My car has a mines ecu and is running about 14psi boost, it has a decat exhaust and two dump valves,

 

When i accelerate up to full boost sometimes there is a rattling noise from the engine...

 

What could this be, is it the turbos?

 

Cheers

Sounds like detonation to me. Does it happen around 3500rpm upwards ?

This could be detontation.

 

Does it sounds like static ? Or a bag of nails shaking.

 

If it sounds like static it's det. (lower the boost in hotter weather, use 99 ron or V-max super pertol).

Bag of nails ?. More than likely either your turbo's on thier way out or it could be the heat shields come loose. Any sign of smoke when you accelerate ?

sounds like det to me too, try turning the boost down to see if it maakes any difference

Will do, what is detonation and how can i cure it? The car still performs well it just has the rattling noise, there is usually a tiny amount of black smoke when i accelerate

TURN YOUR BOOST DOWN till the problems solved or you will knacker the engine.....

 

Heres my recent thread on the issue.

 

http://www.300zx.co.uk/forums/showthread.php?t=111538

 

 

Work your way through that thread, have you replaced anything on the car recently??

 

Could be timing, boost leak, fuel starvation, spark plugs, ect

If it is det it's probably just due to the hot weather we have had recently.

 

Detonation is the result of the fuel / air heating up to such an extent that it tries to ignite before the spark is introduced.

 

This will cause down pressure on the piston before it's ready. This will cause increade pressure on the pistons and the weak spot of the lander between the piston rings.

 

As I've mentioned above, you need to make sure you are using higher octane petrol to reduce the risk of ignition before time, and also turn the boost down 1 psi to 13psi.

 

Other options are to upgrade your rad / intercoolers.