QuestionHI, I HAVE A 1999 CAD.SEVILLE STS 4.6L (9) ENG. MY PROBLEMS ARE SOMETIMES WHEN I COME TO A STOP THE ENGINE STALLS BUT NOT EVERYTIME. WHEN ECCELERATING THE ENGINE SOUNDS AND FEELS FLAT, DOESNT WANT TO GO INTO PASSING GEAR BUT SEEMS TO RUN FOR THE MOST PART FAIR. AUTOZONE RUNS THE CODES AND IT COMES UP MULTIPLE MISSES AND MASS AIR FLOW SENSOR IS BAD. WE JUST REPLACED THE M.A.S AND THE FUEL PUMP AND THE TPS. WHAT ELSE MIGHT IT BE? I AM AT A LOSS.
AnswerHello,
I don't think you will care for my answer because you will not hear an absolute answer for an intermittent prolem, but I will give it to you anyway.
You are trying to repair an intermittant problem by throwing money at it. I understand the frustration you are going through in which you cannot depend on the car and this problem only shows up at times.
I have no idea as to why you replaced the fuel pump. An electric fuel pump is either bad or good and is not something that is going to cause stalling and rough running at times.
I can understand checking the codes and possibly replacing as mass air sensor, but you did not mention if the service engine soon light was on while you were having the running problem.
Except on rare occassions, I don't lije people to go to auto zone or like kind stores because it has been my experience they are only parts people that will sell the customer as many parts as they want and have no automotive repair experience.
You need to understand that if a code is set for a tps, o2 sensor, mass sensor, whatever, this does
not always mean the sensor is faulty. It could be anywhere in the circuit including the bcm. In fact, multiple codes could be the computer or something going on in the wiring harness.
Intermittent drivability problems are the worst even for a seasoned technician.
If possible before changing anything else, you need to see if you can find some common factors. This may not be possible, but if you don't try, all that will happen is that you will keep throwing money away replacing good parts and still have the same problem.
Examples: does the problem present itself after the engine runs for 10 minutes? Does it start when hitting a bump in the road? After it starts raing? Outside temps hot? Cold?
You need to see if you can find out if there is some way to isolate. If not, you may have to wait til the problem happens more frequently until it can be diagnosed.
Trying to fix it without knowing the exact problem is going to cost you a lot of money.
Good luck
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