Problems with Boosting

[Ants200sx]

I wonder if you could possibly give me some assistance. I am currently running a stage 1a chip
The problem I have had is the car doesn't seen to boost any where near to 1.2 bar. I can only currently get about 0.8 or round that figure.
I have change the turbo do to a crack waste gate.
turbo fins were broken,
The actuator has been change to a forge style.
Pressure tested all joins seem ok.
Check forge re circ valve and have now changed it to pigeon mod.
Profec boost controller removed and a manual bleed vale put in place.
Profec solenoid changed.
Boost piping to car and actuator checked

After all if the above has now been changed and I am still having issues.
can anyone please give me advice,,

Could this be the dreaded DET???

[wyatt1]

isit mis-firing around 4k - 5k revs? the past 2 times ive unplugged my MAF due to working on the car (changed the turbo once, fitted a fmic) it stutters, hesitates and misfires like mad and wont boost, however a quick good clean of the MAF and a little spray in the plug and she runs like an absolute dream. completely transforms the car, just my 2 bob could be worth a try before changing plugs/coilpacks ect.

[Ants200sx]

No mis firing at all runs like a normal car.
After I changed the turbo it's went like it should for about 2 mins and now it's back to low boosting.
Is this the cause of carbon desposits killing the turbo again due to DET???

[Mustard200]

Did you put the turbo and manifold back together properly? As in using the locking tabs?

[wyatt1]

did you replace gaskets ect?

[silviagtr33]

Didn't realise det caused carbon build up,not just running very rich?

[redsx94!]

Have much pre tension is on the actuator?

[Chriscooke]

Doesn't sound like det to me but then I genuinely have no idea what's wrong with it

[Ants200sx]

Did you put the turbo and manifold back together properly? As in using the locking tabs?

yep belive so all went back together OK

[Ants200sx]

Have much pre tension is on the actuator?

actuator is at a bar, borrowed off a mate

[Ants200sx]

Didn't realise det caused carbon build up,not just running very rich?

only found out myself recently, its on jez's website , Pre-ignition can be caused by hot spots in the combustion chamber - this can be the spark plug tip, glowing carbon deposits or other hot spot

[silviagtr33]

Ill have to look into that,my spark plugs and lambda sensor is covered in carbon,car was running rich tho,

[dalespencer]

Didn't realise det caused carbon build up,not just running very rich?

det can be caused by carbon deposits on top of the piston that retain heat and cause pre-ignition,
i would be checking maf wiring and lamba, you may of pulled the wires on the maf when installing the new turbo,

[rising son]

could it not be a problem with the chip..?

edit... probs not actually

[Joe1989]

Do you have an exhaust leak before the turbo?

[Ants200sx]

Ill check again.

[Ants200sx]

Doesn't sound like turbo gaskets etc.
anyone got any ideas.

[Ants200sx]

Anyone else with advice.

[M.D.]

Right so getting back to basics.

You have replaced the turbo due to wastegate cracks and damaged blades.
You say you have 100% checked for boost leaks. And I take it there is no exhaust blowing anywhere.

With all that given and the fact you say its running nicely but just not boosting properly it leaves only a few possible options. Firstly the actuator. It may be a bar spring in there but if its not got enough preload the flapper will open early and will "blow open" causing low boost.
So my first port of call would be to tighten the actuator arm so there is more weight on the spring.

With this done if there is no difference check where the boost gauge is taken from. Do not take it from the same vac source as the fuel pressure reg. ideally find its own pipe on the plenum.
Make sure there are no kinks in the pipe etc.
if no change check to make sure the gauge is working properly by borrowing someone else's.

Det would be fairly obvious if its happening as you will hear it. Sounds like two screwdrivers tapping together under load.

Finally and this is a bit of an extreme one. Take the oil feed off the turbo and get someone to crank the engine quickly. Make sure there is a decent amount of oil coming out. I've seen several now with blocked oil feeds so the turbo dies fairly quickly and struggles to boost due to friction from the failing dry bearings. Generally results in lots of smoke and death of the turbo so I doubt its this with yours but just throwing out there the possibilities.