Oxygen sensing range 1 values way off

Dear all, in May I had a post here regarding slightly increased sensing range 1 values (approx 0.3 instead 0). It turned out to be the AOS, after it was exchanged the values were fine. Now approx 6 month later I recorded my DME values again and noticed somthing strange. Yesterday the sensing range 1 values were way way off: Oxygen sensing, cylinders 1-3 ----- 1 Oxygen sensor voltage ahead of catalyst converter ----- 0.44V Range 1 Cylinder 1-3(TRA) ----- 4.03 Range 2 Cylinder 1-3(FRA) ----- 1.00 Oxygen sensing, cylinders 4-6 ----- 1 Oxygen sensor voltage ahead of catalyst converter, BANK 2 ----- 0.44V Range 1 Cylinder 4-6(TRA2) ----- 4.00 Range 2 Cylinder 4-6(FRA2) ----- 0.98 Today I recorded them again and it looked like this: Oxygen sensing, cylinders 1-3 ----- 1.02 Oxygen sensor voltage ahead of catalyst converter ----- 0.76V Range 1 Cylinder 1-3(TRA) ----- 0 Range 2 Cylinder 1-3(FRA) ----- 1.00 Oxygen sensing, cylinders 4-6 ----- 1.02 Oxygen sensor voltage ahead of catalyst converter, BANK 2 ----- 0.76V Range 1 Cylinder 4-6(TRA2) ----- 4.03 Range 2 Cylinder 4-6(FRA2) ----- 0.98 The range one values are 0 and 4.03 and they seem to be stuck.The range 2 values fluctuate slightly while driving, Range 1 has always the same strange values. In addition, the air mass readings are very high; e.g.: Air mass ----- 7104kg/h But I am unsure if this is actually the mass air flow value (which afaik should be about 17 kg/h). Maybe there is also a unit glitch or something with my scanner, an iCarsoft POR V2.0. The car drives fine, did not notice any issues at all. There is also no fault code. I did not do any DME recordings between may and now, so I dont know how long the issue is already there. Anybody got an idea what could this be? A sensor failure/issue? Best wishes, Wintermute I post a complete DME reading here, maybe some clues can be found: A/C request ----- Closed Disturbance switch ----- Closed Fuel reserve signal ----- Off Full load recognition ----- Closed Idle recognition ----- Closed Reference mark signal ----- Not present Start enable switch ----- Open Transmisson coding ----- Manual transmission coding Oxygen sensing, cylinders 1-3 ----- 0.97 Oxygen sensor voltage ahead of catalyst converter ----- 0.81V Range 1 Cylinder 1-3(TRA) ----- 0 Range 2 Cylinder 1-3(FRA) ----- 1.00 Oxygen sensing, cylinders 4-6 ----- 1 Oxygen sensor voltage ahead of catalyst converter, BANK 2 ----- 0.01V Range 1 Cylinder 4-6(TRA2) ----- 4.03 Range 2 Cylinder 4-6(FRA2) ----- 0.98 Air mass ----- 9984.75kg/h Ambient pressure ----- 845mbar ECTS ----- 84�C Engine compartment temperature ----- 28.50�C Exhaust temperature after catalytic converter ----- 512�C Hot film MAF ----- 1.80V IATS ----- 17.25�C Ignition timing ----- 36.75� CRK Injection time ----- 6.67ms Load signal ----- 3.60ms Oil temperature ----- 88.50�C Rpm ----- 3320rpm Specified air adaptation ----- 0kg/h Specified air mass ----- 39kg/h Speed ----- 65km/h Throttle plate angle ----- 5.86% Voltage ----- 13.21V Camshaft position 1 deviation ----- 3� CRK HO2S heating Resistor ahead of catalyst converter ----- 3.13Ohm Learn Progress, sensor Wheel adaptation ----- 0.00 Misfire detection ----- Not Active Rough running ----- 0L/s� Rough-running threshold ----- 13.20L/s� Segment(A) ----- 0.10 Segment(B) ----- 0.10 - - - - - - - - - - - - - - - - - -

When I read the air mass with the standard obd scan I get e.g. 6 g/s at 810 rpm which seems ok. The Porsche specific scan provides the strange readings mentioned in my initial post. Maybe rather an issue with my scanner and not with the MAF. At any rate, the oxygen sensing range values remain off. At the moment it is only bank 2 at 4.03, bank 1 is 0 (but not sure if trustworthy because it previously was also at 4). Best Wintermute

What I found out regarding the TRA and FRA values is that they are the long term fuel trim. TRA is relevant for idle and low rev range (I read that it is up to 1700 rpm), after TRA comes FRAU (U stands for "untere" = lower) and finally for high rev there is FRAO (O stands for "Obere" = upper). TRA is ideally 0, FRA is ideally 1. If the value is below the ideal value it means the car is found to run too rich in the respective range and fuel is taken away. If the value is above the ideal it means the car is found to run too lean and fuel is added. TRA is also known as RKAT (Relative Kraftstoffmenge (fuel amount) Additive and Time). RKAT is an additive value meaning it is added to the injection time to correct dominant deviation from the ideal mixture. An RKAT of 2.0% would mean that at relative engine load of 20% needs a relative fuel amount of 22% (+2.0% from RKAT). In my case there could be an intake air leak making the mixture too lean and thus TRA is compensating. Strange that my bank 1 TRA was also 4 in the beginning and now it is 0. I found an advanced technical info from Porsche on TRA and FRA, will look a bit deeper into it and post here again in case I find something enlightening.

Thank you for posting your findings. Let us know what you discover.

Thank you for posting. I too have been tracking down some possible fuel issues for awhile and I�m starting to suspect that it could be a weak fuel pump.

Quotes source post: 17771665

Hm, that probably could also be a reason for a high TRA or FRA value. I used the opportunity to order a new intake hose, when it arrives I will also have a look on the rest of the intake system. Dont have a "smoke device" yet though, might try with starter spray.

Still got these strange 4.x TRA values. No fault codes though and no issues with idle or the likes (at least nothing I would notice). In part I thought it might be an issue with my reader, i.e. giving a wrong value. But it showed close to 0 values after I got a new AOS and also slightly off readings like 0,3 with the broken AOS. I finally did a smoke test now and did not find anything big, but I saw 3 smaller leaks. One at the idle ctrl valve (very minor), one at the bearings of the flap in the intake manifold (super minor, only faint smoke) and one at the valve for the secondary air system (not huge, but the biggest of the three). On the pictures I indicated where the smoke seemed to originate (but I took the pictures only afterwards unfortunately). Anybody knows if any of these requires action? Dont htink this is causing my TRA "issue"? Best wishes and thanks Wintermute Leak at valve Leak at bearing leak at idle control valve

Any vacuum leaks require attention. They will all have an impact on your DME. For the intake resonator tube leak, search for posts made by my username. I posted a super easy, cheap, effective fix for it about a year or so ago. For the ICV, you could consider putting some silicone caulk over the crack in the plastic housing of the ICV. Otherwise you�ll likely need to replace it, and they aren�t cheap.

Your " leak at bearing " get a rubber cap that fits snug over the perimeter . A small amount of sealant at the base before sliding on the cap will solve that one .

Hah, excellent, also found the pic of the cap @islaTurbine posted. Will search for something that fits. The icv is indeed quite expensive, will investigate closer where exactly the leak is and try to close it. The valve of the secondary air system is not so expensive, could just get a new one. Thanks for the answers!