Loss of power (cut out) when changing gear
26 November 2002, 03:53 PM
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When i am accelerating hard in first gear, upon changing to second (and sometimes second to third)and hitting the accelerator again i experience some sort of cut-out when the clutch is released, but it only lasts for a very short time (about half a second or less). Anyone got any ideas please???? I have a `99 V-reg turbo 2000. Cheers
[Edited by Abbylad - 11/26/2002 6:49:17 PM]
[Edited by Abbylad - 11/26/2002 6:49:17 PM]
27 November 2002, 12:41 PM
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Abbeylad,
I've had a similar problem on my MY99 turbo when taking the revs to about 6k before changing up. I dunno what it is, but driving style seems to affect it. I now change gear more slowly and I never see the problem.
It annoys me, coz when you're giving it some welly, that's when you want to do fast gear changes. Takes some of the fun out of my Scoob.
I've had Subaru replace the MAF under warranty (no difference). I think they mis-diagnosed the problem. I also had some wastegate restrictor pipe (I think that's what it's called???) changed. Still drives the same.
You're not alone.
Cheers
Stu
I've had a similar problem on my MY99 turbo when taking the revs to about 6k before changing up. I dunno what it is, but driving style seems to affect it. I now change gear more slowly and I never see the problem.
It annoys me, coz when you're giving it some welly, that's when you want to do fast gear changes. Takes some of the fun out of my Scoob.
I've had Subaru replace the MAF under warranty (no difference). I think they mis-diagnosed the problem. I also had some wastegate restrictor pipe (I think that's what it's called???) changed. Still drives the same.
You're not alone.
Cheers
Stu
27 November 2002, 01:12 PM
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My MY00 has also done this from new - dealer basically told me to drive around it by either changing gear before reaching 6k or to slip the clutch slightly on re-engaging (which seems to work, but not sure about the clutch's life!).
If anyone's found an answer, I'd love to know.
Dave
If anyone's found an answer, I'd love to know.
Dave
27 November 2002, 05:25 PM
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Thanks for your replies, feel better knowing i haven`t bought a dog. Yeah it is doing it when i`m above 6k rpm. I`ve been doing some `research` on this and found the following paragraph on the Subaru Impreza Drivers Club FAQ page, see what you think:-
3.2 Waste gate solenoid
The 1997 specification lowered the turbo boost pressure from 1.0 bar to 0.9 bar. The engine breather system vents into the air intake and it is possible for the oil and condensing, burnt oil vapours build up in this valve. This valve is a safety device for detecting overboost and will cause fuel and ignition to be cut if it senses that 1.2bar (97/98 models) has been reached. If it is bunged up, it isn't sensing correctly and will shut down the engine under high boost conditions. The solution advised by Subaru France was not to fill the oil up to maximum but to leave it at half filled only.
If your wastegate solenoid does pack up, the fix is to pull the T shaped supply hose off and fill it with brake cleaner from an aerosol. Then go for a blast before the cleaner evaporates. Tippex thinners also do the job. '98 models have a revised part, which is three port sensing and there have been no reported failures. You can get '97 cars upgraded.
Apparently the fault often occurs just after a service when the oil level may be slightly too high. The 1998 specification engine apparently has revised sensing locations, to over come the above problems but there have been some reports of failure on early '98s.
Sometimes this fault is incorrectly termed as "over boosting". The sensor is designed to detect an over boost situation and is usually so sensitive in normal operation that 1.19bar = ok and 1.20bar = fuel cut routine due to over boost. When it becomes contaminated by oil, this is lost and the sensor can cut in at much lower boost values, cutting in the routine under normal hard acceleration. The effect of this routine is quite disconcerting as all engine power is suddenly lost with some drivers reporting it feeling as if they have just driven into a brick wall!
Sent an e-mail to a bloke called Pete Croney at the SIDC about my car and he says if it is this problem (and it sounds like it is) then its covered under the warranty. Got mine booked in for a going over next tuesday so keep watching this space.
Cheers
[Edited by Abbylad - 11/27/2002 5:29:06 PM]
3.2 Waste gate solenoid
The 1997 specification lowered the turbo boost pressure from 1.0 bar to 0.9 bar. The engine breather system vents into the air intake and it is possible for the oil and condensing, burnt oil vapours build up in this valve. This valve is a safety device for detecting overboost and will cause fuel and ignition to be cut if it senses that 1.2bar (97/98 models) has been reached. If it is bunged up, it isn't sensing correctly and will shut down the engine under high boost conditions. The solution advised by Subaru France was not to fill the oil up to maximum but to leave it at half filled only.
If your wastegate solenoid does pack up, the fix is to pull the T shaped supply hose off and fill it with brake cleaner from an aerosol. Then go for a blast before the cleaner evaporates. Tippex thinners also do the job. '98 models have a revised part, which is three port sensing and there have been no reported failures. You can get '97 cars upgraded.
Apparently the fault often occurs just after a service when the oil level may be slightly too high. The 1998 specification engine apparently has revised sensing locations, to over come the above problems but there have been some reports of failure on early '98s.
Sometimes this fault is incorrectly termed as "over boosting". The sensor is designed to detect an over boost situation and is usually so sensitive in normal operation that 1.19bar = ok and 1.20bar = fuel cut routine due to over boost. When it becomes contaminated by oil, this is lost and the sensor can cut in at much lower boost values, cutting in the routine under normal hard acceleration. The effect of this routine is quite disconcerting as all engine power is suddenly lost with some drivers reporting it feeling as if they have just driven into a brick wall!
