I greatly enjoyed the recently posted Schrodingers Box youtube tutorials on fuel trim diagnosis. My current situation is baffling me however so I'll throw it out to all of you.
I have a CEL with a single code P1130 (lean on bank 2). It first came on a month ago but cleared itself after a few days. It just came back on this week, same code.
I have done a bunch of data logging using a bluetooth OBDII and DashCommand. The only thing that stands out are consistently high LTFT values, 8-11% on bank 1 and 6-9% on bank 2. The STFT values look normal to me, fluctuating mostly in the +-5% range in response to what appear normal O2 sensor traces.
In my few hours of logging the LTFT values vary very little, but do seem to very slowly (over tens of minutes) decrease while driving at speed.
However every so often they spike to like 20%, but sharply and only for a few seconds, seemingly in response to opening the throttle and corresponding high MAF rates.
The image shows about 3 1/2 minutes of data. LTFT and STFT traces in the upper panel, Speed, RPM and MAF in the lower pane.
So what is your diagnosis? Are these spikes triggering the CEL?
The stock answer for this CEL code is intake leak and I do plan to bring it into the shop next week for a thorough diagnostic, smoke test etc. to resolve this. I didn't expect the data to look like this however, shouldn't an intake leak result in lower LTFTs when accelerating and cruising at speed? Why don't these LTFT numbers change much at all, is this a feature of Porsche adaptations unlike other cars like in that guys videos?
Cheers, Richard
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