I have a ?96 Buick Regal Gran Sport (3.8L) with 97,000 miles on it. I have been diligent with regular oil changes and preventive maintenance. Up until this past summer, the car has been running great and it has always started on the 1st time after turning the key. However, during the past 4 months, it has failed to start on 3 occasions and my mechanic has been unable to diagnose/repair the problem.
Background: Four years ago my Service Engine Soon light went on (car was running fine) and I took it in and they replaced the EGR Valve ($300) and reset the codes. A week later, the Service Engine Soon light was back on and they told me that I probably had some bad gas or my gas cap was faulty. I switched gas stations and bought a new gas cap. I had the code reset and the light came back on again. Ugh! Since my car was running great, I decided to ignore the warning light. Four years later, in September, 2008, I drove a mile from work to the store and after 15 minutes returned to my car. I turned the key and the engine sputtered/coughed and wouldn?t start. I tried starting the car several times, however, it continued coughing. I left the car for a couple hours and came back to see if it would start. To my amazement, it started right up and ran fine. This same situation has occurred two times since then. If I wait for 15-20 minutes after the problem occurs, the car starts fine. After it happened 4 months ago, I took the car to my mechanic and he focused on the ?Service Engine Soon? light and replaced the Map Sensor ($240) and de-carboned the EGR Valve (the light stayed on). Three months later, I was running errands and after my 4th stop, the car wouldn?t start. I waited 20 minutes and it started. I took it in to my mechanic again and he replaced the EGR valve. The light was out, however, when I went home from work that night, the light came back on again. Two weeks later, the car wouldn?t start again after running errands so we waited 15 minutes and it started up. I took it back to my mechanic and he said the new EGR valve must have been faulty so he replaced it again (no charge). The Service Engine Soon light was off and after driving a mile, I made a 15 minute stop. When I came back to the car it did some mild coughing when I tried to start it so I pressed down the accelerator to rev the engine a bit and it started, even though it was still wheezing a little for about 30 seconds and then it was back to normal. I drove it home with no problem. Two days later, I had a similar occurrence where it started after the third try.
I have no idea what to do at this point and am very frustrated I want to take it back to my mechanic, however, I think he is making repairs and crossing his fingers that it will fix the problem because he isn?t sure what is wrong. The car runs great other than this bizarre problem. I?d like to take it to a different mechanic, however, I don?t want to shell out more money to a mechanic that may not be willing to go the extra mile to get the problem fixed. Since I have been taking my cars to this mechanic for 15 years, I know he will do what it takes to get it fixed without continually charging me, however, I don?t have a lot of confidence that he is doing the necessary research to find the root cause of the problem. I?m open to suggestions.