i just recently bought a 04 G35 coupe with 62k miles on it. Well i notice that when i start the car to let it warm up its idles really low, almost at the line before off. And sometimes there is a faint knocking sound? When i cut the car off it almost sounds like my exhaust rattling but im not sure. Any thoughts or ideas on this?

 

If the SEL (service engine light) is off you might want to try the throttle body re-learn. It is in the following link.

https://g35driver.com/forums/intake-...-cleaning.html

If the SEL is on I would pull the codes and go from there.
I would also get the motor running good before trying to diagnose any sounds.

 

Yea no lights on my dash are on, i just noticed it idles really low and there's some kind of rattling sound. but when the car is idled up to around 800rpm or 1000rpm the sound stops, which makes me think the sound is from the motor spinning so slow??? And then when i cut the car off every time it gives this rattling sound again but my windows have to be down to hear it. But with me i assume the worse and think its a knock in the bottom end which would be terrible.

 

The rattle at shutdown might be exhaust, broken heat shield maybe.

 

I have that low idle issue as well. I'm thinking about taking it to Nissan to see if they can raise the idle maybe 500 rpm.... No clue if they will or if it'll be reasonable $wise.

Pops , blips, knock, whatever you wanna call it... is probably just the normal strange noises the G makes at idle. At least that's what the dealer will tell you. Has always seemed strange to me. If it's a legit knock then I would suggest having a qualified mechanic or Nissan take a look at it because that could be a serious problem for ya.

By rattling noise when you cut it I assume you have a 6MT. If that is the case it's most definitely the flywheel/pressure plate. Same thing with mine. Not harmful as far as I know, but definitely annoying. I just compress the clutch when turning the car off every time now. Gets rid of the rattle.

 

I'd try re-setting the ECU (battery disconnect) and then the TB relearn mentioned above if not cleared. If the car is idling as low as you say it could need the MAF sensor cleaned. Before resetting the ECU you should find out if any codes are being generated as not all will trigger a dash light - most autopart stores will do this for free.

Those clunking noises you're hearing could be a combination of valve-train rattle and low speek knock - neither are good for it so don't let this go on too long.

 

thanks guys im going to try the ecu reset as well as the TB relearn tonight to try and get my idle up. The only thing i can figure is i have cold air intake on it and maybe that's why the idle got screwed up. I also depressed the clutch just now and shut the car down, no rattle, seems to only do it when the car is idling at the low rpm. Im going to also check the exhaust and heat shields today. Thank god for a prior passion in mustang that lead me to buy a car lift lol

 

Shane H85 I just took my g35 to the shop with the same question they said when you turn the car off and you hear that rattle it's normal. It has something to when the clutch disengage as you are turning the car off so don't worry about it. Sorry I can't explain it like they told me