Cleaning B57 intake manifold

[Greenfingers]

Having done this job on my three previous BMWs (with M57 and N57 engines), I know how gunked up the intake system can get. Cleaning the throttle body, intake manifold and egr pipe resulted in noticeably improved mpg and responsiveness in all three cases, so I am planning to do the same for my G31.

There seem to be loads of tutorials for the previous engines, but I'm struggling to find a good guide for the B57. It looks like a fairly straightforward job, so the scarcity of information on the web is surprising. Granted, many of the newer models will have been maintained by dealers or garages and not yet fallen into the hands of DIYers, but there must be plenty of high mileage cars out there now. One thing thas does seem conspicuous is wear to the swirl flap actuator shaft, causing implausibility readings from the position sensor and even air leaking past the seal at the actuator end. BMW's answer is to replace the manifold, but that is taking a wear and tear approach to something that shouldn't be happening and will likely need doing multiple times if the car is driven to, say 200k miles. I intend to remove the flaps and hopefully the shaft as well, if I can find a way to seal the exit point near the actuator.

My guess is that the biggest restriction to air entering the engine is likely to be at the end of the EGR pipe, at the junction just after the throttle body. This is the first thing I want to check, but I'm not sure if the pipe can be removed without pulling out the whole intake manifold.

Can anyone advise?

[Peternette]

Hi Greenfingers,

I am about to go the same route - did you find any answers or can you advise how you got on please?

Thanks,

Peter