AFR difference between the banks

Megan370z

just to give a sample example on this issue with Bank 1 & 2 not being equal.

adjust the whole bank that is leaner to the other side.
on the table it would be like
1:100%
2:105%
3:100%
4:105%
5:100%
6:105%


as for tuning for each cylinder.
I cant help you on this. I have a theory but I wont go on that subject.

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Mitco39

I spent a good part of 5 hours logging my car today and noticed a few things. Bank 1 would consistently run 0.5-1AFR richer than bank 2. The kicker is the ECU was commanding bank one to run at ~115% which was clearly causing the rich issue. Bank 2 trims would sit at about 97-104%.

Those trim values posted here are only good for open loop conditions. Under closed looped the ECU is going to do everything it can to make each bank meet the target afr.

That being said the ECU is for whatever reason commanding one bank to run richer than the target. I have done some research on this tonight and it looks like with a CAT delete guys have been running into issues where if they reset the trims its dam near perfect, however after a bit one of the banks will richen up on its own as the trims come back into play. Some of the 350Z guys have just unplugged the post cat 02s as it seems like the ECU does listen somewhat to these cats as well.

I have tried everything to try and dial these values in with all 4 cats connected to the car. No luck, eventually in closed loop the car will deviate. While on the road for awhile one bank afr will read 14.5-14.9 just bouncing around slightly, the other bank afr reads 13.6-14.0. My wideband which is post turbo after the exhaust gasses mix sits at about 14.1-14.3.

Has anyone had this issue? I guess the next thing im going to try is unplugging the 2 post cat 02s. I just hope this doesnt put the computer into a permanent open loop state.

Any suggestions would be appreciated.

Thanks

Mitch

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hc_416

I actually have that same problem thou it is on a G37. I found out by a Uprev e-tune. Randy said to look for a air leak that was the size of a pin hole...

As for the two problems I noticed the first was at idle. I need to idle around 95-105% on both banks. Bank one idles correct, but bank two will idle between 90-115%.

The second problem is when I am WOT I have deavations of 1.0 AFR on bank 2 from bank one. If bank 1 was 11.00 bank 2 would be 11.80-12.00.

The only thing I found that temp "fixed" it was tighten up the exhaust, but when it came back I had the same problem on both banks now....

I believe the problem is in the exhaust somewhere. If it is in the seals, blown out hfc or broken shorty's I am not sure. My next plan of attack is to go to LTH and get rid of the seal between the shorty's and HFC. While doing that I will look at the 02 sensors and other connections.

Well I hope I could help and subbed for info. GL