2.5 TDI BFC Camshaft Photos - Comments Welcome

Hello everyone,

'So, I've gone from a 100 C4 (engine code: AAT) to a 320d BMW, and then to a 2.5 TDI A4 (engine code: BFC), only to discover that it seems to have a recurring issue with the glow plugs.'

Could you confirm that based on the photo?

Currently noticeable effect: The engine's power doesn't really kick in until around 3000 RPM (I know, there could be several things causing this...). Otherwise, the engine runs smoothly. I can't say anything about fuel consumption yet, as I've only had the car since today.

The car was traded in to a dealer by a retired man, and I recently purchased it with 66,000 km (A4 B6, manufactured in May 2003, 6-speed manual transmission).

I have a 1-year used car warranty on the car (which at least covers the engine and transmission). Is the dealer obligated to replace the brake pads if they have exceeded the 'break-in limit' specified by Audi?

Best regards,
Andi.

Turn the engine to TDC (Top Dead Center) or so that the cam lobes are visible. It's rather impossible to say anything like that.

Hey, 66,000 km? That's not much mileage. There shouldn't be any mechanical damage to the cylinder head with that low mileage. If it was driven by a retiree, the turbocharger (VTG) could be defective. Otherwise, you should remove the two cylinder head covers; it's a lot of work, but there's no quick or cheap way to get a diagnosis otherwise. Check all the camshafts to see if they look even, and make sure all the rocker arms are in place and in the correct position. If the cheap mini hydraulic lifters fail, the rocker arms could come loose or get stuck. In the latter case, there could be valve-piston contact, which would be bad.

Thanks for the quick replies!

Yes, this thing is like new and actually has 66,000 km on it.

Okay, to see wear in the 'working' area, you also need to see the cam . I've now taken a photo with the NW (North West) at OT (Outer Top), and now you can see something. What do you think of it?

I'm definitely going to have the lids removed anyway, but I'm already very curious...

Best regards,
Andi.

No matter how many photos you take through the oil filler, they won't provide an accurate diagnosis. Before you can see a change in engine performance or behavior, you need to be able to identify a wear pattern with grooves in the range of half a millimeter, not just a few scratches.

Since the angle of the cam remains relatively constant along its circumference, I would say that the cam itself shows no signs of wear. However, you can't see that just by looking at it, like you can with the others. }

You wouldn't expect to see that level of wear and tear with only 66,000 kilometers.

Best regards, Rainer.

If the image is not misleading, there are already pitting marks on the camshaft.
Most often, the rear camshafts are more affected. In any case, remove the valve cover.
You will have the least trouble if you insist on a replacement right away .

Thanks for the advice. I'll simply have an Audi mechanic check the issue.

Despite my search for improved performance, I took my car to the workshop. However, the test drives revealed that everything was perfectly fine (measurement report attached...). Apparently, the testing equipment malfunctioned, which is why it took them a full 2 hours.

It seems to me that they only compared the target and actual values at a single speed setting (I can't tell from the log what the target and actual values are...).

That means, for me, I probably need to find someone I know who has diagnostic software, so I can get a detailed log.

That's the current status...
Best regards,
Andi.

Now it's becoming clear to me: of the values in the log, only the lower one can be the target boost pressure. This would mean that I'm experiencing significant boost pressure overshoots, right?

That would also explain why he sometimes (with less pressure on the accelerator...) gets away faster.

Hello,

I have blacked out the last few digits of the vehicle identification number... it's not necessary for everyone to know exactly which car it is.

A log with VCDS from measurement block 11 would have been more informative. Based on this, we can only say that at the exact moment the value was recorded, the boost pressure was not ideally regulated, but it was still within an acceptable range. This doesn't really tell us much.

Best regards, Rainer.

Good evening.

I have just created a log, but unfortunately, it doesn't include the target values. However, in my opinion, it's already clear that the LD (likely referring to a specific parameter or process) is oscillating excessively.

What I've also noticed is that the injection start timing is at -3.0° at idle, isn't that too early? (See attachment.)

Edit 1: Regarding the start of the injection process, I misinterpreted the value before, but it is now correct.

'Edit 2: I've now added the correct logs (including setpoints, etc.) and posted a new diagram of the log data. It seems I need to work on the VTG (Variable Transverse Geometry) system...'


Best regards,
Andi.

I don't find the over-the-top reactions dramatic. That description is roughly accurate. What kind of air mass is involved in that?

For example, at a pressure of 2.5 bar and a low dosage (LD), the value is 1000.9 mg per injection.

Hello,

christians wrote:

I don't find the swingers to be dramatic.

"Beautiful" is one thing, but this is something else. It would be interesting to see if only MWB 11 and MWB 8 are logged simultaneously, whether the soot limit is reached during a pressure drop (which could indicate a "Bonanza effect" during adjustment, meaning the power output is not consistent).

Best regards, Rainer.

Attached is the requested log for MWB 8 and 11, combined.

I've adjusted the VTG (Variable Turbine Geometry) setting by half a rotation 'earlier' (using an Allen key), which has changed its characteristics. However, the driving behavior is still the same: it's quick up to 2700 RPM, and then there's even more power.

I'm going to reset the exposure to the original setting, as you can see, this will result in significant underexposure.

Best regards,
Andi.

Quote:

Attached are the requested logs for MWB 8 and 11, respectively.

Please provide the text you would like me to translate from German to English.