1995 Nissan Maxima-P0301 and PO325

[NutriaforBreakfast]

Received these codes-engine misfire and knock sensor activated
suspecting coil pack problem or spark plug
Engine is missing at low speeds (miss may be covered up by engine noise at high speeds)
Any suggestions

[NutriaforBreakfast]

I replaced the #1 coil pack (by firewall on furthest passsenge side) and its running well.

Before replacing I had noticed drivability had gone down. I was hearing the engine
"lug down" some when going around 40 mph in traffic. The coil was originally going
out as the engine warmed up. You couldn't tell it was missing on the highway (high speeds) but on
the street at low speeds it was definitely missing.

I got the old coil and tried to ohm it out with the multimeter and it seemed like it didn't meet
specs per Chiltons. I should have gotten low resistance with one test and high resistance with another test-I got low resistance on both tests.

The coil didn't appear to be burned or physically different from the new
one so you cant tell a coil by it cover. The spark plug looked fine-typical grey ash color with
no apparant anomolies. I used silicon dielectric on the spark plug boot and antisieze on the
plug thread and cleaned the inside of the electrical connector with Radio Shack electronic cleaner.
Good to go! Lucky day!:rotflmao

[4ofclubs]

Have you replaced the spark plug? Also when i used to work at a parts store we would pull coils off the shelf and they would not technically meet the guidelines but they would still work, just as long as there isn't a drastic difference in what your ohmmeter says and the book it should be alright. Usually misfires do involve the spark issue but you could also be looking at an injector going out.

[NutriaforBreakfast]

Thanks. I ohmed out all the coils one time and got lots of variances. Have trouble
trusting the readings seriously but still try-like you said looking for BIG differences.
At the beginning of this problem I noticed I had filled up
at an out of town gas station and thought I got bad gas. After the second time of getting the
codes above I realized there was more to it than that.

I put the same plug back in since it looked fine-they are all less than a year old. I actually have a coil tester which checks the spark but haven't used it yet.

Will keep the injector issue in mind. I have replaced only one injector on the car with 200K miles so
it wouldnt suprise me to find a problem there. Actually I would love to do some maintenance
on the injectors and using someone who could clean them but I am just paranoid about
somebody else throwing them around like junk iron. Any suggestions here?

[4ofclubs]

well you could always try lucas or seafoam fuel treatment, or whatever brand you want those are the most popular. I had my injectors "cleaned" one time at wal mart they hooked up a machine to the injectors and its supposed to clean them, they didn't even have to take them out. Ive heard a lot of bad things about taking vehicles there though so i don't know if you would really want to do that but its an idea.