AFN Engine Starting Problems

Hello everyone,

"I'm experiencing different starting problems with my Sharan 1.9 TDI AFN, depending on the coding in the engine control unit (part number 028 906 021 JJ). Once it starts, it runs perfectly."

If it's programmed for a manual transmission, I have to crank it for 5 to 15 seconds before it starts.

"However, if it's coded for an automatic transmission, it starts up quickly (1 second), but it makes a very loud rumbling noise while doing so. Every second or third time, it gets even worse; I'm not sure how to describe it, but it seems to misfire. (The engine starts to jerk back and forth, and you have to turn off the ignition again)."

Is there anything that can be done with VAG Com 3.11?
Or perhaps the engine control unit has been tampered with through chip tuning, and I should instead consult a chip tuning specialist?

Best regards, Stefan.

Hello Lymatrak!

Lymatrak wrote:

... Do you think

there's anything } you can do with VAG Com 3.11? }

Before we can really help you with this, or help the homeowner, you need to provide us with the unlocked (and uncracked) serial number of your VAG-Com version. We can't assist you further without it, for obvious reasons.

What is the year of construction?

If you had the vehicle's engine chip modified by a tuning specialist, please contact them.

Besides that, if you're having trouble starting your car, using the search function will yield over 100 results, all of which offer potential troubleshooting steps.

Best regards from Munich!

Difference between GmbH (limited liability company) and AG (stock corporation):
The starting quantity characteristic curve of the switch only becomes active above a certain temperature.
certain engine speed, fuel is released - in automatic coding, the amount is independent of the...
Temperature released.
Test: Switch to single-cylinder mode and disconnect the temperature sensor -> The car starts immediately .
The reason for the poor starting performance is, however, a starter motor speed that is too low.
The cause could be a dead battery, or it might be related to the location, which also...
causes the "malfunction".

Best regards,
Micha

Hello!

He probably means the following by "Falschlauf":

/viewtopic.php?t=1241&highlight=81kw

But everything should be findable through search .

Best regards from Munich!

Lymatrak wrote:

However, if it is coded for an automatic transmission , it starts quickly (1 second), but it makes quite a loud rumbling noise. Every second or third time, it gets even worse, and I'm not quite sure how to describe it, but it seems to be a kind of misfire. (The engine starts and stops repeatedly, and you have to turn off the ignition again)

In my opinion, this happens because the automatic transmission coding doesn't know about the dual-mass flywheel (DMF) and therefore doesn't block the speed range of the DMF's natural resonance: which is roughly around 400 rpm, if I recall correctly.
"If the engine runs for a longer period in this range, the dual-mass flywheel (ZMS) is likely to be damaged quite quickly, in my opinion."

Quote:

Do you think there's anything you can do with VAG Com 3.11 there?

Yes: avoid the AG coding.

Quote:

Or perhaps the engine control unit has been tampered with through chip tuning, and I should rather consult a chip tuner?

I doubt that. AFNs are often poor warm starters due to software issues (see also Wiesel's answer).

Hello, thank you for the helpful suggestions.

Due to this different behavior depending on the encoding, I assumed that it must be a software problem.
Now, with this new knowledge, I suspect I understand the real problem. My starter motor failed about 2 years ago, and I had to replace the brush holder at that time. It seems like it's starting to fail again.
I just placed an order for a new one.

Best regards,
Stefan