Quote:
Originally Posted by tchowe
When I got there they had the intake all taken apart. Said the engine itself is fine. They're cleaning oil out of the intake manifold and box, cleaning out the PCV, and replacing some other parts. When I asked about the transmission hesitating the mechanic said it was likely oil on the airflow sensor throwing it off. Said he's also going to treat the system with sea foam to burn out any excess oil.
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I think your engine sucked up the foamy oil through the PCV and screwed up the A/F mixture so much it either knocked, misfired, or some combination of similar events. This threw your car into limp mode. The A8 probably can't go above 3rd gear in limp mode, and you interpreted the sudden downshift as slipping. It all probably happened pretty fast
The PCV tube lets crankcase gases re-enter at the intake manifold. Since that is past the MAF and the throttle body, I think those parts are unaffected. Sounds like they are cleaning the intake manifold and PCV vent as well as the valve (they should probably just replace the valve), and maybe giving you new plugs. Depends how the plugs look when they pull them to foam the combustion chambers. Unless the plugs are an oily disaster they will probably assume the injectors are fine, reassemble, and test drive the car.
Your car basically choked on oil and stopped. A good thing because it prevented more extensive damage like fouling the O2 sensors and cat. I think the less they take apart the better.
You should ask what they plan to do about the oil. Just drain it to proper level, or redo the whole oil change?