Turbo pulsating on full boost
20 June 2001, 09:07 PM
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Does anyone have the same problem or an answer to this one?
We have a 96 WRX which under full boost seems to pulsate on and off (ie in and out of boost). I have changed the clutch, given full service repaired speedo cable which was slipping, but to no avail. Someone please help me. Thank you in anticipation of ....
Scott
We have a 96 WRX which under full boost seems to pulsate on and off (ie in and out of boost). I have changed the clutch, given full service repaired speedo cable which was slipping, but to no avail. Someone please help me. Thank you in anticipation of ....
Scott
20 June 2001, 09:37 PM
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Scott.
If it's a very abrupt loss of power which comes back in again very abrubtly it sounds like overboost. Do a search and you'll find loads of threads about it and how to cure it.
Stef.
If it's a very abrupt loss of power which comes back in again very abrubtly it sounds like overboost. Do a search and you'll find loads of threads about it and how to cure it.
Stef.
20 June 2001, 09:41 PM
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No its VERY SLIGHT <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Stef:
<B>Scott.
If it's a very abrupt loss of power which comes back in again very abrubtly it sounds like overboost. Do a search and you'll find loads of threads about it and how to cure it.
Stef.[/quote]
<B>Scott.
If it's a very abrupt loss of power which comes back in again very abrubtly it sounds like overboost. Do a search and you'll find loads of threads about it and how to cure it.
Stef.[/quote]
20 June 2001, 10:19 PM
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I have no idea what could be causing it, but I would like to know the symptoms. Can you feel it or is it only sound? Does it happen under full throttle or part throttle?
Sometimes if an aftermarket blow off valve is fitted and it starts to stick due to moisture, it can cause pulsating. If this is the cause, pull the blow off valve appart and clean it with WD40 and a rag. Do not machine it or use sandpaper to clean it.
WREXY
P.S. Don't forget to answer my symptom questions please Scott.
Sometimes if an aftermarket blow off valve is fitted and it starts to stick due to moisture, it can cause pulsating. If this is the cause, pull the blow off valve appart and clean it with WD40 and a rag. Do not machine it or use sandpaper to clean it.
WREXY
P.S. Don't forget to answer my symptom questions please Scott.
20 June 2001, 10:50 PM
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Greenman,
I experienced a similar problem on my MY00 last week, when I fitted a replacement brass restrictor in the wastgate actuator pipe, with a 0.9mm bore (same as a P1, which boosts to 15.95psi) in lieu of the standard 1.15mm bore, which should give 13.1psi on a UK car.
My car actually peaks at 14.3psi and holds 13.8psi with the std restrictor in place.
Peak boost went up th 17.3psi but under full load the boost came in then died and kept repeating.
I increased the restrictor bore size to 1mm and it lessened the severity, but it was still present.
I eventually replaced my home made restrictor with the factory fit item, and everything cleared up.
So the point I am getting at, is possibly the pipework/restrictor on your car may becoming blocked, leading to the symptoms I encountered.
The restricor is fitted in the small rubber tubing leading from the wastegate actuator, going to the metal tube sticking out of the turbo outlet to the intercooler.
It is in the section of pipe immediately after the 'T' piece.
The bottom leg of the 'T' leads to the wastgate solenoid on the inner wing.
The restrictor measures 0.175" diameter and is 0.237" in length with a 1mm dia approx hole in it, so it is a SMALL item, don't lose it.
My local dealer doesn't stock them, and I doubt many of them do, and your car will not run properly without it.
Suggest remove this small section of pipe, and use the WD40 on this as well.
Cheers MTR
I experienced a similar problem on my MY00 last week, when I fitted a replacement brass restrictor in the wastgate actuator pipe, with a 0.9mm bore (same as a P1, which boosts to 15.95psi) in lieu of the standard 1.15mm bore, which should give 13.1psi on a UK car.
My car actually peaks at 14.3psi and holds 13.8psi with the std restrictor in place.
Peak boost went up th 17.3psi but under full load the boost came in then died and kept repeating.
I increased the restrictor bore size to 1mm and it lessened the severity, but it was still present.
I eventually replaced my home made restrictor with the factory fit item, and everything cleared up.
So the point I am getting at, is possibly the pipework/restrictor on your car may becoming blocked, leading to the symptoms I encountered.
The restricor is fitted in the small rubber tubing leading from the wastegate actuator, going to the metal tube sticking out of the turbo outlet to the intercooler.
It is in the section of pipe immediately after the 'T' piece.
The bottom leg of the 'T' leads to the wastgate solenoid on the inner wing.
The restrictor measures 0.175" diameter and is 0.237" in length with a 1mm dia approx hole in it, so it is a SMALL item, don't lose it.
My local dealer doesn't stock them, and I doubt many of them do, and your car will not run properly without it.
Suggest remove this small section of pipe, and use the WD40 on this as well.
Cheers MTR
20 June 2001, 10:55 PM
#6
Ecu Specialist
Sounds like someone has taken the restrictor out of the solenoid vent pipe (lower vertical exit) which is, or should be , positioned just inside the solenoid end, check and see, if its missing then this could be causing the problem as the ecu will not be able to catch up with the boost enough to control it. On cars up to MY96 the restrictor has a different function to the later items.
