Quick help please
23 March 2004, 05:09 PM
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Quick help please
Don't want to bore you with all the details but I blew my engine by putting 2.5 bar in 
(not a Scoob) The new engine is in and the car will be started on Friday. By what we can gather the vacumn pipe to the wastegate was disconnected and unfortunately the ECU does not have a fuel cut hence big det and engine written off. Questions are :
In neutral when you rev the engine does the wastegate open to limit boost.
If not is there anyway I can test the wastegate is opening and closing OK.
Is there any device I can install in the pipework that will vent all boost above 1.5 bar (never reach this unless there is a problem)
Any help greatly appreciated.
Thanks
David
(not a Scoob) The new engine is in and the car will be started on Friday. By what we can gather the vacumn pipe to the wastegate was disconnected and unfortunately the ECU does not have a fuel cut hence big det and engine written off. Questions are :In neutral when you rev the engine does the wastegate open to limit boost.
If not is there anyway I can test the wastegate is opening and closing OK.
Is there any device I can install in the pipework that will vent all boost above 1.5 bar (never reach this unless there is a problem)
Any help greatly appreciated.
Thanks
David
23 March 2004, 10:41 PM
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I will have a go at answering this but I am by no means an expert!
>>In neutral when you rev the engine does the wastegate open to limit boost.
In neutral there is no engine load so I think you can rev it all the way to the redline without it making boost. I think the ECU sees the rpm rising with throttle position so it doesn't close the wastegate.
>>If not is there anyway I can test the wastegate is opening and closing OK.
There should be a outlet nipple post turbo where a tube is connected that feeds the boost control solonoid. From the BCS there should be a tube that feeds the wastegate. Wastegates usually have a set pressure that they open at. In scoobs its 0.7bar which is the norm I believe for most wastegates. So if you bypass the BCS and connet the turbo outlet to the wastegate boost should be limited to 0.7 bar (or whatever your wastegate cracking pressure is). Get a boost gauge, bypass the BCS and lift off if you see over 1bar.
>>Is there any device I can install in the pipework that will vent all boost above 1.5 bar (never reach this unless there is a problem)
Yes, a Dawes device, its like a bleed valve but better. You bypass the BCS with this and set it to whatever boost you want. Again get a boost gauge, set the Dawes to open (wind the thread fully out) and the car will boost to the wastegate cracking pressure. Then wind it in a turn at a time and using the boost gauge keep noting the increase in boost untill you're happy.
hope this helps and I stand to be corrected.
>>In neutral when you rev the engine does the wastegate open to limit boost.
In neutral there is no engine load so I think you can rev it all the way to the redline without it making boost. I think the ECU sees the rpm rising with throttle position so it doesn't close the wastegate.
>>If not is there anyway I can test the wastegate is opening and closing OK.
There should be a outlet nipple post turbo where a tube is connected that feeds the boost control solonoid. From the BCS there should be a tube that feeds the wastegate. Wastegates usually have a set pressure that they open at. In scoobs its 0.7bar which is the norm I believe for most wastegates. So if you bypass the BCS and connet the turbo outlet to the wastegate boost should be limited to 0.7 bar (or whatever your wastegate cracking pressure is). Get a boost gauge, bypass the BCS and lift off if you see over 1bar.
>>Is there any device I can install in the pipework that will vent all boost above 1.5 bar (never reach this unless there is a problem)
Yes, a Dawes device, its like a bleed valve but better. You bypass the BCS with this and set it to whatever boost you want. Again get a boost gauge, set the Dawes to open (wind the thread fully out) and the car will boost to the wastegate cracking pressure. Then wind it in a turn at a time and using the boost gauge keep noting the increase in boost untill you're happy.
hope this helps and I stand to be corrected.
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