# Random missfire and P0300 code



## garyh_rosies (May 7, 2004)

Hey guys and Ladies:
I bought my daughter a 98 pathfinder with 107,000 miles on it and we love it.
Just the other day the service engine soon light came on and I had it checked and did the normal replacements of fuel filter, cap, rotor, wires, plugs and timing belts. Also added some fuel injector cleaner.

I reset the computer(taking the positive cable off the battery) and did a test drive. 
Light came back on.
I put my ear down at the tail pipe and I can hear a slight random miss only at idle. The engine runs smooth to redline and gets good milage.

What do I check next.

Thanks Gary 
Tulsa, OK


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## DanTheMan (Jan 12, 2003)

*Get a tune up*



garyh_rosies said:


> Hey guys and Ladies:
> I bought my daughter a 98 pathfinder with 107,000 miles on it and we love it.
> Just the other day the service engine soon light came on and I had it checked and did the normal replacements of fuel filter, cap, rotor, wires, plugs and timing belts. Also added some fuel injector cleaner.
> 
> ...



Maybe a tune up (with timing adjustment) would help, or just timing check.
Maybe better gas.
Use some carb cleaner/TB cleaner and open her up on the highway to blow the damn carbon out....
How about a FI cleaning or new injectors?
Lots of mileage......get a code scanner at autozone/checker and you can clear codes prior to emissions, just be sure to reset the "readiness flags" and make sure the CEL is off when you go.
I think it's jut an older engine that doesn't like our watered down 2.30/gal gas.


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## 1986.5 SEV6 (Jan 9, 2004)

I have an 87 and on my V6 I have an Anti-Backfire (AB) Valve (really). If you have the same engine maybe yours is malfunctioning.

Mine was located directly infront of and slightly underneath the air filter (for a picture do a parts search on the web). I just pulled it off and plugged the line and it has not effected my engine performance. You could try the same. If it fixes that problem you've found th culprit, if not, just put it back on (just one bolt and the hoses).

Good luck


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