AGR Deviation in 2.5 TDI BDG Operation

Hello,

I have observed a significant deviation in the EGR (480mg/h compared to the target value of 250mg/h) during the engine's idle operation. Is this considered normal? How is the AGR amount actually measured?

When operating at full capacity, where the AGR also closes, I often have a slightly higher AGR, but the deviation remains below 10%.

Oh ja, and there's one more thing: The intake temperature is almost 4°C above ambient temperature when the engine is cooled down (although the ignition had been on for some time). Is this still okay?

Thank you for your help!

Lutz

Hello,

Quote:

I have observed a significant deviation in the AGR (approximately 480mg/h compared to the target value of 250mg/h) during the engine's idle operation. Is this normal?

Good question, I rarely paid attention to the over-feed operation. Reason: In over-feed mode, the injection amount is 0mg/stroke, and therefore the AGR is completely irrelevant. Only the cooling of the engine is more or less affected.

Quote:

How is the AGR amount actually measured?

With LMM.

Quote:

Oh ja, und noch etwas: Die Ansaugtemperatur beträgt fast 4° über die Umgebungstemperatur, wenn der Motor abgekühlt ist (aber der Motor war bereits einige Zeit eingeschaltet). Is it still okay?

Unpleasant but harmless.

If the car otherwise doesn't have any problems, I wouldn't worry.

Best regards, Rainer

Thank you for the responses.

I re-examined the log from the BDG further down and saw that the discrepancy is also present there. Another sign that it's normal.

I don't have any problems, except for a slight partial load issue when the engine is warm. It's probably the nozzles that aren't quite right, even though the idle control is still within the specified limits. The engine now has 135,000 km (however, it has been showing signs of wear since I purchased it at 121,000 km).

Greetings
Lutz

Wanted to let you know that it's also the case with my BDG, but you've already seen my log.

I can also see the increased AGR rate at full load.

Regarding the intake air temperature difference, I can provide you with the information.

Under what conditions is the efficiency of the air-cooled charge cooling actually measured?

Is your car "chipped"?

No, it's not chipped.

If the AGR values come from the O2 sensor, it could also be that the O2 sensor provides incorrect values here. This could then also lead to incorrect actuation of the AGR valve in the partial load range. Too much AGR -> rough run ??