After a 160,000 miles of excellent care and maintence, PepBoys has successfully managed to cause some damage to my 1991 Mazda Miata, and are not able to pinpoint it. They put a bad part in during a simple repair (valve cover gasket) which escalated into hesitation during acceleration, loud rattling and hard to start. There was oil sludge all over everything under the hood. It really was a mess. It took about a month for the car to start acting up after the repair (granted I only drove the car 120 miles in that month).

After diagnosing the car, they have replaced the bad valve cover gasket, sparkplugs and wires, camshaft position sensor and coil and continue to give it back to me in the same condition. I don't know what else it could possibly be, just that my car had no problems until after the oil change/valve cover gasket repair. What else could the bad part have damaged?

I found this forum trying to diagnose the problem myself, before I take the car back a fourth, or is it fifth day?

Any advice is greatly appreciated.

 

If you pull the spark plug boots, check for oil pooling in the spark plug reservoir. Also, in the diagnostic center plug (on the US driver's side), use a paper clip and jump GND and TEN terminals. Turn the ignition on, but do not start. If you have any codes, the Check Engine light will flash with codes. Count the number of short and long codes between pauses. What do you get?--you can then go to a service manual and review. If you do not have one, just report it here. Also is the condition the same when cold and hot?