[T6_measured] 01-Engine - Built-in test for EGR

[mmi]

Have done another run. Just one glitch, managed to press marker button not long after.
Cruising on motorway at about 70 in 7th Manual, so hoping results should be clearer, revs should have been fairly consistent around the 2000ish mark.
Tomrrow changing the crankshaft position sensor so will try and do one after sensor change.

Thanks. At the moment of the glitch (orange) quite a few other parameters do have a hiccup, too.
The glitch is 2.7 seconds before the marker.

 

[wannaT6]

Thanks mmi, really helpful. I'll have to figure out how to plot these graphs like you do at some point. Other parameteres above feel like results of ecu confusion from the bad sensor data in my mind and from the feel of the drive, ecu over/under fueling around the glitch or bad data it was getting causing jumpiness and engine stutter.

Crank Position Sensor is now changed for a VW OE one. First things I noticed, start took less turns of the engine, sounds smoother just after starting even when cold. Gear changes in auto requiring a downshift under heavy accelerator pedal input from D6 or D7 were quicker and less hesitant.

Took her for a long drive this morning to replicate the 70mph 2000 rpm style of driving in 7th manual that reproduces the glitch. Felt great to me by comparison to many previous journeys, rock solid and no issues over a 45 min drive of about 60 miles. Setup logging as before, but some sort of problem with vcds/my laptop meant it saved the file again with 0kb, slightly annoying I can't share the data on that run so will try again at some point.

As the problem has been so sporadic I will hold out from rejoicing and declaring 100% sure fixed, but already feels like the issue is resolved.

Can't thank you guys enough on this forum. Without you and VCDS testing and that previous T6 post from ben3042 (204 DSG intermittent momentary power loss), I'd have been wrongly guessing at EGR related problems, (suggested by an ex-BMW mechanic, who changed the wrong sensor, the camshaft position one) for a long time at much higher cost!

Potentialy another win for T6 forum and VCDS and just in time for xmas road trips with the fam.

Best wishes and much thanks.

 

[mmi]

Other parameteres above feel like results of ecu confusion from the bad sensor data in my mind and from the feel of the drive, ecu over/under fueling around the glitch or bad data it was getting causing jumpiness and engine stutter.

Agreed. Indeed assuming the crankshaft sensor is the root cause. Could even expect to see some improvement in fuel economy...
Anyways, thanks for the feedback, and please keep us posted how things are over your xmas trips.

Thanks mmi, really helpful. I'll have to figure out how to plot these graphs like you do at some point.

Attached an Excel (2016) sheet for plotting VCDS data (actually the same as data&plot above)

In Excel open your fresh CSV-logfile
Copy columns A-Y

Open attached Excel sheet (the sheet takes first 16142 rows of data for plotting - about 40 minutes)
Paste (values) - into columns A-Y (by doing full columns old data is cleared)

In the sheet the axis-settings are focused to highlight the earlier glitch. Manipulate axis-scaling etc. as needed for new data.
The plot has all the data items already selected - just need to activate the other items for viewing (right-click Select data)

NOTE! When recording with VCDS - give unique file name for each log. Otherwise the log will be appended to the previous log (thus nothing is lost but can be confusing)