Nissan Repair: Catalytic Converter, 97 Altima, diagnostic checks, pep boys

Question
QUESTION: Hello,
My girlfriend's 97 Altima has been having a problem with sputtering and dying lately. The problem initially began with us not being able to start it a few months ago. We had it towed to an autoshop and the mechanic replaced the spark plugs and wires and it ran well until just recently.

REcently it started sputtering at about 40 mph or 1000-1,500 rpms, then a few days ago it started dying completely after being started. The car always restarts, and trying to get it home from the airport I managed to get it on the interstate where it ran just fine once above the 40 mph mark. Getting near the house I got off the interstate and it ran perfectly well. The problem is that sometimes it runs fine and other times it will die 5-10 times, either at idle or at about the 40 mph mark. Took it into Pep boys and 2 diagnostic checks turned up nothing. We took it to another place and they said it was the catalytic converter, then said that it may be fuel pump and filter. My concern here is that they want to replace the pump and filter first and I'm concerned that they're creating more work and overcharging (they quoted a new catalytic converter at $400 and I've found them online for around the $140 range)

So, i guess my question is, does this sound like a catalytic converter issue or a fuel pump issue? And would $400 be a proper charge for a catalytic converter from a mechanic?

Thanks for your time.

ANSWER: Jason,

Pulling the fuel pump is a pain since the gas tank has to be dropped.  Also, the issue with catching the car on fire.  I would leave that to someone that has the tools if you do not.

If the converter is defective it is usually caused by the fuel injectors leaking or being defective.

The sputtering is probably the distributor having oil leaking up on the shaft causing the optics to get coated.  Replacement of the distributor would be in order.

---------- FOLLOW-UP ----------

QUESTION: Von Sudderth,

First, thanks for the input.  I never really had any intentions of trying to replace the fuel pump myself, was just ignorant on the cost of labor more than anything else.

As a follow up, the mechanic at Pep Boys suggested to my girlfriend that she have the fuel filter replaced and see if that fixes anything.  A couple days later the car died again and wouldn't restart. We had it towed to a different Pep Boys and they ran a diagnostic check which came back with misfire and knock sensor. We replaced the distributor and the knock sensor, and things were good for a day or two and now we just had it die again a couple times.

So I know I'm kind of slow here, but I assume the replacement of the distributor alone is just fixing the symptom, but am I correct in understanding you would suggest replacing the fuel pump, injectors, and the converter? Money being as tight as it is right now i'd like the cheapest fix (though I guess there's not a lot of people who wouldn't) so are all these issues connected or is there a most likely suspect?

anyway, again, thanks for the response and I'll be anxiously awaiting the next one...

Jason

Answer
Jason,

Most of the time, after you have all other codes repaired and cleared the next item would be the mass airflow sensor.  Problem is that it does not usually throw a code.  I would have a shop check the unit with a digital volt ohm meter to verify if it is functioning normally.  Since the car runs when it runs it would not be the converter.  Usually, the converter will plug and the car will only run for a short time, several minutes, until it gets warm and blocks.  So, yours should be fine.