Hello, long time I've encountered this problem, so I thought I should ask for help and ideas. My car is a 2001 320Ci with the m54b22 engine that has the EU2 tune (post cat sensors deleted). The problem is I have negative STFTs all the time, except for when really stepping on it. Strange thing is that my LTFTs are perfectly normal. Maintenance to the car is quite thorough.
Both pre-cat O2 sensors were changed with new Bosch, fuel pump with Siemens VDO, fuel filter with Mann, boots, DISA o-ring changed, DISA rebuilt, VCG changed, car runs fine, no codes. I cannot find any vacuum leaks. The only symptom I have is that if I floor it from low RPM in 3rd or 4th gear, it sometimes bogs, like cutting throttle. MAF sensor is original, but car has 100k miles and it does the same even with MAF sensor unplugged. I checked fuel pressure and it starts at 49 PSI, then drops to 30 PSI. I suspect that's a problem, but gauge drops even if I move it so i don’t know. Also, I checked injectors for dripping, I got none.
It had negative STFTs even before the fuel pump and fuel filter change.
I swapped injectors of bank 2 (which seems to be the problematic bank), with some used ones I had, but STFTs remain negative most of the time. Car starts and runs fine, I maybe have a vacuum leak somewhere but I can't find it. I smoke tested it, and nothing, I also pressurized the intake, as much as I could with my mouth though, it holds pressure.
I have attached a link to some OBD fusion logs, per jjoj’s instructions.
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Both pre-cat O2 sensors were changed with new Bosch, fuel pump with Siemens VDO, fuel filter with Mann, boots, DISA o-ring changed, DISA rebuilt, VCG changed, car runs fine, no codes. I cannot find any vacuum leaks. The only symptom I have is that if I floor it from low RPM in 3rd or 4th gear, it sometimes bogs, like cutting throttle. MAF sensor is original, but car has 100k miles and it does the same even with MAF sensor unplugged. I checked fuel pressure and it starts at 49 PSI, then drops to 30 PSI. I suspect that's a problem, but gauge drops even if I move it so i don’t know. Also, I checked injectors for dripping, I got none.
It had negative STFTs even before the fuel pump and fuel filter change.
I swapped injectors of bank 2 (which seems to be the problematic bank), with some used ones I had, but STFTs remain negative most of the time. Car starts and runs fine, I maybe have a vacuum leak somewhere but I can't find it. I smoke tested it, and nothing, I also pressurized the intake, as much as I could with my mouth though, it holds pressure.
I have attached a link to some OBD fusion logs, per jjoj’s instructions.