Some of you may remember the hesitation problem I was having at around 200RPM with my m103 engined Brabus 3.6. While trying to eliminate it I:

Had the ignition system checked on a scope, it was fine - no change
Changed and recalibrated the bosch air flow potentiometer - no change
Had the fuel distributor recalibrated, it was underfuelling - no change
Changed the coolant and ambient air temperature sensors for the KE-Jetronic system - no change
Changed the OVP relay with a new one I had - no change
Replaced the fuel pressure regulator - no change

I rebuilt the engine (bored a new block, new rings etc, had camshaft reprofiled and rockers refaced, valves re-seated etc.) due to excessive oil consumption half hoping that the problem would disappear when it was reassembled, it was still there . My duty cycle was at 40% showing no faults as my car is a non-cat, RUF model. Interestingly, the problem dissappeared when I removed the CTS connector, thus getting rid of the electronic part of the KE system. This makes the system run leaner as the EHA valve does not operate (this confused me as I initially thought that it would revert to a richer mixture). My car failed its MOT due to CO content above 10%! This has now been adjusted down to 1.4%, about right for this car I do believe.

A Brabus plaque for the engine states that ignition code N on the R16 resistor must be used (why?). However, advancing the timing to 2 (sequence is S 2 N 3 4 5 6 7) gets rid of the hesitation problem. Meanwhile at S it feels smother but less powerful hence I have kept it at 2. I have checked the basic cam timing and moved the cam gear to its alternative position to make it line up perfectly with its alignment mark at TDC. I have turned the engine over twice by hand and rechecked this to make sure that the basic timing is spot on. The car does however, feel more aggressive in N once the 2000RPM barrier has been surmounted.

Additionally the car does have a lumpy and low idle at just over 500RPM, sounds and looks like its missing.

Any ideas as to why position 2 "solves" my problem, whatever my problem is? The car used to run perfectly fine in N (a couple of years back now though). BTW I run it on 99RON fuel religiously. Also any idea how long these blocks take to run in?