Overboosting
09 September 2002, 05:30 PM
#2
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my limited knowledge of such things (compresses air, car goes faster) leads me to tell you that overboost is caused where the turbo is too big for your engine, so it's creating more boost than you can use. So your engine will redline before the turbo is running at maximum boost. You are therefore not getting the full benefit of your turbo as you're not using all the boost. You have overboost.
09 September 2002, 07:35 PM
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Having suffered this problem when modifying me scoob 
It basically occurs when you hit the safety boost cut off, ie 19psi for instance, its a safety device built into the ecu stopping you blowing your engine up but overboosting is caused by the ammount of pressure and quicker spool up times and less resistance (or the likes there of)
John Banks should be able to explain it better, it normally occurs in colder parts of the year though and normally in 4th and 5th gear.
Depending on which type of turbo you have (as the bigger turbos on the older cars have a bit more of an affect, ie pull yourself off your windscreen type affect) but if you do get it, it feels like pulsing, on off on off etc.
Tony
It basically occurs when you hit the safety boost cut off, ie 19psi for instance, its a safety device built into the ecu stopping you blowing your engine up but overboosting is caused by the ammount of pressure and quicker spool up times and less resistance (or the likes there of)
John Banks should be able to explain it better, it normally occurs in colder parts of the year though and normally in 4th and 5th gear.
Depending on which type of turbo you have (as the bigger turbos on the older cars have a bit more of an affect, ie pull yourself off your windscreen type affect) but if you do get it, it feels like pulsing, on off on off etc.
Tony
09 September 2002, 09:42 PM
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This sounds like you have a concern and have been told it is caused by overboosting. I had this on my MY98 where the sensor was picking up dirt and causing the car to judder when under boost. Ask someone to clean it, or do it yourself and it will not do it again. There is probably a thread on cleaning the sensor here somewhere...
09 October 2002, 02:44 PM
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Sounds like coilpacks to me.
At 1.2 bar with a FCD fitted there is no way you should be hitting the ECU fuel cut so I doubt very much that it is the cause. Wind your FCD down to 1 and if it still does it, it isn't overboost.
YHM m8
Rich
[Edited by RICH WILD - 9/10/2002 2:46:32 PM]
At 1.2 bar with a FCD fitted there is no way you should be hitting the ECU fuel cut so I doubt very much that it is the cause. Wind your FCD down to 1 and if it still does it, it isn't overboost.
YHM m8
Rich
[Edited by RICH WILD - 9/10/2002 2:46:32 PM]
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