# '02 Altima random misfire code, makes a noise almost sounds like knocking



## G33kyG1rl (Nov 4, 2014)

Recently bought an '02 Altima, about 171k miles. Got a great deal. In real nice shape, but make this sort of "knocking" sound under the hood when you're first taking off. Drives great otherwise. When I test drove it at the dealership the first time it drove so bad I was gonna walk, but they changed the plugs (which they said were in really bad shape) and offered a second test drive, it was much better. Still getting a check engine code for random misfire though. Thinking maybe one of the coil packs is going. How do you test them? Also when we got it, the engine oil was too high. Husband changed the oil and it's now at the right level. Hoping that didn't cause the issue. Any thoughts?


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## SPEEDO (Jun 9, 2003)

which engine? misfire code, which cylinder? you could move the coil from one cylinder to another and see if the code follows to that cylinder..


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## G33kyG1rl (Nov 4, 2014)

The engine is 2.5. It's a "random multiple misfire" code, not linked to any coil pack in particular.


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## SPEEDO (Jun 9, 2003)

in that case check into the cam/crank sensor kit (oem pt# B3731-6N27K)


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## G33kyG1rl (Nov 4, 2014)

Weirdest thing. Tested it again a while back and tied it to cylinder 1. Moved coil pack in cylinder 1 to cylinder 2. The misfire codes ceased. Car was behaving for a while. We hadn't replaced any parts, then again we weren't driving it long distances, maybe a few miles at a time. Then, today, it shut down again. No engine codes. Rented a code reader from the auto parts store. It read:

HTD Catalyst N/A

No idea what that means. Assuming it has something to do with the catalytic converter? Would that cause it to just stop, and not start up even after sitting 12 hours?


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## G33kyG1rl (Nov 4, 2014)

So we've replaced the catalytic converter, or rather the entire pipe that the catalyst is on. It still kept stopping. We also replaced cam sensor and crank sensor with the ones with the metal on the end after that. It's still doing the same thing. I really have no idea what to replace now. At a total loss after just dropping $200 in probably unnecessary parts. The car is not driveable at all, and 2 people rely on it to get to work. Any help would be much appreciated.


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## rogoman (Dec 16, 2004)

You were probably getting a code P0300 (Multiple cylinders misfire). Here are several things that could cause this code:

- Improper spark plug
- Insufficient cylinder compression
- Incorrect fuel pressure
- Dirty injectors
- Intake system vacuum leak
- Heated oxygen sensor 1 (front top)


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## G33kyG1rl (Nov 4, 2014)

rogoman said:


> You were probably getting a code P0300 (Multiple cylinders misfire). Here are several things that could cause this code:
> 
> - Improper spark plug
> - Insufficient cylinder compression
> ...


That's the funny thing, the computer isn't popping any codes at all anymore. Why would it be shutting down like that without popping codes?


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## rogoman (Dec 16, 2004)

Check the engine grounds for tightness and any oxidation. You might consider SPEEDO's recommendation for the sensor kit.


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