I have a 2003 Maxima SE with the 3.5L with an automatic transmission. It seems that when I get to about 35-40mph and just under 2000 rpm I begin to hear a knocking or pinging type noise only when I am accelerating. The check engine light has not come on at least yet. I run the premium gas. Any ideas what this could possibly be? Thanks for any input.

 

- DIY run self diag or go to autozone for free tst just dont do what they say). Maximas as most current engines have a knock sensor to detect pinging. Its failsafe: ign is retarded if KS dies, but still ignition may be not working. Self diag should indicate that. Checking ign timing with timing light isnt a big deal, do that.
- check/buy a diag tool, be always on top (smbdy recommended http://www.scangauge.com/ )
- check for any loose part(s), belts. Possibly engine/exhaust or whatever touches chassis? ...if so, driving with 1&2 there should be same noise at different rpm.
- plugs out, what do they look like? Compare www.ngk.com -site plug problems troubleshoot chart... (see: sparkplug411 /Plug problems)
- Compression tst is relatively cheap and straightforward to be done at 'any' service.
- As this noise is very poor to diag-no-see/hear over internet, go find a place where Maxima knowledge is high not every stealership has that), ask for diagnosis ... MOST important: go take a second opinion before anything i$ done.