It is so frustrating! Mine is still suffering for the pinging issue as well as the low rev stumble during larger throttle opening. There is also usually a noticeable but brief dip in power at around 3000 rpm. Before it used to be also from around 3500 - 4500 rpm. Now I don't know if the new DISA flaps or me cleaning both Vanos solenoids has changed this.
My last DIY a week or so ago was a simple annual oil and filter change (10k km since the last service), but I also decided to replace both engine temperature sensors which involved draining the coolant once it was cool enough of course. So changed the oil and filter first and let the car stand, then drained the coolant. For better access I removed the air box and decided to clean the MAF with some Liqui Moly MAF cleaner - allowed to dry and then reinstalled. New sensors in and added coolant with the bleed screw open. Then ran the coolant purge procedure twice to make sure any and all air was out of the system.
Went for a drive afterwards and all was as before, so no difference. My reasoning for replacing the temperature sensors was that back when the specialist tuner had my car (the same crowd that OP went to that identified the throttle module) they noticed that my car's engine was running colder than it should. At first they suspected the thermostat and then after no return calls and having to physically go to them to get more info, they claimed that they suspected it was more a case of a faulty coolant temperature sensor since the readings they saw were erratic. Of course this was the information that the agents had at the time and simply did nothing about it. Sadly the new sensors have not changed anything so it can only be the thermostat that is not working properly and over-cooling the engine. Hidden menu shows engine temperatures around 79 and 84 degrees Celsius which I gather is roughly 10 - 20 degrees cooler than it should be. So in affect the engine could very well be slightly over-fuelling thinking that the engine is still in the warm up phase.
As for the pinging, my last visit to the agents and taking a workshop foreman to drive my car he suspects that it could be a cam timing issue and the only way to check is to open the engine - valve cover needs to come off and then they can check. Problem is, I am just not willing to foot the bill for this when clearly this should have been done in the first place when the car was indeed still under motorplan! I also cannot believe that an engine with such low mileage (problems started at around 62k km and is now on 69k km) should have problems like this and need this kind of invasive surgery!
My car is completely stock and running the same oil that the agents use which is LL01 5W30 - and my reasoning for annual oil changes is that I can ensure that the engine has fresh oil each year and not only every two years since I don't do very high mileage. Idea being to prevent sludge - from looking in through the oil cap the upper engine seems clean but the oil cap has the sludgy look which seems to be normal (or at least, was like this when I bought the car almost 3 years ago). The old oil and remaining oil in the filter housing seemed pretty clean still, so I reckon with frequent oil service intervals this should help keep clean and possible clean out any early sludge wanting to build up.
But at this stage, I have properly lost interest in the car... I want an E46 M3 now!
