Hi, I own a 2001 Nissan Maxima SE 20th Aniversary Edition, 5 speed manual. It only has 6900 miles on the odometer and I've changed the oil twice, once at 3944 and once at 6862.

About a week ago it started making a funny noise when accelerating in second or third gear at around 3000 rpm. It only happens when the engine is relatively cold.

The acceleration sounds fine, but on top of that is a noise that sounds like a light grinding, or like something is loose. The best way I can describe it is to say that it sounds like my car is getting over a chest cold. You know when you breathe and you hear the congestion moving? It's like that.

I'm going to take it into the dealer for work but I just want to have an idea of what I'm talking about. Any ideas on what's causing this?

Thanks,

Brian

 

words like "at XXXX rpm" and "only when cold" and not gear specific makes me think you have a heat shield loose on the exhaust system. They can make some odd noises.

 

My guess is that its that backpressure control flap on the exhaust that makes the annoying rattling sound at moderate acceleration. I hear it on mine from time to time but it doesn't get very cold here in Houston so you might be hearing the same thing only exacerbated by colder temperatures.

 

It's happened to me about 4 times in the past year. Accelerating from a stop at about 3000 rpm and it sounds like a light grinding/clanking/coughing sound. But it disappears in a few seconds and I don't hear it again; only happens when I first start driving. I'm planning on bringing this up in my next service, but if you find out anything, I'd definitely be interested.

5thGen
BC, Canada

 

Well, my service appt is for this Friday at 9. The service manager seemed incredulous when I described the problem. We'll see how it goes.

 

does it sound electronic? i only ask b/c my buddy has the same car .. but his car makes a very high pitched electronic sound on start up & shut down

 

No, I'd say it definately sounds mechanical.

 

does it sound electronic? i only ask b/c my buddy has the same car .. but his car makes a very high pitched electronic sound on start up & shut down

 

yeah i've got it, for good i think. i haven't noticed if it's excerbated by cold temps tho so i'll have to pay better attention. i thought it was lower grade gas that caused it cuz when i use good premium, it seems to diminish or dissappear. don't know

 

Interesting...I thought it might be a bad batch of gas. I think I may have put in 89 octane instead of 93 a few times without thinking.

 

The sound is not electronic; definitely sounds mechanical. As for gas, I only use 92 or 94 from Chevron. My next service isn't for a month or so, but I'm pretty sure they won't do anything since it's not reproducible. Since this wasn't mentioned in Maxima.Org before, I thought it might have been just me. Made me want to trade up to a 2002 'cause I thought my engine may be a bad apple. Glad there's a couple of you with the same symptoms.

5thGen
BC, Canada

 

I looked on autoweb.com and found this in the troubleshooting section:

Symptom: There is a rattling noise from the engine when you accelerate

Description of problem: Your car seems to run fine at all times. You notice nothing unusual except when you press on the gas pedal to accelerate or to go up a hill. Then the engine rattles like something is loose inside of it. Normally, this problem begins slowly and gets worse.

Probable Causes:

1. Your ignition timing needs adjusting.
2. The engine is overheating.
3. You have a loose vacuum hose on the engine.
4. You bought low-octane fuel even though your owner's manual says to only use high-octane fuel.
5. There is an excessive amount of carbon built up in your engine.
6. You have a problem with the electronic engine control system.

 

well, it's diminished somewhat for me. altho i still can hear it very faintly still. bad gas must have left some carbon deposits or sumthin.

 

I agree that is could be exhaust related, or it could also be related to a loose engine mount. At certain RPM a loose part will resonate creating that deep growl

 

The service manager said it sounded like a loose heat shield when I described the problem in person. They haven't called in with the final verdict yet.

 

when ya find out what it is lemme know cuz mine does it too, really sounds like its comming from the exhaust or at least somewhere in the back of the car

 

Nissan service didn't find anything wrong with my Maxima. To be honest, I'm not surprised. The service manager said they took it out twice and couldn't duplicate the noise, so it must have been bad gas.

I haven't heard the noise since I put in a batch of Chevron 93 Octane (with techron!).

 

i use only exxon or mobile and i use at least 89 or 93 octane and i have the same problem so i doubt its bad gas

 

I had been using 89 for the last few times without thinking. I re-read the manual and found that the 20th Anniv. requires 91 octane. So 89 would be considered bad gas.