AFN Cold Start Issues & Engine Control Unit Replacement

Hello everyone,

I'm new here and I have a few questions about my problem that I'm hoping someone can clarify. I've already read a lot, but somehow I'm still stuck... I drive a Golf 3 GTI TDI with the engine code AFN, and it has almost 200,000 kilometers (approximately 124,000 miles) on it. The timing belt was replaced at 150,000 kilometers (approximately 93,000 miles) by the previous owner.

Okay, I replaced the glow plugs last December at around 170,000 km because I felt like my car was having trouble starting. After the replacement, it wasn't significantly better. This year in May, I had to crank the engine for a longer time, about 4-5 seconds. However, when I was on vacation in Croatia in May (I was near the sea, and the nighttime temperatures weren't much higher than in Germany), the car started without any problems.

Since May, I've been having to crank the engine for a minimum of 10-15 seconds before it starts. A white cloud comes out of the exhaust (unburned fuel?).
Last week, I visited the VW dealership, where they replaced the gear selector (part number 28871900), two temperature sensors, and the blown glow plug fuse.
The problem persists, and the mechanic told me that my steering control unit isn't outputting any voltage. So, I obtained a used steering control unit with the same part numbers (0281001472/473 028906021DF). However, the new used unit produced three sporadic errors that my original unit didn't. Of course, the engine didn't start with the new, used unit. The keys haven't been reprogrammed either. I then sent the used unit back to the dealer, who will repair it free of charge and with a warranty. The crankshaft bolt was also checked (and was okay). The dealer also tested the glow plugs. All four glow plugs are receiving 48V (4 x 12V).

Okay, now for my questions...

-Could it really be due to the starter motor, even though the problem with starting has been gradually getting worse since May?
-Does the engine start more easily when it's cold if I disconnect the coolant temperature sensor? If so, where is the sensor located?
-Why would the engine start better if I disconnect the sensor? Doesn't the signal from the sensor go to the engine control unit (ECU) and then to the glow plug system?
- The fuel filter has been replaced.
-Why isn't the engine starting with the used starter generator (SG) and the correct part number? Could it be due to a defect in the used SG?
-Can I get a different service grade (SG) for my Air Force Number (AFN), or does it have to be the same number?

Those are my questions. Perhaps there's a TDI mechanic near Neubulach, CW, or BB who could take a look at it, in case it doesn't work with the repaired SG?

Thank you in advance for your answers, and I wish you all a pleasant weekend.

Best regards, Daniel[/b]

So, if the control unit is defective, the vehicle won't start at all.
White smoke could be caused by a leaking head gasket - are you losing coolant?

Auf jeden Fall würde ich mal den Fehlerspeicher auslesen lassen, vllt. ist der Spritzbeginn verstellt oder der Temp. Sensor failure.

Best regards,

Hello.
What is a ZKD? Could you perhaps spell out the abbreviations first?
An den Steuerzeiten wurde nichts geändert. Verstellt sich sowas mit der Zeit?Ich verliere kein Kühlwasser. AEverything is close.
The diagnostic trouble codes (DTCs) showed no errors in the control unit I'm currently using, but they did show errors in the used control unit I purchased.
Thank you for the response.

ZKD = Cylinder head gasket.

Interessant wären ja auch mal die Fehler die im 'neuen' SG abgelegt werden, was sind es denn für Fehler?! Hängen die überhaupt mit der Motorsteuerrung zusammen oder beziehen die sich auf irgendetwas anderes? Lesespule etc.

Valve timing can change with a loose pump . White smoke may occur, and the pump may be set too early!






Ibiza AFN with 371,000 km.

Hello everyone.
The new starter generator was installed today. And wouldn't you know it, it still doesn't work when the engine is cold. I'm starting to despair... Luckily, I didn't buy a new starter generator from that expensive place. That would have cost 1200 euros right off the bat, and it wouldn't have helped. Does anyone else have any ideas about what it could be? I would be really grateful for any suggestions.
Have a nice weekend.

Boro wrote:

...It would also be interesting to know what errors are being stored in the "new" SG, what kind of errors are they?! Are they even related to the engine control unit, or do they refer to something else? Like, reading coils, etc.

Do you actually want to receive (inexpensive) help, or is this just a place for you to vent your frustrations with a completely transparent and open forum??

It would probably be better if you first answered the questions from the people who are trying to help you! ...at least out of basic courtesy, man!

Without any error code information, no one here will be able to really help you - sorry.

Good morning, everyone.
I'm not looking for a place to vent my frustrations. Sorry, I didn't mean to imply that. The error memory of my new device is now showing nothing. It was installed and checked yesterday. (According to the seller, the old device's memory was repaired and everything was erased). If the error memory of my old device had been useful, I would have a printout from the seller right now.
Next week, I'm going to have the pump checked, and possibly the timing belt as well. What happens after that remains to be seen.
Thank you for your suggestions, nonetheless.

Hello,

I've also been having starting problems with my Passat for the past few months.
Then suddenly, error code 1117: Load signal generator terminal!

Ich also Meßgeraet raus Spg. gemessen 14,3V! Lima, okay.
"Gutmann," the technician said, "your starter current might be too high."
So, everything is okay according to the measurements.

It was the battery. After a stress test, where the voltage dropped to 3.7 volts after only 2 seconds, my supervisor said, "That battery is dead." Normally, a battery should still have a little over 9 volts after 10 seconds in this type of test.

Okay, so I put in a new battery, 80 Ah, which was "damn expensive," and it was installed, and everything was fine.
The old car probably has a faulty fuel cell. My fuel consumption has increased by over a liter.

Markus.

bigbacke wrote:

-Could it really be due to the SG, even though it has been gradually getting worse with starting since May?

No, an MSG doesn't gradually misalign.

Quote:

-Does the engine start better when it's cold if I disconnect the coolant temperature sensor? If so, where is the sensor located? -Why would the engine start better if I disconnect the sensor? Doesn't the signal from the sensor go to the SG (Steuergerät - control unit) and then to the glow plug system?

The AFN glow plug control is integrated into the MSG (Motor Steuergerät - engine control unit). Disconnecting the connector (for the AFN, it should be a 4-pin connector near the engine block, close to a water outlet) simulates a very cold engine and increases the starting amount accordingly. Whether it will help you -> try it out.

Quote:

-Why doesn't the engine start with the used SG and the correct number?} Could it be due to a defect in the used SG?} Because it hasn't been programmed to the WFS-SG?

Okay, later today my car (Golf) is going to a different workshop. I'll give them the instructions about adjusting the fuel pump. Then they should also check the battery voltage, etc.
I will get back to you on Tuesday at the latest, or Wednesday at the very latest.

Regarding the "coolant temperature sensor" issue: When I disconnect the sensor, my Golf starts easily, provided the outside temperature allows it. In other words, it's very difficult to start in the morning, but it starts immediately in the afternoon if the car has been standing in the sun all day.

Okay, hello everyone. I'm reporting in quite late, as I was still on vacation. My Golf is running smoothly again...
It was due to a worn/defective drive sprocket (likely the crankshaft sprocket) for the timing belt. This caused the timing to be misaligned, and as a result, my Golf wouldn't start when it was cold.
Thank you anyway for your help/answers.

Best regards, Daniel[/b]