Starting problems 1.9 TDI, 1Z

'With my A4, I'm experiencing the following problem: Since yesterday, it's been acting up when starting. It runs for a maximum of 2 seconds and then shuts off. This happens 4-5 times, and then suddenly it runs normally again. The next time I start it, it works normally!'
Mileage: 185,000 km. Spark plugs have not been replaced. Diesel filter has been changed.

mi15hu wrote:

With my A4, I'm experiencing the following problem: since yesterday, it's been acting up when starting. It runs for a maximum of 2 seconds and then shuts off again. This happens 4-5 times, and then suddenly it runs normally again. The next time I start it, it works normally! Mileage: 185000 km, spark plugs not replaced, diesel filter replaced,

Please search for "immobilizer". The ignition coil in the ignition switch might be faulty, or your ignition key might be defective.

Hello mi15hu,

'A bit more information would be helpful. What steps have been taken so far to identify the cause of the problem? Are there any relevant logs available? Since the car initially starts, I wouldn't suspect a faulty glow plug system. There are many potential sources of error, ranging from air bubbles in the fuel system to misaligned timing, and even the infamous KW screw.' Please provide more detailed information (logs) about the problem.

Please search for 'immobilizer'. Possibly, the reading coil in the ignition switch is faulty, or your ignition key is defective.


I hadn't even thought of that! That's quite understandable, of course.

Hi Marco,
If your problem still hasn't been solved:
I had the same starting problems. On my 1.9 TDI 1Z, a connector on the cable of the reading coil (immobilizer) was slightly loose. A drop of hot glue to secure everything, and the starting problems were gone.
Best regards, Mick.

Hey guys!

'Question: If the transponder coil or key were defective, wouldn't the engine control unit lock after a few attempts?'

Troubleshooter wrote:

If the reading coil or the key were defective, wouldn't it lock the control unit after a few attempts??

That would be news to me... I once had a "key only" replacement made for my Golf for certain reasons (i.e., without a transponder).
I tried using that to explore the behavior of the WFS, and I made quite a few "failed" attempts to start it.
But every time, on the next attempt with the correct key, it would work perfectly normally.

That would be news to me... I once had a 'key only' replacement made for my Golf for certain reasons (i.e., without a transponder).
I tried using that to explore the behavior of the WFS, and I made quite a few 'failed' attempts to start it.
But every time with the next attempt, using the correct key, it worked perfectly normally.

I can only confirm that. I also had problems with the WFS (likely referring to a specific system or component) earlier this year, but in a Passat 3BG. If the control unit were locked, then the car would never start again after the error was resolved...

hello,

This problem can also occur if the connections to the alternator are faulty, or if the carbon brushes are worn out.
The control unit then reports an implausible signal from the alternator.
replace the regulator and connections, including the connection of the alternator to the battery at the starter.
verschandeln with fine sandpaper and reapply polishing compound before reinstalling.
Then it usually works again.

This problem also occurs if the connections of the alternator are not okay, or if the brushes are worn out.
The control unit then reports an implausible signal from the alternator!

Umm... The issue is that the engine shuts off after a short time. The engine control unit probably isn't turning off the engine because of an implausible signal from the alternator. So, what does the answer have to do with this thread?

Regards,
Private.

'I occasionally experience the same 'problem' with my 35i 1Z '95. The maximum number of times it has stalled is three. I initially thought it might be the key, but it wasn't any better even with the spare key.' I'm actually leaning towards the reading module of the WFS, although 'typing' is more like buying a lottery ticket. (Is there a reasonable way to diagnose that?)
Also, außerdem gibt es immer (wenn der Motor aus ist) eine Luftblase, die aus dem Kraftstoffzulauf der Pumpe kommt. (ungefähr 5-10 mm am ersten Knick). Aber ich weiß nicht, ob ich dafür die Pumpe verantwortlich machen kann.
What I'm more interested in is whether anyone has experienced this starting problem for a very long time, and whether there was any change or... A deterioration was observed.

knödeldidödel wrote:

I'm actually leaning towards the reading module of the WFS, although "tippen" is more like buying a lottery ticket. (Is there a reasonable way to diagnose that?)

Use VAGCOM to search for the WFS. Somewhere within the measurement data, one can find (with a bit of luck) numbers related to authorized and unauthorized start attempts.
I'm not sure how long they will be stored for...

In addition, there are error entries labeled "Motor Control Unit locked" that apparently remain for 50 start cycles after the last error occurrence.

Okay, for me (35-year-old male, 1 child, born in '95), I can only read values 1, 2, 3, 8, and 15. Is that correct? Wouldn't WFS be 25, or am I talking nonsense?

@ulf

AFAIK, the attempts on these control units are not yet being logged. I also experienced the same problem with the WFS during the winter, and nothing was logged.

@knödeldidödel

You really should try the WFS. The 95 has one.

Regarding the air bubble: I've always had that problem, even when the engine was running. It ran perfectly smoothly, no hesitation, absolutely nothing.

Best regards, WarLord.

Hello 'mi15hu' and 'knödeldidödel'!
I drive an A4 1.9 TDI manufactured in 02/1995, and I'm experiencing the exact same problem.
Your description of the problem perfectly matches the issue I'm experiencing.
I start the engine, and it runs for about 1 second, then it dies again.
After 2-5 attempts, it will finally start.
The error memory has already been read.
It didn't achieve anything. No error was saved.
The error was gone for a long time, but it's now appearing more frequently again.
I now believe that this is likely a loose connection or something similar.
I will check the connection to the reading head at some point.
Once I find the error, I will get back to you.
Otherwise, my 'A4 TDI' is a fantastic vehicle. Driving is fun!

Regards,
FRED

"My 1Z does that occasionally too. A quick fix is usually to remove the key, turn it, reinsert it, and essentially "pre-glow" it." The WFS device sometimes seems to be slow in detecting the transponder (possibly due to system voltage?).
However, I've also encountered the problem where nothing works anymore. In that case, it helps to disconnect the battery for at least 3 minutes (less time won't work!) to "reset" the system. We came up with the idea together with a nice person from ADAC, when my van, after a completely trouble-free journey and a stop at the gas station on the highway, suddenly refused to start.
The premise was: what do you do when the computer crashes? Close all windows and restart. (That was the comment from the ADAC technician, after he realized that even a T3 can have a Window Flush System (WFS) integrated with the control unit, which you can't just disconnect.)
I have no idea why or under what circumstances this complete blockage occurred. Definitely not due to weather (static electricity...) or system voltage dependency.
Perhaps this will help further.
Hi Marcus,