Help! CEL P2A00 after HFC installed
 

I just got my Brek HFC installed last week, after 100mile it throws a P2A00 CEL. (A/F Sensor 1 Bank 1 Circuit range/performance)
I cleaned the code & learned fuel trim. But same CEL came back again after 2 days.
I cleaned MAF, checked intake leak and used soap water method to test the exhaust leak. But I didn’t find any leak at all. The car sound normal except some rattle/hiss under WOT. So, if there was an exhaust leak then it must be very small.

I took some logs, it shows the P2A00 code is caused by different A/F ratio between B1 and B2. My bank 1 is constantly richer than Bank 2 by 0.5-1. (Bank 1 is about 13 and bank 2 is around 14)
The interesting problem is that every time after I cleaned the learned fuel trim. Both banks produced the same A/F but after a while the ECU starts to add A/F adjustment on Bank 1, which makes Bank1 richer and richer. Eventually cause the CEL. The speed of ECU adding A/F adjustment is very quick, 100 mile after reset the A/F adjustment on bank 1 is 0.33 while bank 2 is only -0.002.
I used the same map as before so I don’t think the map will have any problem.

I have an additional Innovate A/F sensor in the drive side (bank 2) of HFC but not in passenger side. The Innovate’s sensor was put in the bung that was on the Brek HFC.

I’m not sure what cause the problem. But my investigation is narrow down to either the additional O2 sensor cause the problem or there was a small exhaust leak that I wasn’t able to find.
Now, My question is which is more likely to cause this type of problem? And is there anything else could cause this type of problem?

My car is 2011 nismo, It’s just under 15k

Did you add an ADDITIONAL bung to one side for your Innovate, or did you just replace the stock one with your Innovate?

Depending on your answer to that question...I may be able to tell you what happened...

well, the the Brek HFC come with 2 bungs on each bank. One for stock which is after CAT and another one is before CAT. Brek put two bolts close those two before CAT O2 bung.

I opened the driver side bolt and put my innovate O2 sensor into there.
Both stock sensors are reinstalled in to after CAT bungs. (which means the driver side HFC has 2 O2 sensor in there and Passenger side only has one)

The bung before CAT is very short. Innovate's O2 sensor is very deep in the pipe. Will that extra resistence of exhaust flow cause my problem?

Forgot to mention, the discrepancy between B1 and B2 is only shown in close loop. Under WOT both banks produce the same A/F. the reading on Innovate gauge in the Bank2 (Leaner side) is absolutely normal.

I just dont understand why would ECU adding fuel onth Bank 1 while the Bank 1 front O2 sensor reading is already too rich?

Is the rear O2 sensor contribute anything to the A/F ratio? or will the rear sensor affect the long term fuel trim? If I disconnect the rear O2 sensor, will that help?

I've had my Berk's (HFC & CBE) installed since last May and have had no issues with CEL. I did use the stock location for the O2 sensors. Good Luck with your situation.

Just for my own edification, what is the Innovate sensor used for?

the innovate sensor is connected to the innovate MTX-L gauge. I would like to keep tracking my A/F ratio from time to time. Becuase I know the stock WB O2 sensor is not as acturate as those aftermarket one. the stock O2 sensors read richer than actual by 0.5 when throttle is applied.

I have the same issue. I just keep resetting it. Going to have my tuner work it out.

Only thing I can guess is that the primary O2 sensor (the one in the collector of the manifold) was damaged during the TP install, causing it to read lean, prompting the ECU to add fuel.

The innovate is mounted in the TP, after the manifold, so even if there was a leak there, it wouldn't change what the ECU sees for fuel management. The post-cat sensors are just to detect catalyst function faults.

Are you able to data-log? Log the MAF voltages for both banks as well as the AFR's for both banks, while in closed loop. See if you see anything funky on the MAF side of things that might explain why it's adding fuel. Only other thing I can think of, since the intakes have to be pulled out for the HFC install, maybe something happened to the MAF sensor on that side.

I used data-logs to compare A/F ratios between Bank1 and Bank2. the data logs show Bank 1 WB A/F is constantly richer than Bank 2 WE A/F. while Bank 1 A/F adj. is around 0.36. So I think ECU must also see Bank 1 is richer.

I think the primary O2 sensor (bank 1 sensor 1) is functioning. because when ECU was reset or WOT, both Bank 1 & 2 WB AFR is nomal. However, after cuple mile bank 1 become richer and richer because ECU adding fuel on Bank 1. Voltage on both sensors are correspending with the AFR and changing rapidly.

uprev only shows one combined MAF and voltage. At least my uprev does not have any bank 1 & bank 2 option for MAF. I checked my intake 3 times already and I also tried to replaced the stock tube by Z1 post MAF tube. but the problem is still there.

Hmm try and log using Osiris instead of Cipher. That should let you see both MAFs, I think.