Kel

Engine wouldn't start. Dealer said carbon buildup. What causes this???

James R.

Running the car for excessively short periods of time...like a minute then shutting it off.

Allowing the car to idle till it comes to temp in the morning...seems like a good idea but it can actually foul your plugs cause the idle map is very very rich to promote faster heat up and reduce the chance of stalling while idling cold, this rich condition can soot the plugs up.

Using crappy gas...this one's kinda questionable though.

I'd try and run some injector cleaner type stuff from time to time, I personally use the Red Line fuel system cleaner...it's cheap and you can buy it at Pep Boys...it's pretty good stuff.

Regards,

James R.

99 1.8TMS (Neuspeed K04, K&N Filter, S4 Wheel Well Liner Mod, Remus Exhaust, Neuspeed Sport Springs, Neuspeed Front Anti Sway, Bilstein Sport Shocks, Brembo Rotors, Mintex Red Box, Ronal R-7's 17" Bridgestone S02 PP, Smartire (neat gimmick), Euro Corners, Clear Sides, Full Tint)

eharleq

Running lower octane gas often has fewer detergents and can have the advance cut back. The extra cold start injector is the source of deposits too. Audi even has a brochure on needing the run cleaner on the 5 valve motor.