In terms of comparison to gasoline engines where you have the TB and the MAF sensor along with other various sensors and valves (the variable intake piping valve on my Stealth for instance), the OM617 is a very simple engine. Cleaning off the soot from the intake manifold (especially if your EGR valve is still in use), and piping leading up to it are just about all you can do. Air cleaner housing and associated tubage is about it. Disabling the EGR will help a lot in the long run by not recirculating dirty gases and gunking everything up.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth