I got a 05 audi a4 1.8 turbo the check engine light has always been on and hasn't caused problems but now it flashes when the car idles and it sounds like a little miss also ther is smoke coming out my exaust...when I hooked it up to code reader it would connect and communicate but once it got to transmission it would stop communication and say turn key off can anyone tell me what's goin on?

 

Vibration or shaking may be caused by misfires, poor fuel pressure, or faulty spark plugs. You should also know that a defective idle air control valve might make the engine idle drop significantly. ... Another issue that may cause check engine lightblinking car shaking is a broken engine mount.