Hello all, hoping someone can help!
I’ve searched through every N54 forum or community for my issue but really nothing conclusive or logical
To keep it simple, my AFR1 and AFR2 readings aren’t the same on deceleration. AFR2 will go full lean (234) relatively quickly but my AFR1 will lag behind for quite a few seconds around the 180-210 figure.
So the first suspicion would be injectors, but I’ve changed them 6 months ago so it felt unlikely. I’ve let the car sit overnight and checked the plugs and only cylinder 2 plug was somewhat black and fouled on the threads but not the electrode. I’ve swapped injector on cylinder 2 with cylinder 4 on bank 2 with no change. I could swap the other injectors but I highly doubt this is the issue. For all the other similar threads posted it rarely ended up being the injectors.
My O2 readings both pre and post cats look good on INPA with symmetrical voltage readings and error free testing. My LTFTs look within range (10% max difference between both banks). Car actually runs fine with no errors.
The confusing part is that I’ve checked three logs done 1) pre new injectors 2) after new injectors 3) recently and this delta in AFR readings on deceleration is consistent all the time. In 1) the injectors actually where leaking with a lot of misfire codes and obvious fuel leak into the exhaust.
Afaik AFR readings are measured by O2 sensors, I’ve ordered a new pre and post cat set to see if maybe they’re faulty. Clearing lambda adaptions on MHD did nothing for me. I suspect this won’t change much.
Alternatively, one could assume faulty valve seals but compression on all cylinders is 175psi, so I doubt there’s an oil leak in here.
One guy fixed it by replacing a cracked valve cover gasket, but after inspection I see no seepage. Coil and plug holes look ok except a bit of carbon sediment at the bottom which I believe is normal. Even the injector holes are clean and look round, so I doubt there’s any issue here. Unless there’s an internal leak in the VCG I’m not seeing, but would like to hear some suggestions on this. Car has 60.000km 2010 Z4, so low end of mileage doesn’t make this very probable.
Another guy fixed it by changing faulty turbos, but his were leaking and had only issue when getting into boost. I have a set of hybrids to install due to turbo siren on stockers, but even here, I don’t have high hopes that this will fix it.
Here’s a log link from a highway run https://datazap.me/u/davgia/ggh?log=0&data=13-14-20
I rarely tend to post unless really necessary but I’ve exhausted reading material on the matter..
Any input is absolutely appreciated,
Cheers,
Dave
I’ve searched through every N54 forum or community for my issue but really nothing conclusive or logical
To keep it simple, my AFR1 and AFR2 readings aren’t the same on deceleration. AFR2 will go full lean (234) relatively quickly but my AFR1 will lag behind for quite a few seconds around the 180-210 figure.
So the first suspicion would be injectors, but I’ve changed them 6 months ago so it felt unlikely. I’ve let the car sit overnight and checked the plugs and only cylinder 2 plug was somewhat black and fouled on the threads but not the electrode. I’ve swapped injector on cylinder 2 with cylinder 4 on bank 2 with no change. I could swap the other injectors but I highly doubt this is the issue. For all the other similar threads posted it rarely ended up being the injectors.
My O2 readings both pre and post cats look good on INPA with symmetrical voltage readings and error free testing. My LTFTs look within range (10% max difference between both banks). Car actually runs fine with no errors.
The confusing part is that I’ve checked three logs done 1) pre new injectors 2) after new injectors 3) recently and this delta in AFR readings on deceleration is consistent all the time. In 1) the injectors actually where leaking with a lot of misfire codes and obvious fuel leak into the exhaust.
Afaik AFR readings are measured by O2 sensors, I’ve ordered a new pre and post cat set to see if maybe they’re faulty. Clearing lambda adaptions on MHD did nothing for me. I suspect this won’t change much.
Alternatively, one could assume faulty valve seals but compression on all cylinders is 175psi, so I doubt there’s an oil leak in here.
One guy fixed it by replacing a cracked valve cover gasket, but after inspection I see no seepage. Coil and plug holes look ok except a bit of carbon sediment at the bottom which I believe is normal. Even the injector holes are clean and look round, so I doubt there’s any issue here. Unless there’s an internal leak in the VCG I’m not seeing, but would like to hear some suggestions on this. Car has 60.000km 2010 Z4, so low end of mileage doesn’t make this very probable.
Another guy fixed it by changing faulty turbos, but his were leaking and had only issue when getting into boost. I have a set of hybrids to install due to turbo siren on stockers, but even here, I don’t have high hopes that this will fix it.
Here’s a log link from a highway run https://datazap.me/u/davgia/ggh?log=0&data=13-14-20
I rarely tend to post unless really necessary but I’ve exhausted reading material on the matter..
Any input is absolutely appreciated,
Cheers,
Dave