1996 Nissan Maxima knock sensor

Tiny
MSGPVIRGO70
  • MEMBER
  • 1996 NISSAN MAXIMA
  • 6 CYL
  • 2WD
  • MANUAL
  • 218,789 MILES
My check engin light came on so I went and had it put on a diagnastic mech. The code that came said I needed a knock sensor. What does this do and why do I need it?
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Wednesday, September 23rd, 2009 AT 9:19 PM

4 Replies

Tiny
BLUELIGHTNIN6
  • EXPERT
The knock sensor responds to spark knock caused by Pre-detonation of the Air/Fuel mixture. As the flame front moves out from the spark plug ignition point, pressure waves in the chamber crash into the piston or cylinder walls resulting in a sound known as a knock or ping. This is caused by using a fuel with a low octane rating, overheating, or over advanced timing. Sometimes it can be caused by hot carbon deposits on the piston or cylinder head that raise compression. A knock sensor is comprised of Piezoelectric materials; Crystals that when impacted, generate a voltage (same idea as a BBQ ignitor). This voltage is monitored by the computer, and when an irregularity is detected, the computer corrects timing in VVT (variable valve timing) engines, or triggers a DTC (Diagnostic Trouble Code) in older vehicles.
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Wednesday, September 23rd, 2009 AT 9:24 PM
Tiny
MSGPVIRGO70
  • MEMBER
When I step on the gas there is a loud knocking in my engine. This started about the same time as the knock sensor light came on. Also the car has trouble picking up speed. Do you think this my be related to the knock sensor?
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Wednesday, September 23rd, 2009 AT 9:36 PM
Tiny
BLUELIGHTNIN6
  • EXPERT
Yes, most definitely.
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Wednesday, September 23rd, 2009 AT 9:37 PM
Tiny
MSGPVIRGO70
  • MEMBER
Thank you soo much. Im having the knock sensor replaced on saturday. Ill let you know how the car runs afterwords.
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Wednesday, September 23rd, 2009 AT 9:43 PM

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