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Discussion Starter #1
I need help identifying where this noise comes from, which starts exactly at 7,500RPM.

I don't have an exhaust system (straight exhaust pipe).
The noise appears even accelerating in neutral.

 

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I need help identifying where this noise comes from, which starts exactly at 7,500RPM.
Visit AutoGuysLand to review what rpm should my car be at in case you need.
I don't have an exhaust system (straight exhaust pipe).
The noise appears even accelerating in neutral.

Im not sure if i can help you or not but try. Noises can be caused by worn or sticking hydraulic lifters due to low oil pressure . Another cause may be broken lock on tensioner. Just thinking about these things and take a look at them. Good luck.
 

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Discussion Starter #4
New update. I ran it in dyno, and i realized that the VVL doesn't engage (we disconnected the VVL valve and it has the same power as with the valve connected, 210HP), so I deduce that the engine has been working all the time with the profile of Low speed cams across the entire RPM range, so that may be causing the noise.

Now I will uncover the valve cover and take a look.
 

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If you still hear the intake sound change at 6200 (or wherever your lift point is set) then your VVTLI is working and you have the high cam. If the VVL is not functioning you just don't get the fine-tuning of constantly variable intake cam.

Does the engine clatter for a second or two on cold start? If so that is a sign the VVL cam gear is at or nearing the end of it's lifespan.
 

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Discussion Starter #6
If you still hear the intake sound change at 6200 (or wherever your lift point is set) then your VVTLI is working and you have the high cam. If the VVL is not functioning you just don't get the fine-tuning of constantly variable intake cam.

Does the engine clatter for a second or two on cold start? If so that is a sign the VVL cam gear is at or nearing the end of it's lifespan.
Yes, sometimes it has a very short scratchy sound when cold start. Can you show me a reference photo of the VVL Cam gear? Thanks

PD: The VVL stopped working right after changing valve seals. I also replaced the VVL Solenoid with another (used). Today I will test the operation of the solenoid.
 

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That's the sound you don't want to hear. It's fairly common in Toyota and Honda VVT systems. Since the cam gear uses oil pressure to vary it's position, once they start to wear out the low initial pressure allows the cam to go through the full advance>retard motion repeatedly until pressure is high enough for it to work properly. Not good for the cam gear, or the timing chain/tensioner system, probably kinda rough on the cam too.
The VVT gear is the bigger one bottom left of the picture:
1870134355-2.jpg


Here is a short demonstration of a bad Honda VTC gear:

Now just imagine that happening 20-30 times per second while your engine is making that scratchy sound on cold start.
 
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