HELP: sudden gain in boost although it was cutting out?
06 July 2003, 05:55 PM
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Already posted in general technical but please leave here MODS need help 
Right car is me MY97 UK car with no serious engine mods or owt only real potential boost/performance related bits are blitz nurspec centre & back box (standard dp) & dump valve
Now previously with me defi HUD boost gauge i had achieved a max boost of 1.04 & this was when i had an ITG panel filter on, since had this replaced by standard panel filter at last service, hadn't noticed anything above 1 bar since.
However driving up motorway to a meet today when i planted my foot on the gas i noticed it shot up past 1 bar, after noticing this i tried again with sustained gas went upto about 1.15bar & then held at 1.14bar However it then started cutting out totally after about 2 seconds at this boost for a split second & then cut back into 1.14 or so again for a few secs & repeated...... Only did this a few times as it was v strange/worrying
On stopping to pick up some more peaps & popping bonnet nowt noticably looose or bizarre, other than a light bit of smoke from drivers side of engine which i already know to be a slightly leaking rocker gasket cover thingamy so surely unrelated
So carried onto meet with no excess accelerator use.....
On the way back i tested again & it seemed to now go upto around 1.12bar at most & hold this without any cutting out i only held this for 5 sex or so as i didnt fancy taking the pea untill i knew what the story was?
So any ideas why i have suddenly got extra boost & what the hell was the cutting out? IE is there anything going wrong that might cause this?
Just a gain in boost seems v weird
No changes in fuel or owt used always run on optimax & so er im flat outa ideas
HELP paranoia kicking in
Si
Right car is me MY97 UK car with no serious engine mods or owt only real potential boost/performance related bits are blitz nurspec centre & back box (standard dp) & dump valve
Now previously with me defi HUD boost gauge i had achieved a max boost of 1.04 & this was when i had an ITG panel filter on, since had this replaced by standard panel filter at last service, hadn't noticed anything above 1 bar since.
However driving up motorway to a meet today when i planted my foot on the gas i noticed it shot up past 1 bar, after noticing this i tried again with sustained gas went upto about 1.15bar & then held at 1.14bar However it then started cutting out totally after about 2 seconds at this boost for a split second & then cut back into 1.14 or so again for a few secs & repeated...... Only did this a few times as it was v strange/worrying
On stopping to pick up some more peaps & popping bonnet nowt noticably looose or bizarre, other than a light bit of smoke from drivers side of engine which i already know to be a slightly leaking rocker gasket cover thingamy so surely unrelated
So carried onto meet with no excess accelerator use.....On the way back i tested again & it seemed to now go upto around 1.12bar at most & hold this without any cutting out
i only held this for 5 sex or so as i didnt fancy taking the pea untill i knew what the story was?So any ideas why i have suddenly got extra boost & what the hell was the cutting out? IE is there anything going wrong that might cause this?
Just a gain in boost seems v weird
No changes in fuel or owt used always run on optimax & so er im flat outa ideas
HELP paranoia kicking in
Si
06 July 2003, 06:10 PM
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First off, by the time i have typed this someone else who types faster will have replied
The cutting out is a safety cut which is controlled by the ecu, when it senses that the boost has gone above a set limit (ie. 1.14bar) it cuts the fuel giving a sudden jolt (loss of power)
The reason it is intermittent is it only cuts fuel after boost has been above the threshhold for 5 secs, when it cuts the fuel it then instantly runs again... but if you hit boost level again it will cut again.. ie. teh rocking horse acceleration you are getting.
Next..
The first things you want to check are the pipes that run from the actuator to the turbo compressor housing and the pipe that T's off this pipe and runs to the boost solenoid.
If you are unsure of which part is what, post back..
R.
The cutting out is a safety cut which is controlled by the ecu, when it senses that the boost has gone above a set limit (ie. 1.14bar) it cuts the fuel giving a sudden jolt (loss of power)
The reason it is intermittent is it only cuts fuel after boost has been above the threshhold for 5 secs, when it cuts the fuel it then instantly runs again... but if you hit boost level again it will cut again.. ie. teh rocking horse acceleration you are getting.
Next..
The first things you want to check are the pipes that run from the actuator to the turbo compressor housing and the pipe that T's off this pipe and runs to the boost solenoid.
If you are unsure of which part is what, post back..
R.
06 July 2003, 06:35 PM
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Right that makes sense & while those parts do mean bugger all to me as a technical retard i am guna go to a fellow scooby owning mechanic who im sure that will mean sumin to
Ta
Si
& while those parts do mean bugger all to me as a technical retard i am guna go to a fellow scooby owning mechanic who im sure that will mean sumin to Ta
Si
06 July 2003, 07:29 PM
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Sorry mate been eatin...
The boost solenoid is the brass cylindrical object bolted onto a bracket on the drivers side supsension turret. it has a pipe going into it and a pipe coming out.
If you look at the pipe going into the top of the Boost solenoid and follow it backwards it is joined into the pipe that runs from the Actuator to the Compressor housing.
Sorry i havent got any pics on this PC.
R.
The boost solenoid is the brass cylindrical object bolted onto a bracket on the drivers side supsension turret. it has a pipe going into it and a pipe coming out.
If you look at the pipe going into the top of the Boost solenoid and follow it backwards it is joined into the pipe that runs from the Actuator to the Compressor housing.
Sorry i havent got any pics on this PC.
R.
06 July 2003, 07:31 PM
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A leak from one of these pipes would definately give you a boost increase.
There are another couple of things to try but you need to check the pipes out first, also check that none of the pipes have and splits or holes in (no matter how small)
R.
There are another couple of things to try but you need to check the pipes out first, also check that none of the pipes have and splits or holes in (no matter how small)
R.
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07 July 2003, 08:15 AM
#9
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Cheers for all that i will try & see if anything obvious later in the day & may get sum1 with more expertese to check it out
In the mean time thou stupid question, round 3, other than an obvious split or crack how can you tell where any leak might be as it's not exactly like a bicycle wheel that you can stick in a bowl of water & watch for bubbles?
Si
In the mean time thou stupid question, round 3, other than an obvious split or crack how can you tell where any leak might be as it's not exactly like a bicycle wheel that you can stick in a bowl of water & watch for bubbles?
Si
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