QuestionWht do you mean by "oil on the optics"? Thanks Again
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The text above is a follow-up to ...
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Hello, I have a Nissan Frontier 2001, 4 cyl automatic 130k miles. I get the obd code p0301,cylinder 1 misfire, every other time I drive the vehicle. I had the truck to the Nissan dealer and was told that I had a leak in the intake manifold gasket. I had that repaired and after a while I was still getting p0301. Before I brought the vehicle to Nissan I changed the plugs,wires,cap,rotor and fuel filter.After bringing the vehicle to the dealer several times and them not being able to solve the problem I was told that it is probably a ECM issue and that it is not worth spending the $500-$700 to change it. The truck runs fine,no hesitation or anything indicating a problem, just p0301 every other time I drive the truck. Maybe its just me but I just don't buy that. There has to be something. I went to a local garage mechanic that I use ocassionally and he worked on it and said my EGR was faulty and should be changed. Had that done and the fuel injectors checked and I still get p0301 every other time. Anything I might have missed? The truck runs fine with no signs of oil burning or anything indicating a failing engine. Thanks, Bill
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Bill,
If it is a cylinder 1 misfire I would be working on anything to do with cylinder 1. First, change the plug with another cylinder and see if the code follows it. Next, if that does not work do the same thing with the plug wire. Next, take the distributor cap, rotor, rotor post and cover off and check for oil on the optics. I would concentrate on cylinder 1 and see what is going on. Specific codes usually mean that something is going on with that cylinder. Also, do a compression check of the cylinder and a leakdown too. Anyway, this is what I would do if it were mine. Just work from the cheap to more expensive until you get it resolved. Email me back if you need more. And, I really do not think the computer is defective.
AnswerBill,
A Nissan distributor is much like your computer mouse. There is a shutter wheel that looks like a small CD disc with slots in it. It sits under the cover that is under the post that your rotor installs on. There is an LED and a optical receiver that are situated on each side of the disc. The distributor has a shaft seal that eventually wears out. Then, oil works its way up the shaft and gets on the optics messing up the signal to the computer to fire the plugs. Since you say number 1 is messing up this could be the cause. You see, number one has a specific value for the optics and that is what lets the computer know that number one is on top. Well, oil on the optics and then you get a error code for number one. So, that could be a cause. Take the cap, rotor, rotor post (there is a screw on top of the post) and then the cover and you will see the optics. Do not worry as there is only one way it goes back together since the parts are indexed. So, just take your time and keep track of the parts. If there is oil on the optics get a rebuilt distributor.
