Turbo boost problem from a newbie

[wowow]

Hi all, My car had a cracked turbine shaft when i bought it a few months ago, and took me a while to find a stock unit. But now I discover other issues with a working turbo :

On 1st gear, car revs up to 3.5k with ease and turbine starts spinning. As I continue to floor the gas pedal ( well, maybe only 80%), the rev stays around 4-4.5 and the car starts to loose power. Even if the turbo doesn't generate any extra power, the car should have behaved like a NA engine and keep revving up, but it didn't.

On 2nd 3/4/5/6, the car behaves "more" normal and does feel like a 300bhp car. Turbine spins at 3.5 k and power comes on at 4k, and keep increasing up to 6k, that is, if I continue to press on the gas. If I rev up to 4.5k and try to keep it at that rev ( as I go into a bend and try to keep the rev ) , the engine stutters. Blow off valve is working fine as it makes a very loud but nice wishing sound whenever I shift to the next gear ( left off the gas ).

Could the problem be an aged wastegate spring that opens to soon, hence no power on 1st? But 2/3/4/.. All works fine and the waste gate must be holding pressure. Or could it be a cut off from the ECU because rev cannot increase on 1st? The reason for a ECU cutoff because the waste gate not opening and pressure increase to a level too high ? That should be the case because the waste gate does open on 2/3/4/... Or could it be a default sensor that gives signal to the ECU causing the cut off? All your expert advise will be much appreciated.

If I do have to replace the spring, and doesn't mind having a bit more boost, what is the maximum "spring rate/ boost rate" I can get without having to upgrade other components?

[PhilT]

Probably not a lot of help, but why not take it to a specialist?

[Lloyd]

I suggest you post your problem on the S2Forum. You may get some more advice there.
Otherwise, as PhilT says take it to MRCTuning or Cockings Motor Repairs.

[wowow]

Problem is, I live in Hong Kong and specialists are limited.

[Shoppinit]

Sounds like a fuelling problem. Isn't there an AMDtechnik in hongkong?

[darkhorse1210]

Wowow

I have a spare OEM Pierburg Fuel Pump available if that turns out to be your problem. Let me know if you need it.

Tom

[SpeedView]

The reason for a ECU cutoff because the waste gate not opening and pressure increase to a level too high

THIS.


Sounds like you're overboosting there and running out of fuel. This is not good - it'll detonate and break/melt things.

Who fitted the replacement turbo? What was disturbed when it was replaced? How was the wastegate adjusted? Is the wastegate actuator hose connected properly and free of leaks? Do you have a boost gauge? What does the boost pressure look like at various rpms?

Usually the reason a turboed car stutters at 4.5k but is fine at 6k is that the turbo can't generate the same maximum boost at 6k as it can at 4.5k. I assume it drives fine at half throttle?