The restrictor in your car is totally different to the later models as described and is not in the same place but where I have indicated. You also have a three port solenoid as standard not a two port. the restrictor needed is 2.0mm bore and is larger than the later ones, if its missing mail me and I will give you the part number that you need.
The restrictor in your car is totally different to the later models as described and is not in the same place but where I have indicated. You also have a three port solenoid as standard not a two port. the restrictor needed is 2.0mm bore and is larger than the later ones, if its missing mail me and I will give you the part number that you need.
20 June 2001, 11:22 PM
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Bob,
From your comments am I correct in assuming that is what was happening to my car.
It pulled like a train, then died as though suffering from fuel starvation, (like empty float chamber syndrome on a carburated engine when running too small a needle valve), then pulled like stink again.
The select monitor was showing 17psi+ peak boost momentarily, but I couldn't get a reading under load due to traffic, and the on/off characteristics of the engine.
It don't think it was overboost, as it only hit 17psi for a very short time, and the Subaru mechanic tells me fuel cut is at 17.4psi.
Cheers MTR
From your comments am I correct in assuming that is what was happening to my car.
It pulled like a train, then died as though suffering from fuel starvation, (like empty float chamber syndrome on a carburated engine when running too small a needle valve), then pulled like stink again.
The select monitor was showing 17psi+ peak boost momentarily, but I couldn't get a reading under load due to traffic, and the on/off characteristics of the engine.
It don't think it was overboost, as it only hit 17psi for a very short time, and the Subaru mechanic tells me fuel cut is at 17.4psi.
Cheers MTR
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21 June 2001, 03:55 AM
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If its not boost cut protection, then make sure your fuel tank is no less than 3/4 full and see if this still happens. Does this happens especially when turning at right hand corner at speed?
Hyper
Hyper
22 June 2001, 08:56 PM
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HI sorry I tock so long to get back !
It happens under part throttle .BUT only if u press the throttle down slowly.
It happened before and after a new dump valve was fitted. Any idea??????????????????? <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by WREXY:
<B>I have no idea what could be causing it, but I would like to know the symptoms. Can you feel it or is it only sound? Does it happen under full throttle or part throttle?
Sometimes if an aftermarket blow off valve is fitted and it starts to stick due to moisture, it can cause pulsating. If this is the cause, pull the blow off valve appart and clean it with WD40 and a rag. Do not machine it or use sandpaper to clean it.
WREXY
P.S. Don't forget to answer my symptom questions please Scott.[/quote]
It happens under part throttle .BUT only if u press the throttle down slowly.
It happened before and after a new dump valve was fitted. Any idea??????????????????? <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by WREXY:
<B>I have no idea what could be causing it, but I would like to know the symptoms. Can you feel it or is it only sound? Does it happen under full throttle or part throttle?
Sometimes if an aftermarket blow off valve is fitted and it starts to stick due to moisture, it can cause pulsating. If this is the cause, pull the blow off valve appart and clean it with WD40 and a rag. Do not machine it or use sandpaper to clean it.
WREXY
P.S. Don't forget to answer my symptom questions please Scott.[/quote]
22 June 2001, 09:07 PM
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No it happens all the time under half throttle ! <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Hyperex:
<B>If its not boost cut protection, then make sure your fuel tank is no less than 3/4 full and see if this still happens. Does this happens especially when turning at right hand corner at speed?
Hyper[/quote]
<B>If its not boost cut protection, then make sure your fuel tank is no less than 3/4 full and see if this still happens. Does this happens especially when turning at right hand corner at speed?
Hyper[/quote]
22 June 2001, 09:19 PM
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THANKS I WILL HAVE A LOOK AND GET BACK TO U.
SCOTT <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by MTR:
<B>Greenman,
I experienced a similar problem on my MY00 last week, when I fitted a replacement brass restrictor in the wastgate actuator pipe, with a 0.9mm bore (same as a P1, which boosts to 15.95psi) in lieu of the standard 1.15mm bore, which should give 13.1psi on a UK car.
My car actually peaks at 14.3psi and holds 13.8psi with the std restrictor in place.
Peak boost went up th 17.3psi but under full load the boost came in then died and kept repeating.
I increased the restrictor bore size to 1mm and it lessened the severity, but it was still present.
I eventually replaced my home made restrictor with the factory fit item, and everything cleared up.
So the point I am getting at, is possibly the pipework/restrictor on your car may becoming blocked, leading to the symptoms I encountered.
The restricor is fitted in the small rubber tubing leading from the wastegate actuator, going to the metal tube sticking out of the turbo outlet to the intercooler.
It is in the section of pipe immediately after the 'T' piece.
The bottom leg of the 'T' leads to the wastgate solenoid on the inner wing.
The restrictor measures 0.175" diameter and is 0.237" in length with a 1mm dia approx hole in it, so it is a SMALL item, don't lose it.
My local dealer doesn't stock them, and I doubt many of them do, and your car will not run properly without it.
