ruff sound, after car warms up

[Tr8er]

so ruff knocking poping ticking . all ecu codes 55 . fresh oil ever 3k , starts fine with the ide at about 1.2k slowly drops to 1k. then it sounds ruff once its fully warmed up from a cold start it drops to around 700rpm if I give it just a touch of gas to get it to around 1krpm the sound pretty much goes away. any ideas as to what could be the problem,. I could also video this and post it if need be

[BusyBadger]

Is this for the 300Z listed in your profile? This is the 350Z Tech area. I can move it if you need me to.

[djwarner]

Back in the days before OBD, we'd be looking for a vacuum leak leaning out the idle mixture.

[Tr8er]

yes please move . and from what I can tell watching youtube vids of a kinda the same thing. the nearest sounding one. ended up being his timming belt auto tenser not working , but like I said the second it hits 1k-1.1k rpm the sound drops to like 10% I can hear it because I know what it sounds like but im thinking its more of an oil lifter problem maybe? I don't really know what that sounds like when they start sticking one way or the other. but if its timming related could I just move the CAS around a bit? "to check it" , also il check for vac leaks over the weekend I have had to take the intake hoses off to redo power steering belt. but it was making this sound before that, thanks in advance il record the sounds via my phone once I leave for work tonight if its not raining

[t.mcginley.jr]

A video would be great if you could take one with your phone or something and put it on youtube.

[300ZXttZMAN]

Hmm so I see your car has 120k miles. Have you done the 120k timing belt service?

[Tr8er]

no, but the belt and water pump was replaced, by the shop that sold it to me about 2 years ago at 109k. car is at 125k give or take right now

oh I think I failed to say this all started after a bad oil change, "free oil change card" and they put 5 qts in ran it for a few quick trips around town before I checked it (high oil pressure / low power) drained it and refilled with 5w40 and that's about the time it started making the noise but the ide wasn't dropping , checked codes had a 34,and I want to say 16 ( the water temp sensor) both fixed / relocated and now the ide has a mind of its own

[Tr8er]

http://www.youtube.com/watch?v=8EmpcfN1wEw

so I did this one ,5mins or so after a cold start before I had a temp reading rpms dropped to 800ish , turned defrost on rpms jumped to 1.1k sound volume dropped but can still be heard on this video, turn defrost off rpms drop hard and slowly come back up to around 800

[Tr8er]

okay so messed with my idle air control a bit it was screwed down as far as it would go back it out a few turns , that seemed to fix the sudden drop after being warmed up , Im also running oil treatment for a few more days before I drain it and few fill with fresh oil. if that doesn't kill the sound I guess the only other thing I can think of is its timming related. I have my idle reading around 1k no noticeable sounds, but that might have been more of a bandaid fix than the real problem

[Tr8er]

so ran lifter clearing , no change. so I broke down and ordered the timing kit maybe it will solve all my problems "120k kit" we will find out in a week or so after I have time and clear weather or pay some lucky soul to do the work

[Ziggy1621]

Def a top end noise. Too solid sounding for a lifter. Lifter is more of a tick. That's a clack. I'm going to refer back to Mark's suggestion of the timing belt. Pull the radiator and get down to the timing belt and count the teeth. I would not suggest running it too much and def not revving. The FSM shows you how many teeth between each gear. Don't forget to set it at TDC to make it easier. Then test the clearance on the tensioner. I would hope they would have done at least the 60k if they changed the water pump, but I just helped pull a motor that a certain company put in, and nothing surprised me with some people's quality of work.

The company Im referring to has the name of an illness you get from time to time that causes your temperature to rise in case anyone was curious.

[Tr8er]

okay so all timing parts replaced, ending up redoing the cooling system hoses radiator ect.. new harmonic balance drive belts , so the works as far as stuff I could think of , anyways Car sounds perfect , not quite to sure what the root of the problem was but the timing was off a hair no teeth skipped or anything, so maybe just a mixture of 21 yearold parts rattling around lol, so if you car sounds like mine, check the timming

[Ziggy1621]

Nice job! Just an FYI these motors are internally balanced, so it's not a harmonic balancer, just a crank pulley