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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Nissan
Satisfied Customers: 560
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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Developed a knock yesterday morning. At startup everything

Customer Question

Developed a knock yesterday morning. At startup everything is quiet and smooth. from 1000 to 2300rpm quiet underload, from 2300 to 3500rpm knocking(not a heat sheild rattle) unless I drop off the throttle then quiet. On cruise control at highway speed about 2000rpm a very light knock that is harmonic in nature
JA: While using the cruise control can you accelerate or decelerate? Have you checked the fuses?
Customer: (louder then quieter) if I turn on air conditioning it gets better but doesn't go away.
JA: What is the model of your '00 Nissan?
Customer: 2008 nissan frontier 4.0L 4x4 crewcab lwb SE
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I haven't tried anything yet. I gingerly got it home yesterday and am developing a plan of attack now.
JA: Anything else you think the mechanic should know?
Customer: The knock is between 2000 - 3500rpm under load and not under zero throttle.
Submitted: 3 months ago.
Category: Nissan
Expert:  Jay replied 3 months ago.

Hello my name is ***** ***** thank you for your question

Since this is a noise, it is very hard to determine what it could be since I can not hear it. I have seen octane ping, exhaust heat shields and all sorts of things make noise under acceleration.

If you are stopped and you hold the brake while in gear and give the truck a little gas so it revs and tries to move when on the brake can you duplicate the noise?

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