Turbo boost problem from a newbie
Posted: Sun Nov 27, 2011 3:30 pm
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?
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?