Audi A4 1.8T missing

You will need to read engine management light with obd reader it will then give you the error code as to the problem

probably Idle air control valve or EGR. under the dash there is a diagnostic port! with key off bridge terminal A & B turn key to on position (do not start) this will flash any trouble codes VIA the check engine light the first blink(s) are confirmation. then count blinks EXP,*** **= 32 , ***** ***= 53 , ** ********= 28... then just google GM OBD1 trouble codes and see what the problem is .

minor engine missing & vibration on slow speed

should be in your owners manual if you have one. or there should be an options menu through the switch in the instrumnet cluster or through the I-drive if you have one

Sounds like the Catalytic converter needs to be looked at or replaced.

Probably a loose wheel sensor connection (or the rubber boot on the sensor may be damaged/letting in water)

yes you must remove the gas with a special machine ,and flywheel bolt is about 8 bolts normally .

i had a similar problem it turned out to be a neuteral selecter sensor located on the gear box

ELECTRONIC STABILITY PROGRAM ( ESP) LIGHT FLASHES TO INDICATE UNSTABLE DRIVING CONDITIONS....WHICH WILL ALSO COME ON IF YOUR ENGINE IS MISFIRES.. CHECK THE COILS AND SPARK PLUGS FIRST THEN GO FOR FUEL..INJECTORS...FUEL FILTER CHOKED..HOPE I WAS OF SOME HELP TO YOU..

There is a few things to do check the door switches that control dome lights, check wire down by the skid plate when you get oil changed there is a sensor for the starter there if it is stolen the alarm will go off or just take a BAT and BEAT the living **** out of your horn and call it good like I am going to. I hope this helped or will help I recommend an aluminum bat vrs. wood