CEL blinking, rough idle, smoke blowing out exhaust: help!

Black smoke meaning its burning most probable cause of that is a blown head gasket,check your oil depstick for color change if its brown you got it,its also a simp toms of the crankshaft bearing of your car is already wearout also a posible cause of your valve seat,bearings the mechanical parts by the rocker arm assembly.

White smoke is indicative of burning coolant. Gray smoke is burning oil.

Have a compression test done which will often give an indication of evolving head gasket problems. If the coolant level is going down, and there's no obvious leak, its a head gasket.

Ckeck your govenator .

signs of a bad fuel pressure regulator-- the vehicle will run rough, the engine will not start ( usually in the mornings,) many times engine starts but stalls shortly after starting. a bad regulator can result in fouled plugs. replacement is only cure. 1- black soot on plugs-2-black smoke from tailpipe-3- running rough-4- stalling, good-day! repost if need be.

a flashing check engine light (CEL) is a warning to stop driving-one that is on steady (not blinking) means something is wrong, but blinking is BAD-make sure it is completely cooled down, and fill the overflow/surge tank, start it up (use 50/50 antifreeze) and let it idle until the engine temp is all the way up-this can take 10-15 minutes, make sure the heater is on high temp setting and the fan is on-look at the temp gauge if it has one to see if it looks normal. If all looks good, fill the tank to the FULL mark (or a hair above it) and put the tank cap on tight. Drive the car for about 10 minutes, and pay attention to the temp gauge-if it looks good, and the engine is alright, the CEL probably with either not light or will go off by itself.

It is possible you did damage driving it with a flashing CEL, however-if so look for leaks, smoke out of the exhaust, poor running/performance, or more ominous signs of trouble like air bubbles in the overflow tank, oil in the antifreeze of antifreeze in the oil-aluminum engines do NOT tolerate overheating, if you ever see a high temp gauge and/or a flashing CEL-STOP and get it checked out, you will save yourself a lot of money being prudent.

Sorry to inform you of the bad news but the white smoke is engine coolant burning off and the rough running condition is also associated with coolant leaking into the combustion chambers.This will be a head gasket repair, basically a head job where you will need to machine the heads down and install new gaskets from the heads up.Get back to me if you have any more questions, thanks and I hope I could help!!!

2002 a4 try fuel cleaner first, see how that goes after driveing for a while,,,the same goes for the 200 a4,, then we work from there

look for a vacume leak. black smoke means it is running very rich

coolant temperature sensor boken, check and replace if defective.

Assuming that the Smoke is White or Black, You are gonna have to get an Overhaul on that Motor.