What might these BEW Log Group 013/023 mean?

[Wilkins]

I'm wondering if anyone thinks any issues are indicated by these logs. Car starts well, but runs a wee bit rougher when first started than when fully warm. For the last 3-4 years it seems to me that it has been a bit rough at very low revs either on overrun or under power, at least compared to my CR. Overall the car runs pretty well with good power, quite smooth over 1800-2000 rpm. I think the tandem pump gasket is leaking and the exhaust might have a small leak in the flex pipe - it is noisy when cold but quiet once warm. I've been trying to figure out if anything is going on for a few years, since it is not as smooth as it once was, have found and fixed a number of small issues but I still think something else is going on.


I have not looked at the cam yet this year but last year it seemed ok



It seems to be cylinder 1 that is moving around erratically, I tried to indicate that the log plotting application put the scale for cyl 1 on the right while the other three cylinders have the scale on the left.


Click on the photos for full size images








Any thoughts?

 

[Rembrant]

If I understand your graph correctly, your numbers are, roughly:

Cyl 1: -0.9 to -1.0
Cyl 2: -0.30
Cyl 3: +0.35
Cyl 4: +0.90

I'm new to the PD TDI world, but from my reading on here, the correct healthy range for those numbers is between -0.5 and +0.5 at operating temperature. Somebody can correct me if I'm wrong.

 

[Wilkins]

Yes.
Cyl 1 is -0.94 to -0.96 mostly with bumps to -0.92 and -0.99
Cyl 2 is -0.28 to -0.31
Cyl 3 is 0.35 mostly with variations to 0.38 and 0.33
Cyl 4 is 0.89 mostly with variations to 0.87 and 0.89

It's a bit hard to tell because the scale is different between Cyl 1 and Cyls 2,3,4. I have done a bit more research since I posted initially and I'm beginning to think these numbers are pretty meaningless. Looking back at some of the historical data I have I see

June 2015 I was seeing -0.48, -0.42, 0.31, 0.61
Sept 2015 I had -0.07, 0.14, 0.09, 0.09

I'm pretty sure the September numbers were after a diesel purge application and after fixing a vacuum leak in the fuel return thermovalve. If I recall correctly replacing the thermovalve had a much bigger return than the purge. I also have read that +/- 2.0 is a reasonable range.

I'm planning to invest some time and money in the car and before I do so I want to at least know what problems might be there.