ALTIMA 99: ENGINE IDLES UNEVENLY AND VIBRATES.

  • Tiny
  • fuulhouse
  • 1999 Nissan Altima
  • 133,000 miles

My engine revolution is uneven, fluctuates between 900-1000rpm when starting from a cold temperature. When its temperature is higher, maybe after driving around for sometimes, it starts and stalls. Also, when on idle, it vibrates. OBD-2 scanner returned MAP sensor and Throttle position sensor problem. I ve replaced the throttle position sensor but it still does that. I did not replace the MAP because I dont its location and becos I read that most times, the MAP malfunctions because the throttle is bad.
I will appreciate any help on the MAP location and any other help to solve this. Thanks

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Wednesday, August 8th, 2012 AT 3:46 PM

6 Replies

  • Tiny
  • saturntech9
  • Expert
  • 29,299 posts

Please post the exact code numbers not code descriptions. That will make it a lot easier to help you.

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Wednesday, August 8th, 2012 AT 3:49 PM
  • Tiny
  • fuulhouse
  • Member

The codes from OBD-2 scanner are p0120 - Throttle position sensor, p0105 - MAP circuit malfunction, p0443 - Evaporative Emission control system purge control valve circuit. I ve taken the car to my mechanic who said the MAP sensor is ok. But it still does that. I need to add that the car surges forward when changing from Gear 1 to 2. Thanks

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Thursday, August 9th, 2012 AT 1:48 PM
  • Tiny
  • saturntech9
  • Expert
  • 29,299 posts

So does your scan tool read live data?

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Friday, August 10th, 2012 AT 11:10 PM
  • Tiny
  • fuulhouse
  • Member

I am not sure. But I ll check it. What should I look for?

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Wednesday, August 15th, 2012 AT 1:36 PM
  • Tiny
  • saturntech9
  • Expert
  • 29,299 posts

See what the tps sensor reads while at idle?

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Wednesday, August 15th, 2012 AT 4:32 PM
  • Tiny
  • fuulhouse
  • Member

While at Idle, the tps read 0%, while I accelarated with the gear position in park, the tps still read 0%. Intake MAP showed 1kPA. Thanks

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Wednesday, August 22nd, 2012 AT 12:27 PM

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