since i bought my Z i have noticed engine knocking while idling. it occurs every 10-15 seconds but varies greatly. it is always after the car is warm and has been driven. the noise is not present while driving. the car is not throwing a cel. is this normal operation, or should i be worried? can anyone report similar results? only mod is nismo intake, but this problem has been present before and after installation.

i am also hearing a rattling noise right after the clutch is engaged but it seems to stabilize after a couple of seconds, the whole trans assembly was just replaced not a week ago. rpm's are not affected.

i have done some research and i am planning on buying and installing an oil catch can because i figure this could be a product of octane reduction due to oil blow-by.

2004 with 46k
always 93 octane
mobil 1 5w-30

any thoughts, ideas, or soutions?

 

pinging won't generally be a "timed" event. It will knock or not knock. It doesn't go on at off at idle unless you have a dirty air filter or it may be something else. Are you certain it is detonation that you are hearing?

The clutch noise is common..It's a "marbles in the vacuum" sounding tranny.

 

i am almost certain it is detonation, like 99%. it is not rhythmic and it is always there. like i said it varies greatly, sometimes it will be a serious of knocks, while other times it will be a few spread out and then stop for a little while.

 

If you are detonating at idle you have serious, serious issues... I highly doubt thats happening.

Are you on the stock ecu?

 

yes, only mod is the nismo intake, and that is irrelevant. they are audible knocking sounds. i obviously cannot say that they are surely detonation knocks, but i don't see any other alternative...?

i would assume that the computer would correct itself and retard timing but the knocks do not go away even after a few minutes, they do decrease in frequency though.

 

http://www.technosquareinc.com/350reset.htm

 

Could be mechanical knock (ie, rod knock), as opposed to detonation. And you are correct, if the ECU was getting knock signals from the knock sensor, it would be pulling timing like mad.

I just highly doubt that you would be knocking repeatedly at idle, the ECU doing nothing about it (unless it was retarding max timing), and yet having no audible knock at higher rpm/engine loads. Your timing and fuel maps would have to be crazy, and given that you are on the stock ECU that is not a possibility.

You may be experiencing bottom end knock or valvetrain noise that are getting covered up as rpm's rise and so does engine noise, or you may be crazy in the head

 

i have this same issue actually, exact same symptoms...i tried taking my G35 to the dealer twice for it and they say they have not been able to recreate the issue. they even claim they let it idle for periods of time with the computer hooked up and still saw nothing.

It still happens and apparently the original owner complained about it as it was on file with infiniti.

I describe it as more of a small backfire note but not as loud, so its like a little knock. its something i can feel in the pedals and shift **** if my hand is on it. I too also had a nismo air filter and I recently put my stock intake back on, its not as loud, but I still hear it and feel it just as frequently.

Im going to a different dealer for it this monday, warranty is over soon so I hope to get some answers.

 

hm i think i heard it on mine too.. iam not sure...but it drives fine and pulls strong as hell... im not too worried anyways.. iam going to build the engine so.. i suggest u do the same.. and then boooost! =)

 

It may just be a misfire. Change the plugs. Cylinder pressures are too low for true knock at idle. I'm not saying you're not hearing a knocking sound - only saying that it's not due to detonation or timing. Much more likely to be a mechanical issue. Have you mis-shifted and over-rev'd the engine? Rod, valve, piston slap, damaged bore - lots of possibilities...

 

of even your vavles need to be re-adjusted

 

have you considered hydraulic cam chain tensioner?it'll make a lot of noise and be intermittent.

 

ah yes - there was also that cam sprocket TSB as I recall... that was just supposed to be a start up sound though.

 

it may be misbehaving when the oil thins out,like an internal bypass.something like this would clean up as rpm raises (so does pressure and tension on the chain).just a thought....i cant hear it in person so it's anyones guess.to the op if you can't recognize the sound,mechanic shop till someone does.

 

the solution to every problem huh?

Yeah I know its not rod-knock, my old accord ran with a mild rod-knock for years so im quite familar with it. I've always describe it as a "knocking" misfire or back fire event.

I was curious about plugs too, i haven't bother checking them to see how they look, maybe I'll do that today, but i doubt I'll have time. im still schedule to get it looked at monday, i just hope its present while at the dealer and i'll mention the cam-sprocket tsb.

 

Interesting my car started ping going up the hill to my house three weeks ago I can hear it all thim low RPMS no more than 2k it pings like crazy took it to the dealer twice they did a idle relearn and then said "we have no Idea, go back to stock and see if the fixes it or just drive it the way it is." My mods are Nismo CAI and Cat back.. Change Nissan parts for Nissan yea that'll do it. The best was "just drive it.." LOL. PS 51k miles and now out of warrenty( Time).. Going to another deaker and paying the $100 for Diaq on Thursday.

 

I went to the infiniti dealer yesterday to get this looked at again and was for the most part pleased. I was able to talk and work with the Mechanic personally. After waiting by the car a little bit while it idled we were able to get the noise to come about.

He describe it as a mis-fire (which was my initial impression), but it wasn't causing the engine to readjust timing or the air-fuel mixture while he had the consult hooked up to it. He even pulled out the stethoscope, but couldnt really pinpoin the source.

Since my problem doesnt seem to be effecting my driving or cause any bad reads, he said just drive it unless it gets worse and more repetitive. In the meantime he said he would keep an ear out for it on other cars and let me know what he finds. if he does or not we will see, but all and all I was very pleased this time. he also noted it in the cars log so that whenever I take it in to any dealer it will be checked.

 

Atleast you gpy some answers I got "your ALFA is 130 and should be 95, But we have no clue whats wrong so drive it.. "

 

Thats what happens with a high load at low RPMs

 

Yes it does going up hill is when I hear it the most. I can hear it all the time under 2k RPMS once it goes over that it goes away. I press the pedal maybe half way and just starts pinging. If I hold the throttle were it is it will ping till I get the top of the hill then there is less load on the car and the RPM's will start to go over 2k.. Man its so loud