Sent an e-mail to a bloke called Pete Croney at the SIDC about my car and he says if it is this problem (and it sounds like it is) then its covered under the warranty. Got mine booked in for a going over next tuesday so keep watching this space.
Cheers
[Edited by Abbylad - 11/27/2002 5:29:06 PM]
27 November 2002, 05:55 PM
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Don't want to p1ss on your bonfire, but my dealer replaced the boost control solenoid, with no effect. I certainly think it feels like a fuel cut caused by a momentary overboost, but can't prove it. Somebody (can't remember who) emailed me a Delta Dash log of their car during a gear change where this "power cut" occurred, but there was no sign of a boost spike or a fuel cut (would have expected to see the injector duty cycle to go to zero briefly). So no help there...
I'm still mystified and now just drive around the problem - not ideal on a car I paid £20k for.
Dave
I'm still mystified and now just drive around the problem - not ideal on a car I paid £20k for.
Dave
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27 November 2002, 06:19 PM
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I think this is a "feature" of at least the MY99/00 and probably others.
Mine does it - you see it on 7000 RPM gear changes if you rush then on a g trace - momentary cut of g when re-engaging the clutch at the end of the change.
Mine does it - you see it on 7000 RPM gear changes if you rush then on a g trace - momentary cut of g when re-engaging the clutch at the end of the change.
but mainly very good I'm pleased to say
27 November 2002, 08:19 PM
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Right, when i had this on my 1st MY99 it was not the boost solenoid, it was actually the wastegate jamming open, then suddenley closing once power began to rise.
Can only assume it was sticking on something. I took the downpipe off and had a good look around, nothing obvious, although there seemed to be quite a bit of vertical movement in the wastegate.
Anyway, put the downpipe back on, and it never did it again. Puzzled me
Can only assume it was sticking on something. I took the downpipe off and had a good look around, nothing obvious, although there seemed to be quite a bit of vertical movement in the wastegate.
Anyway, put the downpipe back on, and it never did it again. Puzzled me
28 November 2002, 02:01 PM
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Steve
Not saying that that isn't the cause of the problem, but I would have expected to see some evidence of this on a Delta Dash plot. Also, if the wastegate stuck open momentarily, I wouldn't have thought that it would feel like such a total power cut - more like a "holding back" than the "total fuel cut" feeling I get on mine.
John - have you managed to spot any evidence from Delta Dash as to what actually causes it. I have never driven any other car which does this, and it does require some effort/thought to drive around it.
Dave
Not saying that that isn't the cause of the problem, but I would have expected to see some evidence of this on a Delta Dash plot. Also, if the wastegate stuck open momentarily, I wouldn't have thought that it would feel like such a total power cut - more like a "holding back" than the "total fuel cut" feeling I get on mine.
John - have you managed to spot any evidence from Delta Dash as to what actually causes it. I have never driven any other car which does this, and it does require some effort/thought to drive around it.
Dave
28 November 2002, 02:12 PM
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With mine, and i am being serious, my boost would it in excess of 25psi on the gauge, and that would be fuel cut in my eyes. However some times it would hit normal boost and then on lift off to change gear i would have a major loss of power, not quite as violent as fuel cut.
Sometimes it was like a bloody seasaw, overboost (but not fuel cut level), then selenoid pics up and wastegate opens, but due to excess boost? it opens hard and gets stuck, giving a similar feeling to fuel cut.
Thats what i put mine down to anyway
Sometimes it was like a bloody seasaw, overboost (but not fuel cut level), then selenoid pics up and wastegate opens, but due to excess boost? it opens hard and gets stuck, giving a similar feeling to fuel cut.
Thats what i put mine down to anyway
28 November 2002, 02:20 PM
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My MY00 has done this a lot less since changing the downpipe to scoobysport one.
<speculation>
The standard exhaust has the wastegate blocked off. The scoobysport is open neck. Could the excess air on the turbo be causing overboost briefly when the engine is loaded again?
</speculation>
<speculation>
The standard exhaust has the wastegate blocked off. The scoobysport is open neck. Could the excess air on the turbo be causing overboost briefly when the engine is loaded again?
</speculation>
28 November 2002, 03:19 PM
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4th gear!!! If only I had known.....maybe my fuel economy will improve!!
The problem seems worst 2nd to 3rd. Only happens occasionally 3rd to 4th....but I never get the chance to test that because I don't want to do over 6000rpm in 3rd because - I might be breaking the law.
The problem seems worst 2nd to 3rd. Only happens occasionally 3rd to 4th....but I never get the chance to test that because I don't want to do over 6000rpm in 3rd because - I might be breaking the law.
28 November 2002, 04:37 PM
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Could be - though it's done it from new and currently only has 21k miles.
Something "sticking" does seem a likely candidate - I did suspect the dump valve (tho' never followed this up) but a sticking actuator makes more sense.
Think I'd like somebody to come up with something conclusive before I start merrily changing bits - strikes me as one of those problems you could throw a lot of money at and not solve.
It does only seem to be phase 2 classics afflicted by this - don't know if there's any conclusions can be drawn from this?
Dave
Something "sticking" does seem a likely candidate - I did suspect the dump valve (tho' never followed this up) but a sticking actuator makes more sense.
Think I'd like somebody to come up with something conclusive before I start merrily changing bits - strikes me as one of those problems you could throw a lot of money at and not solve.
It does only seem to be phase 2 classics afflicted by this - don't know if there's any conclusions can be drawn from this?
Dave