# Need help troubleshooting a Pathfinder Engine Problems



## Matthewts (Oct 20, 2009)

98 Pathfinder started bucking and choking and running rough. I started with the basics and changed out the fuel filter and put a bottle of gas treatment in the tank. It ran great for about 10 days (fluke ?). Then it started again (different gas) but now it seems to run find when the engine is cold but once the engine gets warmer it starts bucking and running rough again. Took it to Autozone to get the codes read and came back with P0325 Knock Sensor 1; P0340 Camshaft Position Sensor; and P0731 Auto Trans 1st gear malfunction. So does one or both of these sensors need to be replaced or are they just symptoms of another failed component ?


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## OkcOffRoader (Feb 25, 2005)

my GUESS is the cam sensor is bad , and it set off other codes too....check and clean all the connections on those sensors before buying anything....then test drive....


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## Matthewts (Oct 20, 2009)

Performed some additional "general" troubleshooting today and determined the Mass Air Flow Sensor is good (started suv unplugged sensor, truck died). As well messed with the EGR Valve and it seems to operate properly when quickly revved up to 3k rpms (per service manual instructions). However, when the engine is revved up to 3k rpms and you let off of the gas and it begins to drop rpms quickly it stumbles around 1800 rpms for almost a full second. . . any thoughts around that ?


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## Matthewts (Oct 20, 2009)

Anyone else thinking cam sensor ???? Or something else ???? Anyone know the approx cost of the sensor(s) and how many there are ? is it an easy diy project or one better left for a trained mechanic ?


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## robbryl (Sep 29, 2009)

*Maybe this will help...*

I have an 87 Pathy and it was doing the same thing as yours, it would run like a skinned chicken...until it warmed up, then it would start to buck and jump and eventually it would lose all power, I did it all diy style, changed the fuel pump, the fuel filter, the coil pack the throttle position sensor, and still the same problem, me and a team of mechanics located the problem in the Air Flow Meter, since my Pathy has no Mass Air Sensor, this would have to be the logical choice for me, I would try the Mass Air Sensor If I were you, granted you pulled the connector and it had a reaction, those sensors also react at certain RPMs Under Load which you can't check while driving down the road, and the cam position sensor would definitely be something to consider, especially if codes are coming up, diy style, again clean the sensors first and put them back in, if that does not work, do the cheaper one first, and see if that helps, hopefully this made a little bit of sense to you, Good Luck!!!


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## NALtech (Oct 30, 2009)

Definatly the cam sensor. It's possible that it set the trans malfunction but it definatly set the knock sensor code. I see it alot, if you have a running problem 99% of the time the knock sensor will show up.....FYI Get the sensor(s) from the dealer. I know what your thinking but it will last longer then an aftermarket one. I have seen it many times expecially on the 2.5's. They will throw in parts store crank/cam sensor and maybe 1-3 weeks later it goes out again.


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## Matthewts (Oct 20, 2009)

Well, this is an 89 with the 3.3 6cyl and I called the dealership today and the parts guy said that they aren't listing a cam position sensor for this engine but rather the distributor cap. Is he correct ? Is the cam position sensor in the distributor cap for this engine ? or did he mean distributor ? Or is he incorrect all together ?


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## NALtech (Oct 30, 2009)

I'm not sure on a 89, your first post said 98....


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## Matthewts (Oct 20, 2009)

*98* 1998 is the correct year, sorry


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## NALtech (Oct 30, 2009)

Then yes the cam position sensor is built into the distributor.


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## Matthewts (Oct 20, 2009)

So is it reasonable to say that replacing the distributor (which contains the cam position sensor) this will fix the problem ? Is it fairly common that it would run fine with the engine cold and then start having problems when warmed up when a cam position sensor needs to be replaced ? Just working on a budget here and trying to spend my $$$ wisely.


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## NALtech (Oct 30, 2009)

With the ECM not having a cam position it's gonna run like crap if it runs at all. Let me look tommorow at work with ASSIST and see what Nissan reccomends.


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## Matthewts (Oct 20, 2009)

It runs and drives perfect for about 5-10 minutes (until the engine warms up). Then it coughs and sputters and bucks and @[email protected]!


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## IanH (Feb 11, 2003)

sounds more like a temp sensor, check the air and coolant temp sensors.


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## IanH (Feb 11, 2003)

But i don't see how that fits your codes ??
So is it possible you have poor connections somewhere, dist or bad knock sensor.
O2 sensor might mess with the mixture enough, but shouldnt it go into limp mode ?


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## IanH (Feb 11, 2003)

howabout you get the codes checked cold when running well and when hot running rough ???
If there is a change will give you somewhere to focus on.


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## boogyman (Jan 24, 2005)

My version of the shop manual is corrupt, but there should be a sensor under the distributor cap. If you replace the cap, it should run a whole lot better. I had a similar problem with an old Jeep. It would stall and start up for no reason. Figure out I had multiple problems. The cam sensor and the crank sensor were bad and causing me all kinds of headaches. While you are changing the cap, do the rotor also. It's only a couple bucks and you are in there anyway. If your truck won't start at all, a bad crank sensor will not let you get spark, so it will look like a bad coil. Just a little info for down the road. good luck.


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## Matthewts (Oct 20, 2009)

New cap and rotor installed. No change !!!! Still starts right up and runs fine when cold and then once the engine warms up to normal operating temp. . the bucking and choking begins. . What Next ? and ideas ?


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## boogyman (Jan 24, 2005)

Ok this may sound out there, but one other thing could be the fuel pump itself. It may be working, but overheating. I know it's an expensive part to just replace and I wouldn't want to do it unless I was sure. How full has your tank been when having the problem? Since it's cooled by the fuel in the tank. Maybe someone else can come up with another idea or confirm mine? Sorry I can't be more help. I would think the fuel pump would throw a code if it was going bad though.


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## Matthewts (Oct 20, 2009)

The gas tank has always had at least a 1/3 of a tank of gas at all times. . .still trying to get this one up and running


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## OkcOffRoader (Feb 25, 2005)

check ALL of your vacuum lines, then do it again...almost sounds like a tempurature actived vacuum switch is opening, then an open hose is sucking air...another thing may be O2 sensor, they dont operate until it heats up..im just throwing ideas out there, might be something to look at.....


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## Matthewts (Oct 20, 2009)

Replaced the coolant temp sensor and no change. . .Finally gave up and decided to take it to a small independent shop. New Distributor is the diagnosis. . .


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