Well so I know what it isn't now. It is not a vacuum leak, I did another smoke test to verify. It isn't fuel pressure, it has been reading perfectly since replacing the filter/regulator. It isn't the MAF since I did a swap an it had no effect (the original was reinstalled). The next step is the upstream O2 sensor. I notice on my scan tool the voltage does not seem to fluctuate. I have one on order and will know within this next week.
So, how are your fuel trims, when shown on your scan gauge (live data); since, the fuel filter/fuel pressure regulator replacement?
As to obdeleven; i have not used obdeleven, i recommend using their tech support and research discussion forums for help, with its use. I would think, your questions have already been asked, answered there and others have experienced, the exact same issues as you.
There are times that the readings are right in scale where they're supposed to be then all of a sudden it will shoot to 25. Then maybe after a while it'll all the sudden go back to normal. I've tried to see if I could find a way of triggering while driving but it's very random. If I drive for a length of time then the transmission seems to have some issues with shifting in the first couple gears. If I turn it off and let it sit for a bit it works just fine again. This is why I'm starting to question the o2 sensor. Thing is every OBD program that I have only monitors the voltage of the second o2 sensor and not the first. It only shows a wide range. Kind of difficult then to see if it is fluctuating like it's supposed to. Luckily either sensor is not that hard to get to. With obd11 I finally figured out the channels but can't seem to get live data. It always says unavailable. The pictures below detail out what it is that I can read on this particular car. I know this is not the obd11 screens but the options are still the same.
Here is a video, showing obdeleven use and the tech viewing live data, accessing channel 32 (long term) and 33 (short term) fuel trim. You might see; if this works for you, report back with your results
I did exactly what he does. It connects and scans. When I select live data, enter 32, 33 or any channel it says 'Not available'. Very frustrating. I can see all of it with a different app (see picture). I have a email into OBD11 on this issue.
In general, an out-of-spec value in the first field (Additive) indicates a vacuum leak since it is mostly present at idle, when vacuum is highest. An out-of-spec value in the second field (Multiplicative) indicates a fault at higher RPM, and may point to a faulty MAF.
I had not looked or considered the vacuum pump. I did watch a great video on it. I would think if it was leaking vacuum the smoke test I did would have revealed it. I did spend some time under the car and noticed the pan of the engine had a light coating of oil. I wiped everything clean to reveal the source. The O2 sensor arrives tomorrow, so with fingers crossed it will be the issue. If not then it is one more thing to cross off the list. Part of the rattle sound I recorded turned out to be the scuff tray being loose. Although there still is a rattle sound, I am concerned because it may be coming from the catalytic converter. Hard to believe the cat could be bad already on a engine with only 56K on it. Well one thing at a time.
So it looks like the O2 sensor did the trick.......so far. My short trim never got above 10%. I didn't get to drive it very far, limited on time. It was an easy swap out, maybe 15 minutes. I'll keep you posted.
Finally, you are making solid progress (!); when getting my 1.8T running correctly, I found it was a wide range of ignition and fuel related parts, that were old, not working at their top of efficiency, which can eventually be beyond the computers ability to compensate for. These parts, wear out over time and your performance suffers; until, they are beyond their ability to perform their job, a cumulative effect, eventually causing fuel trims to be way out of balance, out of spec.
These modern vehicles, area pretty amazing; as they, compensate for so many things and keep the car running, while in the past, the points/distributor, carburetor era cars, would just stop running or run so badly, they were unusable! While, we all seem to complain about these newer cars and they have their problems; the reduction in maintenance and overall reliability, can be much greater!
PS: when, i replace my last 02 sensor; I noticed, a improvement in power, increase in gas milage, starting easier, acceleration response and just overall drivability, was MUCH improved.
Good work and solid troubleshooting! As you go through all the parts (test, confirm, replace); that make up the ignition, fuel delivery system; they all add up, to a very good running engine! After 15 to 20 years; most VW's I see are not running correctly but just keep getting driven, as these modern computers, help to keep 'em running!
Also, if hasn't been done recently; is remove the throttle body, replace the gasket, throughly clean, the butterfly valve and do a throttle body alignment, using vcds. This can help, increase the accuracy of the air fuel mixture and possibly lower the fuel trim numbers.
Well the engine issues are officially over. She's purring like a kitten now and got all the correct readings. Now I got to figure out this damn transmission that when it gets warm shifts rough in the first few gears.