Constant Knock And Low Boost Problem

[W0rp3D]

took the car to calder a few weeks ago, for an unknown reason (at the time) the boost started going up to 22psi when it was tuned at 18psi, had a look and checked vac lines and possible leaks but there was no problem, it still ran fine and there was stuff all knock (35 max a few times), tried changing the settings on the gizzmo boost controller but didnt change any thing so i just ran it how it was, as i was leaving i had another look over things and discovered that the vac line from the cooler pipe to the wastegate solenoid was off so effectively it was running unlimited boost which only hit 22psi!!

the next day with everything back together i took it for a spin but on the old settings the turbo only hit 13-14psi, had to up the settings by about 20-30% to get it to 18psi again, also there was a bit of an odd noise coming from the turbo, sort of like the squeal my standard turbo made when it died but it was only about 20% as loud as the standard was.

One of the things i thought it may have been was the shitty intake from the airbox that i made up when i put the 3540 on, so last weekend i put the hks pod back on, the old settings still give the same 13-14psi but now on 18psi the knock regularly hits 40-60 and on a setting where the boost hits 19-20 the knock hits 140-150, i cant tell if the extra noise from the turbo is still there or not because the intake is so loud it drowns it out.

I do realise that the extra knock is probably because of the free flowing hks pod leaning it out but what could be causing the settings to have to be raised to get to the same boost that it use to have?

I know from when i had the tune that there is a restriction, most likely the xforce cat, going to have atleast one of the mufflers replaced as it is atleast 7yrs old, question is what else could it be, temp stays around mid 70's dosnt lose water or oil and there is no oil in the catch can.

The only other thing i think it might be or might be contributing is the gasket between the top and bottom half of the manifold, it sounds like its leaking but i cant see anything and the engine idles like normal, tried spraying some brake cleaner on it to see if the idle changes but it dosnt, it dissipates pretty quickly but i dont know if its evaporating or being sucked through the gasket.

And then theres the last 2 options, i have hurt the engine or turbo, the two that i least want to be true!

Any idea's or suggestions are welcome.

[paulr33]

id say you cleared up a restriction somewhere and its not using cells which havent been tuned as well as the others

this will drive higher knock as the timing may be too high in those cells, or the AFR too lean

the intake temp could also be too high from compressor out of efficiency as well