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Author possible causes of not holding boost
SteveW
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Registered: 15th Jul 02
Location: Up in the clouds
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11th Aug 05 at 11:32   View User's Profile U2U Member Reply With Quote
right i was giving the car a little blat around last night.. when i noticed it wasnt holding boost when i was in "Phase 2" mode

clicked on the button and it overboosted to 20psi which is normal, then held at 16psi which it should, then it just started to drop and drop until it was back to 10

dunno what might be causing this but its anoying.. bad thing is it doesnt happen all the time either !


please help

Steve
Ditch
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Registered: 29th Nov 02
Location: St Albans Drives: JDM Celica GT4 WRC
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11th Aug 05 at 11:33   View User's Profile U2U Member Reply With Quote
worn wastegate???

split pipe - would do it all the time though?
ed
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Registered: 10th Sep 03
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11th Aug 05 at 11:34   View User's Profile U2U Member Reply With Quote
Shit car?
ed
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Registered: 10th Sep 03
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11th Aug 05 at 11:35   View User's Profile U2U Member Reply With Quote
Get proper engine management instead of that silly EDS stuff
Stu
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Registered: 3rd May 00
Location: Madchester UK Drives: 2014 BMW M135i
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11th Aug 05 at 11:35   View User's Profile U2U Member Reply With Quote
Wastegate, actuator, tired turbo, faulty boost controller, ECU cutting boost, leak.........loads of em really!
SteveW
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11th Aug 05 at 11:47   View User's Profile U2U Member Reply With Quote
ed - shut it and go jump in a river

well its not the turbo or wastegate.. thats for sure

as for boost controller ? not sure bout that one, sound the most realistic

oh and its not gonna bea asplit hose either, had all them checked the other day
Rupean
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Registered: 24th Dec 03
Location: Leicester
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11th Aug 05 at 11:54   View User's Profile U2U Member Reply With Quote
Phase 2 Holds 14psi not 16psi and Should Overboost to 19psi. just throught id let u know.
Teddy
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Registered: 19th Jul 04
Location: Northampton Drives: VW Bora 1.9TDi pd130
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11th Aug 05 at 11:57   View User's Profile U2U Member Reply With Quote
You still running an amal valve?
SteveW
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Registered: 15th Jul 02
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11th Aug 05 at 11:58   View User's Profile U2U Member Reply With Quote
oh OK..

well 1psi out on the overboost.. thats fine

but it shouldnt drop lower than 13-14psi really.. it hold until the revs get really high, thats when it starts trailing off
AK
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Registered: 5th Jul 00
Location: Aberdeen City
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11th Aug 05 at 12:00   View User's Profile U2U Member Reply With Quote
is it running a bleed valve? dawes type?
Teddy
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Registered: 19th Jul 04
Location: Northampton Drives: VW Bora 1.9TDi pd130
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11th Aug 05 at 12:05   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by SteveW
oh OK..

well 1psi out on the overboost.. thats fine

but it shouldnt drop lower than 13-14psi really.. it hold until the revs get really high, thats when it starts trailing off


Right so its overboosting when you nail it. Thats fine.
Its holding roughly the right boost (obviously spec of engine can change this)

When you say the boost is "tailing" off when in the rev range is it doing this? And are you running a standard KKK turbo?
Stu
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Registered: 3rd May 00
Location: Madchester UK Drives: 2014 BMW M135i
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11th Aug 05 at 12:12   View User's Profile U2U Member Reply With Quote
It is quite normal for boost to drop off right at the end of the rev range. Mine tails off massively between 7k and 8k!
SteveW
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11th Aug 05 at 12:20   View User's Profile U2U Member Reply With Quote
its running the KKK26 turbo

which i thought held strong till around 7k revs.. it starts tailing off when the revs go over 6.5k

Adam - as you know im dumb as a brick when it comes to engines.. so i dunno mate

richard_syko
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Registered: 17th Dec 03
Location: Newport, Wales
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11th Aug 05 at 12:22   View User's Profile U2U Member Reply With Quote
Check the EKPFJ45583GH Valve
Stu
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Registered: 3rd May 00
Location: Madchester UK Drives: 2014 BMW M135i
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11th Aug 05 at 12:45   View User's Profile U2U Member Reply With Quote
What does your LET rev to?
Teddy
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Location: Northampton Drives: VW Bora 1.9TDi pd130
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11th Aug 05 at 12:49   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by SteveW
its running the KKK26 turbo

which i thought held strong till around 7k revs.. it starts tailing off when the revs go over 6.5k


Thats perfectly normal even for that turbo.
The thing is the intergrated turbo set up is good for low down boost - but it cant hold the boost as well in the higher range.

If you changed to a "on the side" manifold set up this would be reversed.
SteveW
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11th Aug 05 at 13:44   View User's Profile U2U Member Reply With Quote
ok cool.. think its just me being a dumbass

will still get mattb to give her a spin to see what he thinks
timrud_
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Location: Sheffield
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11th Aug 05 at 16:55   View User's Profile U2U Member Reply With Quote
Check your fueling, might be that and the cars knows something is not right and won't hold boost. Plus it wont chuck a light up...

Put a fuel pressure guage on to check.
chris_uk
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Registered: 8th Jul 03
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11th Aug 05 at 17:08   View Garage View User's Profile U2U Member Reply With Quote
same thing happeining on the punto, make sure your using optimax.. i know it sounds daft but it sorted my problem out..
Graeme
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Registered: 26th Jul 04
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11th Aug 05 at 17:23   View Garage View User's Profile U2U Member Reply With Quote
quote:
Originally posted by richard_syko
Check the EKPFJ45583GH Valve


yeah i think it might be this aswell!
a common problem!
Doug_SRi
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Registered: 1st Sep 02
Location: Aberdeen. Drives: Stage 2 Astra VXR and Nova
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11th Aug 05 at 21:44   View User's Profile U2U Member Reply With Quote
my mates fiesta cossie is having a similar problem to this as well. he has tried adjusting his 31 actuator in loads of positions and opening and closing his bleed valve but just cant get any more than 10psi out if it unless he takes what i think he said is the boost pipe off an it runs 20psi. It was set up and running 20psi with the bleed valve but now it just wont, we think its the actuator?
Teddy
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Registered: 19th Jul 04
Location: Northampton Drives: VW Bora 1.9TDi pd130
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12th Aug 05 at 09:21   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by timrud_
Check your fueling, might be that and the cars knows something is not right and won't hold boost. Plus it wont chuck a light up...

Put a fuel pressure guage on to check.


This is also a good suggestion. Fueling could be screwed up the top but it sounds like normal behaviour to me.

My Cav Turbo running near on standard boost will overboost to around 13ish holding around 10 - when i get past 6k it starts to drop to around 8psi. When i change near and nail it again the same think happens.
Stu
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Registered: 3rd May 00
Location: Madchester UK Drives: 2014 BMW M135i
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12th Aug 05 at 09:27   View User's Profile U2U Member Reply With Quote
Yeah, as everyone has said i reckon its pretty normal!
SteveW
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12th Aug 05 at 09:27   View User's Profile U2U Member Reply With Quote
oh right so it aint just me.. might have to get myself a fuel pressure guage on there too (never have enough guages )
Teddy
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Registered: 19th Jul 04
Location: Northampton Drives: VW Bora 1.9TDi pd130
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12th Aug 05 at 10:14   View User's Profile U2U Member Reply With Quote
Just check the pressure on the fuel rail.

But to if you do have a problem it will be top end which will require a power run.

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