I now have a second problem: since last winter, the engine has been exhibiting the following behavior, initially sporadically and then constantly:
When the engine is cold, the starter doesn't turn as quickly as usual (less than one second), but rather takes what feels like two to four seconds.
After that, the engine will start, but there will be some smoke for the first few seconds.
The issue only started occurring after all six spark plugs were replaced (replaced in the summer, problem started the following winter, but of course, that could also be a coincidence).
Initially, as I mentioned, it happened sporadically, sometimes with a lot of cranking and smoke, and sometimes without.
Towards the end of winter, the engine always started poorly when it was cold.
The dual temperature sensor is about 1 1/2 years old and, according to VCDS, provides plausible values. Also, the glow plug symbol stays on longer at cold temperatures than at warm temperatures, which suggests that the preheating time is correct.
All six glow plugs have been tested, and they all appear to be working correctly.
Today, I removed the cover of the main switchboard (MSB) and checked the fuses: all three (2 x 60A, 1 x 15A) showed continuity and a resistance of 0 ohms.
When the preheating indicator light turns off, the interior light doesn't become noticeably brighter.
I performed a diagnosis of the actuator: there's a loud and distinct clicking sound coming from the area of the engine control unit (ECU) when the glow plug relay activates, but the battery voltage only changes by about +- 0.5V when it switches.
The glow plugs do not generate any error messages in the fault memory during the BDG (presumably referring to a specific diagnostic process or system).
The idea is that it's related to the glow plug system, but I'm not sure where else I could look.
My hope was in the fuses in the MSG, but those are okay.
Does anyone have any other ideas?
I recorded both starting procedures. The first video shows the engine starting in a cold state at an outside temperature of -6°C after being idle for five days. The second video shows the engine starting after approximately 30 minutes of driving in a warm state.
Thank you! Simply say if something doesn't work, instead of trying to convert or do other things.
Of course, .mov videos are supported. Simply upload the video and let me know if the format is not accepted. Awesome, right?
Because we don't want to have to deal with dead links or obscure conversions after a short period of time, right?
Okay, I'll do that next time. I thought it was chosen that way intentionally (perhaps due to file sizes) or that it simply wasn't technically possible.
In the "Worst Case Video," it's very clear that not all burners operate evenly.
I would check the following in this order:
- Glow plugs. Older TDI engines have a relatively high compression ratio, so that at temperatures above 5°C, preheating is not necessary. In your engine video, the engine temperature at startup is unfortunately not known , but it is the case that the compression ratio is lower in newer TDI engines. This has some advantages, but also the disadvantage that cold starting is worse and that preheating may be required at higher temperatures. Current engines also glow during operation for emissions reasons.
- Air in the fuel injection system? If applicable, have the O-rings on the diesel filter been replaced?
- Compression test: This is where things can get expensive, as repair costs can quickly become substantial.
How many kilometers has the engine been driven, and what is the oil consumption like?
Thank you for the tips.
"All six spark plugs have already been tested, and according to the workshop, they are technically within specifications."
The car has 139,000 km on the odometer, and the glow plugs were replaced about 14 months ago. This behavior has only started since all six glow plugs were replaced by the Audi workshop 14 months ago.
The oil consumption is practically zero (or so low that no topping up is required between inspections) - except for an initial consumption of approximately 0.7 liters during the first 10,000 km.
Could it be that instead of the candles themselves, there's a faulty cable somewhere that's producing leakage currents, and that's why the candles aren't receiving enough power? As far as I know, this wouldn't be recorded as an error.
Edit: My last question is actually addressed sufficiently in link one. Theoretically, it's probably enough if the mechanic had oily fingers and touched the glow plugs with them.
Okay, so I think the first thing to do is to re-check the glow plugs and, while doing that, also check the voltage and current flow.
First, you could directly measure the voltage at the filaments to see if there's any voltage reaching them when they're supposed to be glowing, and how high that voltage is. That would tell you whether the control circuitry is working correctly.
Florian320 wrote:
When the preheating indicator light goes off, the interior light does not become noticeably brighter.
"That's normal. The extinguishing of the preheating symbol only indicates to the driver: 'From now on, the engine should start without any problems.' In reality, the preheating process will continue for some time without the driver being aware of it."
Warning: From here on, what follows is my own, potentially inaccurate, knowledge.
I once heard that there are different types of glow plugs with varying warm-up times and operating voltages. However, I suspect that vehicles with semiconductor-controlled glow plugs (including individual monitoring) now use these. Since you mentioned a clicking relay, I assume this doesn't apply to your situation.
Since you mentioned a slight voltage drop, incorrect glow plugs with insufficient current draw would be consistent with your other symptoms. Can you read the type/part number of the glow plugs? Then, let's check what's actually supposed to go into the engine...
Perhaps someone else knows something similar.
The car is coming to the workshop anyway on Monday (the one that installed the spark plugs, it's an Audi service center).
Even though they should theoretically know what they're doing and which candles to use, that would definitely be a very helpful clue, and I'll suggest it to them.
I have to admit, I'm too afraid to take the spark plugs out myself and check which ones they are. If I mess something up, it could get really expensive, so I'd rather leave it to the professionals at the workshop.
I admit, I'm not brave enough to take out the spark plugs myself and check which ones they are. If I mess something up, it could be really expensive, so I'd rather leave it to the workshop.
A re-measurement or verification would be sufficient.
I think so too.
But in the video, the temperature was actually -6 to -7 degrees Celsius, and the car had been parked for five days.
I think, given the circumstances, the time was within the acceptable range.
"And yes, it sounds like it's not running on all cylinders. That would also make sense, because if at least one spark plug isn't working properly, the corresponding cylinder won't be working correctly for the first few seconds. You can also see in the video that the smoke stops after about 15 seconds."
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