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2014 RS5 has a bizarre, random issue, usually when the engine is hot/warm after a drive (never cold or in winter):
Original Issue: Sometimes a slower start—it cranks a bit, occasionally almost stalling. Happens maybe 10% of the time, very random.
The Big Problem (Happened TWICE Now!): After driving, parking for 15-30 mins, and trying to restart, I get a LOUD BANG! Both PCV valve caps blew off, and vacuum lines under the intake manifold popped off.
First time: Led to carbon cleaning and injector cleaning.
Second time (3 weeks later): Same BANG! Still NO current engine codes.
What's Been Done/What's Known:
Car drives and idles perfectly smooth otherwise. No running issues.
Plugs/filters were replaced 6 months ago.
The only old/previous codes P054C00 "Cold Start 'B' camshaft position timing over-advanced" and P000D00 "B Camshaft Position Slow Response (Bank2)"
I'll replace that VTT exhaust bank 2 solenoid but not sure if this will be the end of it
My Mechanic is Stumped. Has ANYONE seen crankcase backpressure like this on restart?
Could this be related to the High-Pressure Fuel Pumps (HPFPs)? If so, why/how would that cause this massive crankcase pressure surge on start-up? Help me out—I'm trying to avoid a costly trip to the dealer with no codes to guide them! Any ideas on this random BANG on restart?
Crazy Audi Engine Mystery! Need Your Expertise!
Any ideas on this random BANG on restart?
