Nissan Repair: 1992 Nissan Maxima SE, nissan maxima se, new computer system

Question
QUESTION: My 92 Nissan Maxima SE ( 5 speed ) has been in a reputable shop for 9 weeks and they still can't figure out whats wrong with my car so I'm asking you, please help!!!  What's happening is sometimes it acts like it's not getting gas or air ?? for just a couple of seconds causing it to jerk, it will go fine for a few minutes or do it consistently, for days at time it doesn't happen at all. They have replaced many parts and still this happens, now they are going to try replacing all the coils and plugs. This is getting very expensive and need my car, I can't continue to rent and borrow others vehicles. Is there any thing you know of that would cause this ? Thanks for any information you can provide, Nola

ANSWER: Hi Nola -

Have they checked the fuel pump? I am surprised only now they are thinking about the plugs and wires. That should have been the first to check as it is the least expensive and the most likely.

Anyway, to get a better picture of what is happening, would it be possible to tell me exactly what was replaced, checked and done to the car? That way I have a picture of what is going on, kind of hard to diagnose when sight unseen.

Hope this helps - let me know -
aloha
calvin

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

QUESTION: Aloha Calvin,

First thing they did was put in a new MAS then checked the other sensors, next ran leads to the fuel pump, computer and one other place that I don't remember they put in a new computer system even though that lead didn't show any problem. Today I was told they checked the plugs and are the wrong type for this model. I don't understand how it ran perfect for the last 3 years with these same plugs but that's what I was told so they are replacing them to see if that's causing the issue. If the plugs don't fix the problem he said they were going to replace all the coils. The last time I drove it with it doing the jerking ( gas, air or power loss ???? ) I had a little under 1/4 of a tank of gas, it was jerking really bad so I stopped and filled it up, when I cranked it back up it didn't jerk at all, ran like a new car. I had the same thing happen years ago and it was a short in a wire to the MAS. I really don't know what to think at this point. Thanks for getting back to me so quickly,
         
         Sincerely, Nola

ANSWER: Hi Nola -

Usually when the coils are bad, it triggers the check engine light (intermittent misfire code), so I would not replace the coils yet.

In my opinion, if the check engine light was never on, then most of the items that were replaced did not have to be replaced.

Anyway, I would still check the fuel pump, since you have evidence that it jerks badly when you are at 1/4 tank.

Let me know -
aloha
calvin

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

QUESTION: Aloha Calvin,
They got the plugs but said they received the wrong kind and can only locate 2 of the right kind in all of the south east. They said the plugs that are already in and have worked fine for years are the wrong kind. ??? I'm very confused about the plugs, how did this car run so good if it had the wrong plugs in it ?  Why can't they find the right plugs for this car ?  As for the fuel pump, I was told they ran a lead to the fuel pump and it was working correctly. 10 weeks now and they still haven't resolved the problem, it's very frustrating. I wish the check ingine light would have been on so maybe they could figure out what the exact issue is. I've never had such a problem getting a car repaired. I'm ready to take it else where but I've been taking my cars there for many years and have always trusted they would get the job done quickly and a reasonable rate, though it has been very expensive a few times. I don't know what to do at this point. Thanks for your knowledgeable answers and if you can tell me about the plugs I would greatly appreciate any enlighten.         Thank you, Nola

Answer
Hi Nola -

I checked with my connections here and there is no special plugs for this vehicle. If you get me the part number and brand of the plugs you were using, I can tell you if it was the correct one. However, you are correct, if the engine was running fine, then I don't know why you were told that.

A lead to the fuel pump (in my opinion) does not cut it. Were they just checking for power? Fuel pumps have 2 tests, volume and pressure. Also, the reason I say fuel pump is that a defective fuel pump normally will not activate the check engine light.

Perhaps you should get a second opinion since they seem to be stumped, but in my opinion, someone needs to check that fuel pump.

Hope this helps -
aloha
calvin