As soon I receive some significant information about specific nuances, what would be worth to know for all users of these specific engines, I try to publish it in blog ASAP.

Thank you to everyone, who shares with information – both from me and from other bimmerprofs readers.


Just now I got information, that one user of N43/N53 didn’t receive the label of TI, because during the performance test of the engine (connecting the diagnostics computer) has been detected, that fuel correction integrators (STFT) are with fixed – zero value.


This situation (STFT with zero value) is in the case when the engine works in Homogeneous lean and/or Stratified charge (with Lambda 1.4 .. 4.0). If the engine works in Homogeneous lean and Stratified charge, LTFT and integrators (STFT) are not used!

In Homogeneous mode (mode of a “regular” engine) the fuel mixture is “corrected”, using LTFT and STFT (integrators), because the proportion air/fuel has to be maintained correctly. At Homogeneous lean and Stratified charge (specific modes exactly for N43/N53 series engines):

  • the amount of fuel (not using LTFT and STFT) defines the required torque;
  • fuel proportion (Lambda 1.4 .. 4.0) is adjusted, changing the opening of the throttle.


In Homogeneous lean and Stratified charge modes, it’s not necessary to maintain exact proportion of air/fuel (fluctuation of +/-10 .. 20 % is completely acceptable), so the LTFT and STFT are not used.

True though,


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Test instructions for the exhaust-gas (emissions) test on BMW vehicles with petrol engines

BMW vehicles as from the model year 1968, MINI as from R50 and Rolls-Royce as from RR01


nothing is mentioned about the performance of integrators because such technical nuance in no way applies to measurements of exhaust gasses. Or, simply saying – if the exhaust gasses are in allowed range (also Lambda: 1.0 .. 4.0, according to the document, mentioned above), no additional controls won’t be required.


If you have problems with successful passing of TI, I invite you to print out the document, mentioned before (it’s available on the Internet) and insist, that for these engines Lambda can be increased to 4.0 both in idle and in partial load mode.


Control of integrators is unjustified and illogical; if the Inspector mentioned “non-moving” integrators as an argument, that the engine doesn’t performs correctly, object!