This article describes how to check and eventually adjust the throttle valves on an M635CSi. This is by no means a straightforward procedure, requiring more than a weekend's hard work and at least some special tools, like a sliding vernier caliper (measuring accuracy of tenths of millimeters or better), a dial gauge able to measure disposition with an accuracy of hundredths of millimeters  plus mounting material, and a vacuum synchrotester (like Carbtune). For an overview of special tools and alternatives, check my other post: BMW special tools This procedure is not un-doable, but if your engine is running fine in idle, and responding nicely to the throttle, it's probably enough to just clean and lubricate the moving parts on the throttle bodies (shaft, bearings, pushing rods). Abbreviations: - TB Throttle Body - ICV Idle Control Valve 1) REMOVE ACCUMULATOR Start off by removing the Accumulator, as described in Overhauling the accumlator on an M635CSI 2) REMOV