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TOP 5 AUDI REPAIR PROBLEMS
Diverter Valve Failure
Whether your stock diverter valve (DV) is chipped or stock, it's still prone to failure. A common symptom for DV failure is having your car lose a huge amount of boost. You can check it by either a boost gauge or a vag-com (mb 115). Pin-hole DV failures, on the other hand, would typically allow your boost to spike. Another symptom is when you see tears in the DV's diaphragm. One way of addressing this problem is by taking out your stock DV for a new one. On the other hand, you can also upgrade your DV to the Forge DV.
Broken Intake Ducting
It's common for the intake ducting to break off from the stock engine. Worse, it sometimes gets stuck in, or even shredded by, the fan. However, due to its location, the loss in power should be negligible. To solve this, you can simply tape or epoxy the ducting back together. This way, it'll be harder for them to come apart. You can also remove the ducting's top piece. Also, you can go for a new aftermarket intake. If the fan is damaged, however, you may need to replace it.
This usually happens when you're under idle or boost. To check, you might want to look for which cylinder is causing the misfiring. You could also swap coils and/or plugs to see if the misfire follows. If it does, you may want to replace your stock coils and plugs with new ones. If all else fails, you may then have a bad fuel injector. After you've replaced your cylinder, coils, and plugs, be sure to have your car tested before you put it back on the road.
High Pressure Fuel Pump Failure
This problem happens when your high-pressure fuel pump fails to supply enough fuel. It usually happens when your engine is at a low to mid-range RPM (since your engine is cam-driven). When the pump fails, you'd experience a fuel cut-out when you're driving (especially when you're under WOT). If you are using a stock pump, then your dealer should replace this under warranty. On the other hand, if you are chipped, then you can try to put your car back in stock mode by re-installing the original part and see if the fuel cuts stop.
Positive Crankcase Ventilation Failure
The positive crankcase ventilation (PCV) lets gases get sucked from the crankcase to the intake manifold. However, when the PCV fails, it then allows positive pressure (or boost) to go back from the intake manifold and right into the crankcase-thus reversing the process. Usually, you'll see a small drop in boost failure. Oil could also be pushed out through the oil filler cap, and there might be a slight decrease in MPG. To solve this, you can upgrade to the latest PCV valve. However, take note that you should verify the kind of PCV that you have before you start upgrading.