Wild Knocking From Vq30 Intake Plenum

[cuttz]

Hey guys I'm after a replacement intake plenum.

Once the engine is warm and the butterfly's in the plenum runners open it make a some wild knocking or tapping sounds so I think the intake is stuffed.

Does anyone know where I can find a new one.

Thanks rossco

[cuttz]

Car is a 2001 v35 skyline fyi

[scotty nm35]

I have a spare VQ25 DD intake, not sure if they are the same, but I doubt the intake could make those kinds of noises. I suspect your cam advance mechanism has failed on one side or the other.

If you try unplugging one of the blue plugs on the front of the engine to see if the noise goes away, if it doesn't, try the other blue plug. (Note: you will need to clear the code afterwards)

[cuttz]

Thanks for the reply.

We had the mics on the intake and it's coming from the dead center of the intake.

but ill check with the plugs to see if it goes away but it only come one you apply power

[cuttz]

For all those that is interested the noise had nothing to do with the butterfly in the manifold.

It was the left bank variable cam timing spring.

One damn spring was 450 bucks.

and was a huge job to do. So we unplugged that bank. And running no vct.

[scotty nm35]

For all those that is interested the noise had nothing to do with the butterfly in the manifold.

It was the left bank variable cam timing spring.

One damn spring was 450 bucks.

and was a huge job to do. So we unplugged that bank. And running no vct.

I fix it in situ using S/H parts, takes a couple of hours. Pretty common issue with the 2.5 and 3L.

[Sianco]

Hi All,

Sounds like I have the same problem on my 2004 RX250 Stagea, Its got the VQ25DD and has 197000 on the clock.

Mechanic has looked at the car and unplugged the left hand sensor, fixed the noise but car has the engine light on now and is running sluggish.

Does anyone know of a sure fire way to check if it is spring or just the sensor playing havoc with the valve timing?

My mechanic here in NZ has said the parts alone for the spring job are over $500.

Would like to have it confirmed that is the problem before parting with that kind of cash.

Thanks.

Simon.

[scotty nm35]

It will be the cam actuator assembly hitting the end of it's travel, not necessarily the spring. Do you know what grade of oil your mechanic was using? I usually try a thicker oil before swapping parts, as the camshafts need the correct grade to work properly, they could also need a re-learn.

$500 for the parts sounds cheap if they are new, the job may be quoted much higher if you include labor, it's quite a job to replace, especially if he wants to drop the engine.

[Sianco]

Hi Scotty,

Thanks for the reply.

Have checked the last service sheet, oil used is 10w40 semi synthetic.

Is a relearn something my mech can do with his diagnostic comp or is it specialised?

$500 was just for parts, reckons entire replace with labour could be over $1100.

Worth a shot with the oil first.

Would this be the reason my screen on the Navi system has said PIT since getting the car in February???

[scotty nm35]

That oil grade should be fine, but for the cost of an oil change without filter a thicker oil could be worth a try. I doubt his aftermarket diagnostics could reprogram the cam actuation, you need a Consult 3 unit to do a lot of these higher level diagnostics.

Has it been banging long? If so the assembly could be damaged anyway.

The PIT symbol is just a service reminder, it doesn't know there is something wrong afaik.

[Sianco]

Scotty, you are a star.

It staggering the amount of info that you contribute to this site.

Thank you so much.

May be damaged as was knocking from about May till i got it serviced in July.

Roughly 5000k's

I'll try to find someone with a Consult 3 unit, after an oil change.

Will let you know if this has worked.

Thanks again.

Simon.

[scotty nm35]

No worries Simon.

I am able to change these assemblies through the front cam cover, where the blue plug is. It's not something I would suggest to someone who has never pulled a DD apart before, but I could help your mech with basic directions if he needs them. He will likely want to drop the front cover though, it would be the best way to do the job right.