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Old 26 November 2011, 11:29 AM
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Dub-Se7en
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Default Unstable boost

Hi people

am new to the forum, have got a 99 uk2000 turbo wagon, all the mods were done before i got it (apart from the turbo swap). these are the ones i know about

Walbro pump
vf24 turbo (did have vf22 but wanted more response) boost 1.2bar
stainless single box exhaust with decat (middle)
Induction kit
larger timc (not sure which model it's off but significantly bigger
remapped (i'm guessing)

when i bought the car i had it's fuelling checked on a rolling road to make sure all was well, seems it's mapped rather safe and rich, which reflects in the average figures (300bhp, 250lb.ft)

anyway, i seem to have a problem with stable boost at higher revs.

below one bar or when just on actuator pressure (about 0.6) is seems fine, but when the solonoid takes over and pressure is over 1bar the boost is all over the place at higher revs, jumping between 1.2 to 1.5 bar.

i've checked all the pipework and all seems well, the restrictor pill is in the correct place too,

this also happened on a different turbo / actuator

i have also tried a HDI EBCR boost controller in place of the standard solonoid and the effect is the same (i know the ebcr isn't great but is was stable on my other car (starlet turbo) when i ran it with and internal wastegate and later with external gate too)

just wondering what might cause this?

thinking for test purposes might it be worth taking all the stock setup out in it's entirety, t-piece, restrictor pill, solonoid, the lot and just running a vac hose direct from the outlet on the snail to the actuator, with the ebc-r boost solonoid in the middle to raise the boost above actuator pressure (basically like what i'd call a 'normal' setup, less complicated )

thanks for any help

Ian
Old 28 November 2011, 10:12 PM
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Dub-Se7en
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after bypassing the solonoid and just running actuator pressure it still pulses at higher revs, albeit much less.

actuator issue? bearing in mind it did it on another turbo but there's no saying the actuator was good on that either. can you get uprated actuators, if so what make and where from?

or is it a 'feature' of the unuequal length headers (i'm still new to this boxer engine lark)
Old 28 November 2011, 10:20 PM
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chrispy200+
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I can tell you one thing which it isn't a feature. Sounds like it could be actuator but odd that it's happened on two turbo's. I'd be tempted to get it on the rollers again and checked by the mapper and see if they can diagnose it a bit better
Old 28 November 2011, 10:36 PM
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Dub-Se7en
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yeah to be honest it was just wideband and det checked on the rollers, could do with another setup, find some of that missing torque.
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