Suggest remove this small section of pipe, and use the WD40 on this as well.
Cheers MTR[/quote]
SCOTT <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by MTR:
<B>Greenman,
I experienced a similar problem on my MY00 last week, when I fitted a replacement brass restrictor in the wastgate actuator pipe, with a 0.9mm bore (same as a P1, which boosts to 15.95psi) in lieu of the standard 1.15mm bore, which should give 13.1psi on a UK car.
My car actually peaks at 14.3psi and holds 13.8psi with the std restrictor in place.
Peak boost went up th 17.3psi but under full load the boost came in then died and kept repeating.
I increased the restrictor bore size to 1mm and it lessened the severity, but it was still present.
I eventually replaced my home made restrictor with the factory fit item, and everything cleared up.
So the point I am getting at, is possibly the pipework/restrictor on your car may becoming blocked, leading to the symptoms I encountered.
The restricor is fitted in the small rubber tubing leading from the wastegate actuator, going to the metal tube sticking out of the turbo outlet to the intercooler.
It is in the section of pipe immediately after the 'T' piece.
The bottom leg of the 'T' leads to the wastgate solenoid on the inner wing.
The restrictor measures 0.175" diameter and is 0.237" in length with a 1mm dia approx hole in it, so it is a SMALL item, don't lose it.
My local dealer doesn't stock them, and I doubt many of them do, and your car will not run properly without it.
Suggest remove this small section of pipe, and use the WD40 on this as well.
Cheers MTR[/quote]
24 June 2001, 10:19 AM
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I DONT HAVE A (EBC?) I ALSO DONT NO WHAT BOOST IM RUNNING BUT GETTING BOOST GAUGE. <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Hyperex:
<B>What boost pressure are you running? Do you have a EBC to control the boost? If yes, lower down you boost bit by bit to see if it still happpens.[/quote]
<B>What boost pressure are you running? Do you have a EBC to control the boost? If yes, lower down you boost bit by bit to see if it still happpens.[/quote]
24 June 2001, 04:40 PM
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Electronic Boost Controller. Suggest u install one (some hv function of boost guage). Might not cure ur problem but always good to hv one, if u ever intend to modify ur car in any stage.
24 June 2001, 06:13 PM
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Thanks, any idea which one to get and from where? Many thanks scott <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Hyperex:
<B>Electronic Boost Controller. Suggest u install one (some hv function of boost guage). Might not cure ur problem but always good to hv one, if u ever intend to modify ur car in any stage.[/quote]
<B>Electronic Boost Controller. Suggest u install one (some hv function of boost guage). Might not cure ur problem but always good to hv one, if u ever intend to modify ur car in any stage.[/quote]
24 June 2001, 06:48 PM
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Install this !!! very accurate, can't go wrong.
Blitz SBC-ID (Controll Boost and have Boost indicator, shows ur boost pressure like the boost guage)
Better still, install this too.
Blitz Power-ID, works in conjuction with the SBC-ID. Can show your accerate speed like 0-100km/h, 0-160 km/h, 1/4 mile time, etc. Also shows the HP of the car (kw, ps, hp) in different boost pressure, its a simulator, about 90% accuracy, from my experience (this is the main function of this Power-ID meter).
Maybe able to get it from Racelogic, if i'm not wrong.
Hyperex
Blitz SBC-ID (Controll Boost and have Boost indicator, shows ur boost pressure like the boost guage)
Better still, install this too.
Blitz Power-ID, works in conjuction with the SBC-ID. Can show your accerate speed like 0-100km/h, 0-160 km/h, 1/4 mile time, etc. Also shows the HP of the car (kw, ps, hp) in different boost pressure, its a simulator, about 90% accuracy, from my experience (this is the main function of this Power-ID meter).
Maybe able to get it from Racelogic, if i'm not wrong.
Hyperex
24 June 2001, 09:03 PM
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THANK U VERY MUCH <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Hyperex:
<B>Install this !!! very accurate, can't go wrong.
Blitz SBC-ID (Controll Boost and have Boost indicator, shows ur boost pressure like the boost guage)
Better still, install this too.
Blitz Power-ID, works in conjuction with the SBC-ID. Can show your accerate speed like 0-100km/h, 0-160 km/h, 1/4 mile time, etc. Also shows the HP of the car (kw, ps, hp) in different boost pressure, its a simulator, about 90% accuracy, from my experience (this is the main function of this Power-ID meter).
Maybe able to get it from Racelogic, if i'm not wrong.
Hyperex
[/quote]
<B>Install this !!! very accurate, can't go wrong.
Blitz SBC-ID (Controll Boost and have Boost indicator, shows ur boost pressure like the boost guage)
Better still, install this too.
Blitz Power-ID, works in conjuction with the SBC-ID. Can show your accerate speed like 0-100km/h, 0-160 km/h, 1/4 mile time, etc. Also shows the HP of the car (kw, ps, hp) in different boost pressure, its a simulator, about 90% accuracy, from my experience (this is the main function of this Power-ID meter).
Maybe able to get it from Racelogic, if i'm not wrong.
Hyperex
[/quote]
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