I had a problem with erratic idle on a VAG petrol engine and that turned out to be emulsified oil on the inlets that prevented butterflies from closing properly. The engine management system then got its knickers in a twist and couldn't properly regulate the idle speed... in general it was too low.
The solution - dismantle the inlet system, clean everything and reassemble. Then reset the engine management system idle parameters [I needed VCDS VAG software to do this]. Everything perfect afterwards.
The reason why emulsified oil got into the inlet system is because modern engines scavange oil vapor from the crankcase to keep emissions low. That's fine on a new engine, but as the engine ages and crankcase pressure becomes more of an issue, more than just oil vapor gets scavanged.
This may not be relevant to your case Roadrat, but I guess it may be helpful if anyone suffers a similar problem to mine in the future.
|
|