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Multi bank Widebands - Acceptable AFR difference?

Understanding AFR

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Hi All,

I have just put in a dual wideband setup into my GTR's RB26. The difference between the 2 range from between 3-8% up and down the lower rpms. I have being try trying to fault find but to no avail... Next is to swap injectors over... But before I do, I would like to know if any others have had this issue on the RB26? Or, am I going overkill here?? I know I can set up correction tables etc...

Thanks in advance!

Nick

Why don't you put two bungs into the same exhaust to see if they really are different given the same gas to sample?

Hi David,

I forgot to mention, I swapped the wideband sensors over and the readings are the same. Would say a 3-8% difference is acceptable?

Nick

If I were balancing banks, I usually try to get within 1-2%. But I would accept a larger difference at idle as long as the engine ran smoothly.

Your engine has ITB's right? Is the airflow matched? It may just take a linkage adjustment to bring them closer.

Hi Nick,

What do they do under load? Does the imbalance remain, or does it close up? I have seen this before on multi bank engines where the lambda's where close at idle, but had a variance due to the airflow pattern of the engine at low mass flows, but once the load came up, then they balanced out.

Yes, I re-balanced the ITB's them in accordance with the service manual and the results are the same. I haven't had a chance to properly put load on the engine yet but going from my short term trims, the difference is between 2-3% at very light boost 3000rpm. So yes, it is closing up a little... we shall see what happens!