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Hello guys,
My car is now dynotuned. I got it done about a month ago and it runs great. It made 300rwhp/300rwtq so that's great, but I have one question. It seems like ever since I got it tuned, the valves rattle more on startup and they're decently loud for a good 20-30 seconds before they go quiet. What could be causing this? I'm assuming it isn't knock because it goes away after a short while. The tuner is very reputable so I doubt that's it either.
Thanks ,
Justin
 

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How many miles are on the motor? Is it the valves or could it be the cam phasers? An intial guess is that either its not getting enough fuel on startup or youre not getting oil pressure until that time has elapsed. What weight oil do you use?
 

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It was probably doing it before and you never noticed. The cam chain tensioners will bleed down over time ande on startup the cam chains will rattle until they pump back up. This rattle can occur when using different oils too. You should hear a 3v or Yote start up after sitting all winter. They make a hell of a racket for a couple of minutes until everything pumps up.

My 2015 rattles a little if it sits over night since I put Mobil 1 in it.
 

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That doesnt sound healthy for a new car. Ive always ran motorcraft 5w30 in my 07 gt and it doesnt make any noises after sitting.
 

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How many miles are on the motor? Is it the valves or could it be the cam phasers? An intial guess is that either its not getting enough fuel on startup or youre not getting oil pressure until that time has elapsed. What weight oil do you use?
It'll either be the worn cam phasers or timing chain guides rattling 'cause they're not getting enough oil pressure after initial start up.
Use a mechanic's stethoscope to localize the sound and work from there.
 

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Havent seen you in a while Bullitt. It seems like a lot of people are popping in every once in a while.
I'm still lurking around, logging in every day, but the forum's been pretty quiet lately so not many posts. :)

One thing I do know is that the engine shouldn't rattle after a first start no matter how long it's been left idle. I forgot to mention earlier about verifying that the oil pressure's normal with a mechanical gauge. If it's very low for a few seconds after a cold start, this could be a sign of impending oil pump failure. I think this is rather unlikely but it's worth ruling out for peace of mind.
 

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My car has 60+ psi of oil pressure on a cold start up. There should be no oil related issues. Usually when something makes noise on start up and then goes away is a worn part issue. It's loose until it heats up type of thing. I have one or more idler pulleys that chirp on start up and then go away after a minute or two. Worn bearings. Have you pulled the cam covers?
 

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Yea it has been quiet on here recently but I like this forum the best. I see a lot of us on s197 but skwerl and a lot of others dont like this forum and go out of their way to talk **** about us. Boss saw it, I thought for sure skwerl was going to start a forum war from what him and I said lol.
 

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Since installing the headers and cams I hear a lot of tap-rattle-clatter that was not as bad at startup before. It did not go away after reinstalling the stock cams and then putting in the Hot Rods. I used Mobil 1 and other full synthetics since first oil change at 900 miles and ever since. I installed a new fuel filter and better fuel pump but that did not change the noise. As a matter of fact I have a rougher idle since the fuel pump install and I wonder if the injectors have been getting worse over time and changing the fuel pump just gave it a spotlight. A bug that I have been chasing. This car is over 10 years old now even under 50k miles the beatings I put it through at the track almost every other week leads to its demise.

Get the oil pressure checked with a gauge and not the instrument panel during cold start up. If the pressure remains the same through warm up until the sound quiets then like Boss said, it might be a worn part that is adjusted by oil pressure but does not benefit the pressure until the working parts get warm enough to limit the oil from leaving the pressure side. Worn part will get worse over time and the duration of the noise will sometimes get longer or tax the oil pressure to the point where it can be seen if tracking it. You will need to see a pressure cycle of a start up of a engine that has no noise and compare it to yours if you see a pause or a lower pressure with yours and see equal pressure trend after a warm up I would say oil pressure issue and maybe a worn part but if there is no trend differences then I would look at the tune and or injectors.

You did not list your mods so it is just a guess based on what modding I have done and the noises I hear from my own engine.
 
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