1998 Infiniti Q45 Spark Plugs

  • 1 POST
  • 1998 INFINITI Q45

Engine Performance problem
1998 Infiniti Q45 V8 Two Wheel Drive Automatic 141000 miles

I get a knock or ping when I drive and the accelerator is stationary, not accelerating or deccelerating, I dont think the engine has had a tune up for some time, and has COS system, I am not getting a "service engine soon" light. Will a colder or hotter spark plug help and or bosch platinum +2 or +4 spark plugs be advisible. I have replaced the air cleaner, put Mobil 1 oil and Mobil 1 filter recently, the engine has plenty of power during acceleration and is responsive. Please advise.

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Sunday, October 19th, 2008 AT 11:10 AM

1 Reply

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I would stick with the OEM plugs. I have them listed below. Once you pull one of the other ones you can see what was in there. My thought is your plug schedule is every 60,000 miles. If you have never changed them as you can see, they should have been changed twice by now.

Spark plug ID

Standard PFR5G-11

Hot type PFR4G-11

Cold type PFR6G-11

I would also consider changing the plug wires. OEM again. Next the fuel filter. It is possible that the ignition timing is off which is causing the knock, but since the plugs are long over due I would change them first and then drive it a few days and see how it does. You have knock sensors on this car. I have attached the location and how to test them.
Hope this helps.

Find a car repair manual for your car - Repair Questions



Knock sensor

Disconnect knock sensor harness connector.
Check resistance between terminal (2) and ground. Approximately 500 - 620 K Ohms at 25 C (77 F)
It is necessary to use an ohmmeter which can measure more than 10 M Ohms.
CAUTION: Do not use any knock sensors that have been dropped or physically damaged. Use a new one.

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Sunday, October 19th, 2008 AT 10:43 PM

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