1.7 bar boost spikes on new STI7
10 April 2002, 12:18 PM
#1
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Hi all
seen a few mentions of the above on a decat version.
Can someone explain to me how/why this happens and what effect it has on the car?
DaveTS is prob a bit of an expert on it.
Dave?
Cheers
jas
seen a few mentions of the above on a decat version.
Can someone explain to me how/why this happens and what effect it has on the car?
DaveTS is prob a bit of an expert on it.
Dave?
Cheers
jas
10 April 2002, 12:43 PM
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Probably best asking this is in the drivetrain section but from what I have read there doesnt seem to be a cure at the moment so I guess you wont get many informed replies.
10 April 2002, 12:56 PM
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10 April 2002, 01:40 PM
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Basically yes. It's when the turbine spins up too fast before the boost control can get hold of it and pull it back to the table in the ECU.
If you watch it on a boost gauge whils driving the car under load in a higher gear, you will see when the turbo spins up the boost gauge will momentarily peak, or spike, at, say, 1.7 bar, then rapidly (in a second or two) drop back to the held figure of 1.15 or so when the ECU gets hold of it and gets the boost control solenoid to operate the wastegate.
The restrictor is in the pipe from the compressor to the boost control solenoid, and basically controls how quick the solenoid responds by how much air can flow through the hole in the restrictor.
It has been said that the initial boost spike on an STi7 can be brought down to a safe figure by just changing the restrictor to one with a bigger hole in, but almost everyone that has actually tried this says it does not bring the spike back to a safe level with just a change of restrictor.
If you watch it on a boost gauge whils driving the car under load in a higher gear, you will see when the turbo spins up the boost gauge will momentarily peak, or spike, at, say, 1.7 bar, then rapidly (in a second or two) drop back to the held figure of 1.15 or so when the ECU gets hold of it and gets the boost control solenoid to operate the wastegate.
The restrictor is in the pipe from the compressor to the boost control solenoid, and basically controls how quick the solenoid responds by how much air can flow through the hole in the restrictor.
It has been said that the initial boost spike on an STi7 can be brought down to a safe figure by just changing the restrictor to one with a bigger hole in, but almost everyone that has actually tried this says it does not bring the spike back to a safe level with just a change of restrictor.
10 April 2002, 01:58 PM
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LOL
I can well imagine
How are you finding the STI?
I like them but have only had my WRSprt RB5 for a year.
love it to bits and will prob keep it for at least another 18 months and then who knows....
I can well imagine
How are you finding the STI?
I like them but have only had my WRSprt RB5 for a year.
love it to bits and will prob keep it for at least another 18 months and then who knows....
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