Millenia S hard start after Dealership Service
 

We have a 2001 Mazda Millenia S. We bought it new, it is just coming up on 100K miles. We took the car to the local dealership where we bought the car. for the big service (timing belt, water pump, seals, spark plugs, and other recommended service items), about $2300 worth of work. About a week later the car begin to have trouble starting when cold. It's getting worse, and the dealership just shrugged their shoulders and said the car started fine for them when we brought it back for them to check out. No codes, no CEL. The car has always started and run perfectly until the service was performed. The car starts fine when warm. The car passes the fuel pressure test described in the mazda manual.

Any words of wisdom out there to help us find the problem?

Thanks.

Have you left it overnight with the dealership for them to carry out a cold start themselves?

Yes, we have. The dealer had the car again a week after the major service event (timing belts, etc). They reported the car started fine for them. Today is January 30, and the car is now back at the dealership. We'll see how it goes. In the interim, I replaced a broken vacuum tee in the intake manifold vacuum system, and did a bunch of troubleshooting. Mazda has a troubleshooting guide that includes a line item for cold start problems. The one thing I can't test is the ECM-related inputs - the dealer has a special test instrument that taps into the ECM wiring.