Hey guys,

When I put my foot down on the throttle (usually 1/2 way or full throttle), I can hear a pretty distinct rattling/chattering noise coming from my engine, which will stay there somewhere between 2-3,500 RPM and then dissipate. I have no idea what it is, it sounds like something where you shake a can of spray paint or something. It's really light, not too loud, but its there and its definitely not normal. It's easier to hear when I'm in a higher gear and I hit the throttle.

I recently had my short block replaced by Nissan in an attempt to fix my oil consumption on my 06 Base. It has 61,xxx miles on it and 1,250 miles on the new short block.

Any advice would be greatly appreciated, thanks!

 

Normal. Whether it's called pre-ignition, or pre-detonation or knocking or pinging or whatever is more of a contentious issue; however, that sound is normal at low rpm if you're hard on the gas.
Shouldn't really be putting your foot into it at low rpm like that, anyway. If you are in a hurry, get that b!tch in a lower gear and then twist its tail. You will get much better results.

 

Have you taken it back to the dealer to see what they have to say about it? I'm assuming it wasn't there with your previous engine. I seem to recall reading something about this problem though. Search a bit and see what you can come up with.

 

My 05 chatters/knocks at idle but runs great and gets 29mpg hwy... No loss in power but it just sounds weird idling when warmed up. using 93 octane as well...

 

Hahahahahahaha Dave, that was hilarious. Thanks for the laugh and the info. You're right, it seems to happen only in low RPM and accelerate, but goes away as the car goes faster into higher RPMS. If I have even the slightest bit of music playing of the window rolled down, you dont hear the sound. I know nothing is wrong with the actual engine, no lights are on or anything of the sort.


Thank you STL & Sidewayz,

How the hell do you get 29mpg? Most I was able to get was 27 in my 03 when I had it. Awesome!

Sidewayz, I'm on an oil consumption test right now and if they end up replacing the short block again, I'll see if that noise goes away or not. For now it's not so much a big deal. But no as far as I can recall the sound wasn't there before the short block was replaced.

One off-topic random question: is it me or do the RevUp motors seem much slower than the 03-05? Hmm... I was driving with my AC on yesterday and oh man the car felt like it didn't want to move at all. I guess less torque really makes that much of a difference!

 

I drive highway all the way to work. I have new oem plugs, new air filter, royal purple 5w30 oil change, royal purple transmission oil change, I use non ethanol 93 oct gas from a local station and I drive it easily in town. I am getting 29.8mpg right now and it's not uncommon for me to see the distance till empty gauge reading this....

 

^^^holy heck!!!!

i've own my z for more than 4 years now and never once have i ever saw my MLS that high. the most i would see is 360mls. and im happy if i get 23mpg on the hwy. youre lucky!!

 

I don't know what makes my Z so different but I will take a pic of my current MPG and DTE when I fill up tomorrow.

I thought all Z's were getting this sort of dte.... "shrug"

 

This is from this morning when I arrived at work.



And after $50 gas... didnt top it off or there would be a higher dte. (Saving for wheels so I am being quite Jewish)

 

I've had mileage in that range for reasonable, long distance, HIGHWAY driving to/from work. I found that the gauge/meter thing was less accurate than miles driven divided by fuel put in, but your fuel economy is not freakish.

 

OP, do you get this very light tapping/knocking sound only when the engine is cold (after a long drive it doesn't happen as much, if at all)? Also does this get worse with more throttle/load? If so, it sounds like the block was built with too much cylinder wall clearence, piston slap.

This normally get lighter as the engine heats up because the parts expand and take-up more of the gap that causes the slap.

 

I would never consider a knock or rattle to be "normal" as someone suggested. The new engine might have a little piston slap like Zazz93 suggested...but definitely seems like valve ping to me. Don't ignore it. I can have my DE in high gear and press it to the floor...no rattles, just a low roar slowly increasing in intensity

 

Sorry if I led anyone to believe that's normal for a stock engine. In NO WAY, SHAPE, OR FORM is piston slap ok on a stock engine, or for that matter is loud valves. Any way you look at it, it likely needs to go back to them. Hopefully it hasn't been too long.

 

That is some crazy @$$ MPG man!


Guys, how the hell do I know if its piston slap? The sound is really faint and you can hear it when my windows are rolled up all the way/no music playing, or if I'm driving next to a bunch of parked cars and I throttle. Sometimes its misleading because it also sounds like its coming from under the car, but when my windows are rolled up and whatnot you can distinctly hear it from the engine. Now I'm even more worried than I originally was, sigh......

 

No the sound is always there, and the sound does get a little louder if I throttle more, but not much. But it's always there

 

One more thing.... if it IS piston slap, will this be covered under my 1 year 12k warranty Nissan has given me???????

 

Definitely! If that is truly the case, it means they built the short block wrong.

 

Thank you Zazz, I was just looking at videos on youtube on piston slap noises and I can honestly say my car does not sound like that. I'll have to pop my hood and check for knocking noises, but last I did that I didn't hear anything out of the ordinary. I'll check near the front wheels too. When I start the car when its super cold, and the RPM's jump to 2.2k, at that point I hear a slight rattle for less than half a second and it goes away. When I rev my engine, I do not hear noises (at least that I know, I'll have to test everything out). But if this is piston slap then wowie Nissan is gonna be pissed lol. I'll have one of their mechanics get in the car with me next time I go for an oil consumption test to hear what I'm hearing.

 

One other thing that could be, bad throwout bearing. That actually occurs at all temp ranges. Does the sound originate from under the car in the tranny/clutch area? This sound is a rattle sound and like you say it is generally audiable until about 3500rpm. I've noticed whenever I disconnect the the pilot shaft without changing the bearing it tends to make noise after. If I remember correctly, I could engage the clutch and the sound would go away, also I remember the sound was most noticable on decel in that range 1500-3500.

 

I hate the fact that I can't go over 4k RPM's when I'm breaking in my engine still, UGH. But honestly I need to test what you are saying. I think I'll bring it to 4k in 2nd and 3rd, 1/2 throttle where its most noticeable to hear, and see if the sound goes away after 3,500RPM. The sound DOES sound like its coming from under the car WHEN MY WINDOWS ARE ROLLED DOWN and I'm driving past some parked cars. I can hear the sound bouncing off the cars and it indeed sounds like its coming from underneath the car in the tranny area. I can't be 100% certain but its definitely the front where the engine is. This car DID have its transmission changed because of 5th gear grind, tranny under warranty. However, on decel the sound is not audible at all. I'll give it a test. This is great info, thanks a million!