# 98 Nissan Altima GXE shakes violently in run



## gnvs (Sep 8, 2009)

Hi,
I have a 1998 Nissan Altima GXE with 158K miles on it. There is one perennial problem in it for which I need help with. The car shakes violently when running (mostly at 60+ mph) and this happens at random. There is an service engine light and I showed it to multiple people and they say it is the probelm with air knock sensor. Was wondering if anyone has seen such symptom before and the remedy to it, please?

Also, i used a fuel injection cleaner couple of months ago and the mileage on the car dropped from ~30mpg to ~21mpg. any help!!

Thanks
gnvs


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## pulsar86 (Aug 13, 2009)

The milage drop may be to do with some dirt shifting when you used the injector cleaner, that is holding an injector open. I think the shaking is more likely to be wheel and tyre related than to do with the engine.


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## gnvs (Sep 8, 2009)

So, should I use another cleaning cycle to remove the dirt or how to bring the mileage back to normalcy?


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## pulsar86 (Aug 13, 2009)

Try cleaning again first but they may have to be removed to check if they are operating properly on a test rig. Have you had the sensor that is causing the check light replaced, a faulty o2 sensor might also cause the fuel problem by causing ecu to alter mixture. Come to think of it the vibration at speed might be the engine misfiring badly because of incorrect fuel air mix. Does the vibration go away if you go into neutral gear and coast without throttle, while it is happening, if it does it is probably engine related. Is the sensor a o2 sensor or a knock sensor? A faulty o2 sensor will cause a mixture change, a faulty knock sensor may be causing the timing to be too far retarded and cause the heavy fuel use. Best of luck.


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