QuestionMany thanks for the suggestions. I should have mentioned that I installed a new fuel filter about 6 mo. ago. As soon as I have a chance I'll do a fuel pressure test (I have the tools) and run some injector cleaner and premium fuel through the engine. I've had a look at the fuel pressure regulator so far -- application of vacuum seems to produce the appropriate response. I did notice that the vacuum line (to control solenoid) seemed a little loose, so I'll replace it. In the event that the regulator turns out to be OK and the problem persists after cleaner etc., what would be next on your list? Might the cylinder head temperature sensor, for example, be a suspect?One item that puzzles me is an apparent variation in high-tension current in some spark plug wires. Some wires seem to have intermittently stronger and weaker pulses -- i.e. using a neon bulb-type tester. As mentioned, I replaced rotor, dist cap, and h-t leads not so long ago. I'm wondering if perhaps the coil or coil power transformer could be acting up and causing this. I realize that this problem -- if it is a problem -- may be unrelated to the stalling, hesitation problem, but thought I'd raise it in case you had any experience of such things. Thanks.
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Followup To
Question -
I discovered that the 02 sensor on my 1988 Maxima was the cause of hesitation, stumbling, and almost stalling problems a few months ago, so I replaced it. The sensor had been replaced after an emissions test failure about six months before that. The engine seems to be developing the same symptoms again, which suggests that something in the system is fouling the sensor. I'd appreciate any thoughts you may have about identifying what may be the source this problem. I have replaced the ignition wires, distributor cap, plugs, etc. not too long ago. The car has about 125,000 kms on it and is otherwise in excellent condition. I generally try to do whatever work may be required myself, but if anything that is inordinately time-consuming or that requires equipment I don't have to hand comes up, take it to an indie mechanic. I'm aware that there are a range of ignition/fuel system/emissions components that may be at fault, but would appreciate the benefit of experience in pinpointing likely suspects. Thanks.
Answer -
Paul,
If the oxygen sensor was replaced and that corrected the problem a while back and you suspect that it was damaged by something up stream I would be looking at a fuel problem. This is especially true since you replaced all the ignition components. I would be looking at a new fuel filter and some fuel system cleaner along with a couple of good tanks of premium. Also, check the fuel pressure regulator to make sure it functions properly. You will need a fuel pressure gauge to do this.
AnswerPaul,
Have you checked the distributor for oil on the optics. The distributor uses an optical shutter wheel much like a mouse for a computer. There is a seal in the bottom of the distributor that keeps oil out and after many years it fails and the oil tracks up the shaft and gets on the optics and makes things intermittent. if you take the cap, rotor and rotor post off you can get to the cover that hides the optics. Take out these two screws and the shutter wheel is underneath. Any oil is bad so if there is oil on the shutter or optics replace the distributor with a rebuilt one.
