# Running rough, need help!



## Cptnplanet (Sep 5, 2015)

I recently just installed a new distributor cap, plugs, wires, and fuel filter while installing a new water pump. I've put 10,000 miles on since then. Everything was running smooth until recently. Two weeks ago I started it up to leave work and it was idling rough. I gave it some gas and it smoothed out. I didn't think anything of it until I started it this morning and it was running rough. Unlike last time the idle did not smooth out and now runs rough no matter what rpm or how warm the engine is. I checked the fuel filter, plugs and wires and everything is fine. Not sure what else I should look for. it has 145,000 miles. I know its due for its second timing belt.. not sure if that could be it? I'm going to put a timing light on it and see if it is off. Any suggestions are much appreciated. Thank you
Preston


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## smj999smj (Jan 1, 2006)

Well, it's possible that the belt jumped a tooth. It's sounds like you have a misfire. Try taking spark plug pliers and removing disconnecting one spark plug wire at a time and reinstalling it (with the engine running) to see if you can isolate a misfiring cylinder (the engine RPM will not drop if you disconnect a spark plug wire on a misfiring cylinder). Fuel injector failure and/or poor connections in the fuel injector harness connector weren't uncommon on the ol' J30 Maximas with the VG30E engine. Make sure that cylinder is getting spark, has proper compression and use a noid light to check for power to the injector and to make sure the ECM is "firing" or "pulsing the ground circuit" that fuel injector. Also, check for vacuum leaks.


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## Cptnplanet (Sep 5, 2015)

So I pulled each spark plug wire one at a time like you said. All but one made the car run different (#3 cylinder) Like I said it has new plugs and wires so I'm guessing a fuel injector?


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## jdg (Aug 27, 2009)

Cptnplanet said:


> So I pulled each spark plug wire one at a time like you said. All but one made the car run different (#3 cylinder) Like I said it has new plugs and wires so I'm guessing a fuel injector?


So, a new plug or plug wire has zero chance of failing?
Maybe you swap #2 and #3 plugs and wires and see if you get the same results.


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## Cptnplanet (Sep 5, 2015)

Already did that but thanks. Going to buy a noid light and see what I can figure out from there.


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## smj999smj (Jan 1, 2006)

I wouldn't be surprised if the injector is bad. As I said earlier, it was a fairly common problem on them years ago. These days, you don't see as many of them on the road as there used to be. They were a pretty good car!


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