Off throttle knock

[godspd701]

My brother got an R32 skyline GTR not too long ago and we are trying to figure out what is wrong with it. It is mostly stock but it seems to have a Mines ECU.

The problem is that it makes a knocking noice. I have heard a valve before on other vehicles and this doesn't sound like a valve. It is a lower pitch klunk type of noise. It mostly does it once the car is warmed up and when we drove it yesterday it only made the noise when we would get off of the throttle. It sounds lioke it is coming from the rear of the engine. Compression is 130psi in all cylinder except for the rear most cylinder which is 10-20psi less. It still seems to pull strong but my brother doesn't realy know what it was like before the knock happened.

Thanks.

[Blitz]

I may be wrong but 130 psi sounds a little low, and the rear cylinder showing 10-20% less, combined with your knock is a concern.

I dare say your engine is in need of a strip down and rebuild