Ok. Here is the low down
97 GXE with 63k miles. Auto tranny and all stock. Oil changed every 3k miles. Ever since i bought the car with 52k miles, it has been problem free, except ridiculous rattles of course.
Recently, it has developed a strange noise under acceleration. Note: this only happens when the car is moving, so if i stop it and open the throttle it sounds normal. When accelerating from about 2000-4000 rpm I hear a strange noise, that sounds like something fluttering under the hood. It's not noticeable before 1800-2000 rpm and after 4000. But I think I can't hear it after 4k is because the engine is louder than the noise. Someone suggested a possible exhaust leak. In that case, wouldn't the car still make the noise when park and open throttle is applied?
I'm looking for any possible suggestions to this issue. Note: there has been no MiL or anything of that sort. About 4 months ago I cleaned my throttle body with carb cleaner and a toothbrush. I didn't notice if the noise surfaced after that, but thought i mention it to help you guys diagnose the problem. I will attempt to record the sound with a microphone and hopefully someone can identify what is is. Thanks a lot
Anton

 

Have your exhaust manifold checked. I have a friend that had a noise under acceleration that wasnt evident at a stop when the throttle was opened up. It was his exhaust manifold. Also check for any loose plastic splash guards under there. I had a loose one that would flap in the wind - but then again, it should happen all the time, not just when over 2000 rpm. Hope this helped.

K

 

Could be pinging. I have a 97 GXE w/60k. I have had this problem for 6 months now. I have always use 93 octane fuel. I too get the noise when about 3-4k rpm. People have suggested it may be because I use Mobile 1 and since its thinner, the timing chaing is noiser. This problem may have started when I used an injector cleaner before a trip. Maybe Daniel B Martn can tell us if an injector cleaner can cause these pinging problems.

I don't think it's a knock sensor, I would have expected a engine light. I'm at a lost here. Keep us posted on what you find out.

Thanks,

 

n/m

 

Pinging, also called engine knock, has a sound often described as an unpleasant irregular metallic rattle, similar to shaking a coffee can full of marbles. Pinging is pronounced when the engine is under load, such as climbing a hill or rapid acceleration.

SweetSound2001 describes "something fluttering under the hood." This doesn't fit the usual description of pinging.

Causes of pinging include:
- fuel AKI too low
- ignition timing too far advanced
- lean mixture
- carbon deposits in combustion chambers
- EGR valve stuck closed
- EGR passages obstructed with soot
- EGR vacuum signal hose(s) split, broken, or disconnected
- engine running too hot

There are other vehicle sounds which are similar to pinging. The most common example is an exhaust system heat shield which has become loose and rattles or buzzes, especially at certain engine RPMs.

Your Maxima has a Knock Sensor which detects pinging and signals the Engine Control Module (the computer). The ECM responds by retarding the ignition timing to eliminate the pinging. For this reason... if your Knock Sensor is working... you have never heard your Maxima engine pinging.