspection?
Whether the engine is preheated at these temperatures doesn't matter. The engine must start even at -15°C without preheating. If the 109 is acting up, you'll notice it clearly during the starting process – it will stall.

Best regards, Roberto.

Hello Roberto,

Okay, I'm sorry, I'm not really a mechanic when it comes to things like that.
I had tried to look through some articles and forum posts to see what I could find (printed out and clipped, that's how I documented it.

"I have the compression pressure reading here on this note from VW (which I had checked by the service department)."
1st cycle: 24 bar, 2nd cycle: 24.2 bar, 3rd cycle: 24.4 bar, 4th cycle: 24 bar.

I installed the nozzles myself, after checking the glow plug system, and of course, with new copper seals. Regarding the leak detection spray, I only used water.
Sure, here is the translation of the text from German to English:

"Repeated!"

"The fuel injection pump was replaced last year along with the crankshaft pulley because it stopped supplying diesel (I don't know the exact reason). I only know that the pump's impeller no longer offered any resistance when turned, and it wasn't pumping anymore."
Yes, it ran perfectly after the replacement and with the dynamic settings adjusted on the pump, until recently.

Quote:

The engine must start at -15°C without any preheating.

If the 109 is acting up, you'll notice it clearly during the starting process; it will stall. }

Okay, to be honest, I've never tried it without preheating, regardless of whether it's the new 109 or not!

What speed does the starter motor need to reach when starting the engine?
Should I replace it? I've cleaned all the cable connections, made sure they're free of corrosion, and sprayed them with Contact 60, but that's all I've done (regarding the RPM).

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

Hello,

Compression is suspect. The threshold for unacceptable deviation is 19 bar, or differences greater than 5 bar.
Before installing a new starter, also check the battery's ground cable at all connection points. Look for contact resistances in the crimped cable terminals, especially regarding the stranded wire (referring to "Grünpan"). Once you're sure all doubts and potential issues have been eliminated, and you don't observe an increase in the starter's speed, I would recommend testing the starter directly using jumper cables. The starting speed should be 300 RPM.

Regarding the starting procedure: When it's running on only 3 cylinders, is it always the same cylinder that's failing? Try touching the exhaust manifold to feel for temperature differences. This will help you pinpoint and observe the problem.
How is the condition of the oil leak hoses on the nozzles and ESP? If there are any leaks, air can be drawn in when the system is stationary, and the ESP may run partially empty through the return line.

What is the typical voltage on board when the vehicle is stationary and when it is starting?


Best regards, Roberto.

Hello everyone,

Quote:

Before you install a new starter, also check the battery's ground cable to all connection points. Check for contact resistance in the crimped cable lugs – a common issue like "Grünpan" on stranded wire.

Make sure all doubts and potential shortcomings have been eliminated, and if there is no increase in the starter's speed, I would then test the starter directly using jumper cables. The starting speed should be 300 RPM.

I did that, and lo and behold, it's now running at approximately 320 RPM. The problem is fixed (the faulty ground cable was the issue).

I've now found the solution, or rather, the cause of the problem, with a friend (a car mechanic). The fuel injection pump (after we got it running) is making very strange noises (knocking, and it starts to scrape/you can feel the scraping if you put your hand on it), and the noise gets louder as the engine speed increases.

I think you're not building enough pressure when starting, and that's why it's getting worse now that it's in a warm state, and it's probably just starting or about to start. Am I right?

"When I'm driving (we already took it for a test drive) and I release the accelerator (let it coast), it doesn't accept the accelerator again. I have to put it in neutral (release the clutch) before it will accept the accelerator again?! Could this be related?"

Can I fix the pump myself, or what could be broken???
I still have the old pump at home that no longer pumps diesel.

I don't want to waste any more money on another pump, especially if it only lasts another 50,000 km (it was a refurbished pump)!!!

I hope you can help me .

MFG }

Okay, let's get the pump out and check out an auction house. Search for the seller "topxit"; they seem quite reputable. And the price range is reasonable. It's not worth the hassle to try and fix it yourself, especially considering the damage you've described, which suggests some parts are already worn. At this point, also have the injectors checked to ensure a clean spray pattern, so that pump debris doesn't negatively affect their performance.
Did you have the replacement fuel pump, which is now malfunctioning, refurbished by a Bosch service center?
I assume you're filling up with diesel? Or were there any experiments with alternative fuels?

Best regards, Roberto.

Hello LZ,

Okay, I'll have the injectors replaced. Yes, I also bought the fuel pump from Action House and had it refurbished at the Bosch Diesel Center. It's been about 50,000 km since then (total mileage of the pump is approximately 160,000 km). Yes, it's been over a year now, since January 08.

Yes, another pile of money being put into this car for repairs, and who knows what else will come up. I'm slowly losing the desire to do this anymore.
No, I haven't done any experiments; I just used regular diesel from the gas station .

Does that also have something to do with the fact that it doesn't accept any more gas when you let it idle? Does it only start accepting gas once the idle speed is reached?

Best regards.

It sounds like a failing vane pump... perhaps demonstrate it to the Bosch service center? This vane pump is a relatively inexpensive replacement part, but it requires a complete disassembly of the pump for installation.
Why is the pump failing right now? The long periods of inactivity, plus any potential water in the diesel fuel, could be the reason.
Just get it fixed and be done with it. Replace the diesel filter or try unscrewing the drain plug.


Best regards, Roberto.