Wastegate Solnoid "Chatter"
16 November 1999, 07:06 PM
#1
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Can anyone advise me the best way to quieten the wategate soleniod on my MY97.
The device in question makes an annoying rattling noise under very light throttle or when pulling away. The noise is probably there all the time but is drown by engine/road noise at speed.
It's been bugging me for ages and my dealer finally identified it as the cause and claims "they all do it". Does anyone have any experience of a new one relieving the problem?
The technician said they have tried extra packing (rubber washers) where it secures to the suspension strut turret, and wrapping it in foam, both apparently help.
Any better ideas?
The device in question makes an annoying rattling noise under very light throttle or when pulling away. The noise is probably there all the time but is drown by engine/road noise at speed.
It's been bugging me for ages and my dealer finally identified it as the cause and claims "they all do it". Does anyone have any experience of a new one relieving the problem?
The technician said they have tried extra packing (rubber washers) where it secures to the suspension strut turret, and wrapping it in foam, both apparently help.
Any better ideas?
17 November 1999, 12:11 AM
#2
doesnt sound normal to me, however i have no scooby experience on this.
the solenoid is used to limit the boost and should only operate when the boost limit is reached.
I had the exact same problem on my cossie and it took me 2 months to find the reason.
It was caused in my case by the main earth connection on the ECU board having a dry joint. The problem was intermittent and would show up at different temperatures.
If you want a more detailed explanation let me know.
the solenoid is used to limit the boost and should only operate when the boost limit is reached.
I had the exact same problem on my cossie and it took me 2 months to find the reason.
It was caused in my case by the main earth connection on the ECU board having a dry joint. The problem was intermittent and would show up at different temperatures.
If you want a more detailed explanation let me know.
17 November 1999, 01:46 PM
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My 97 also makes this noise and very little can be done to reduce the rattle except wrapping in felt or other material. Isolating it with washers dos'nt help much since the noise is transmitted thru the air.
John
The solenoid operates almost all the time the engine is running. Boost is controlled by the duty cycle of solenoid pulses. If the solenoid only opened the wastegate at full boost the response would be too slow.
John
The solenoid operates almost all the time the engine is running. Boost is controlled by the duty cycle of solenoid pulses. If the solenoid only opened the wastegate at full boost the response would be too slow.
17 November 1999, 02:09 PM
#4
well, thats completely different to a cossie then.
Sounds a bizarre way to control boost.
How can my cossie cope with my config then.
On my rally car we use 2 fuel injectors to control the boost, they bypass air not fuel in this application, for fast response and controlability
Sounds a bizarre way to control boost.
How can my cossie cope with my config then.
On my rally car we use 2 fuel injectors to control the boost, they bypass air not fuel in this application, for fast response and controlability
18 November 1999, 11:05 PM
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Mark,
Unfortunately they do "all do that" pretty much. This method of boost control is used for the majority of modern ECU controlled turbos - it's unfortunate that Subaru fit a cheap and noisy one! I believe later cars use a rubber mount to stop the noise transmission through the bodywork - so apart from doing that and wrapping sound proofing around it, there's not that much that can be done simply. Of course a more intelligent boost control algorithm would solve the problem...
Unfortunately they do "all do that" pretty much. This method of boost control is used for the majority of modern ECU controlled turbos - it's unfortunate that Subaru fit a cheap and noisy one! I believe later cars use a rubber mount to stop the noise transmission through the bodywork - so apart from doing that and wrapping sound proofing around it, there's not that much that can be done simply. Of course a more intelligent boost control algorithm would solve the problem...
16 March 2000, 01:00 PM
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guys, I'm trying to follow this thread thru.
My sti too has this flapping chatter on very light throttle say idle to 12OO rpm, the engine noise then drowns out the chatter.
Could this solenoid problem be associated with the engine oil overfilling, - solenoid problem as I discovered via IWOC.
If so can the contamination be cleared by cleaning out the solenoid ?
Cheers
Howie
[This message has been edited by H@work (edited 16-03-2000).]
My sti too has this flapping chatter on very light throttle say idle to 12OO rpm, the engine noise then drowns out the chatter.
Could this solenoid problem be associated with the engine oil overfilling, - solenoid problem as I discovered via IWOC.
If so can the contamination be cleared by cleaning out the solenoid ?
Cheers
Howie
[This message has been edited by H@work (edited 16-03-2000).]
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16 March 2000, 01:49 PM
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John,
As I understand it, the Impreza boost control system is designed so that the ECU has to pulse the boost control solenoid in order to bleed the wastegate feed off in order to increase the boost over a mechanically set safe limit. If the solenoid were to fail, the car would still be able to boost to the safe limit of it's mechanical feedback system, say 7psi. This makes for a safe feedback system that will survive failure of it's control hardware.
If your cossie were to suffer a failure in it's boost control solenoid/fuel injector, would that mean saying bye bye to that lovely group A engine?
Moray
As I understand it, the Impreza boost control system is designed so that the ECU has to pulse the boost control solenoid in order to bleed the wastegate feed off in order to increase the boost over a mechanically set safe limit. If the solenoid were to fail, the car would still be able to boost to the safe limit of it's mechanical feedback system, say 7psi. This makes for a safe feedback system that will survive failure of it's control hardware.
If your cossie were to suffer a failure in it's boost control solenoid/fuel injector, would that mean saying bye bye to that lovely group A engine?
Moray
16 March 2000, 05:57 PM
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Howie,
I don't believe the noise is anything to do with overfilling the engine with oil. That will give you the spoof overboost problem and cut the fueling/ignition, leading to some interesting overtaking experiences.
I convinced my dealer to fit a new solenoid anyway and the new one is much quieter. The noise is still there but you really have to listen for it now.
I don't believe the noise is anything to do with overfilling the engine with oil. That will give you the spoof overboost problem and cut the fueling/ignition, leading to some interesting overtaking experiences.
I convinced my dealer to fit a new solenoid anyway and the new one is much quieter. The noise is still there but you really have to listen for it now.
17 March 2000, 09:57 PM
#10
nope, our engine is well hard 
The main reason the two injectors are used is in the very fast response for the ALS system.
I have knackered a turbo on my road car cossie once when the pipe came off the solenoid so the impreza idea is probably a good one for a road car.
The main reason the two injectors are used is in the very fast response for the ALS system.
I have knackered a turbo on my road car cossie once when the pipe came off the solenoid so the impreza idea is probably a good one for a road car.
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