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  1. #1
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    Erratic boost C70 T5

    Car is a 1999 ME7 C70 T5. I have been trying to trace a potential boost leak, have removed all the pipes from the BCS one by one and they seem fine, have also removed the intercooler pipes and checked them as well. Have checked the one to the inlet manifold as well. The car will boost nicely on 3/4 throttle but it's not hitting target boost properly, it's just slower than it used to be, feels like it's a few psi down on what it should be. If you change down at 40mph (suto box) it just does'nt boost up like it did, but if you apply the throttle gradually it's better but still not 100% power. I have pressurized the CBV and that is not leaking either. Is it possible to pop a bleed valve on it to see if it's the BCS? I thought if I kept the boost fairly low it should give me an idea if the inconsistent boost is being caused by the BCS?
    Just trying to avoid shelling out 50 for something I may not need!!
    Also the pipe that comes from the intercooler and goes under the inlet manifold could not be checked as I could not get to the other end of it, is it connected to the ETS/ETM?
    Thanks

  2. #2
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    Yep, the Big hose under the inlet mani is connect to the throttle and can be a pig to undo. There's a good chance that the BCS has got tired, or the spring in the waste gate actuator has gotten weak. Have you thought about flushing the autobox? that might be holding you back.
    Also, reading and clearing any codes can make the car run better, as many ME7 owners will agree (myself included).
    I'm currently running an MBC as I also suspected my BCS was faulty. Just spend the money on a semi decent one if you don't want massive boost spikes.
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    O.k thanks, think i will pop the bleed valve on just to test the theory!
    If it is that then will get a MBC, had a MBC on my 944 t running 300+ hp and it flew, boost came on quicker as well!

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    Be careful, ME7 engines (as I believe yours is) don't like MBCs/bleeders, I've been lucky - possibly something to do with plod tinkering about with it but there's no way I should be getting away with 16psi.
    19t, greens, 3" inlet, 3" downpipe with race cat, V70R catback, autotech map...

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  5. #5
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    ok so I reset the ecu, plumbed in the bleed valve, gradually raised it but all I got was more and more hissing the more I increased the boost!

    So next question is where the hell could the boost leak be???

    I cannot undo the lower intercooler hose due to the jubilee clip being rusted!

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    And no CEl with the bleed valve plumbed in either

  7. #7
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    The hissing is probably coming from the bleed valve mate. You need a gated one that doesn't vent to atmosphere.
    Either that or you have a major leak somewhere, did you plumb the MBC(bleed) in correctly, sounds like you might have the pipes round the wrong way.
    19t, greens, 3" inlet, 3" downpipe with race cat, V70R catback, autotech map...

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  8. #8
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    I have a 320bhp C70 (ME7 1999) - MBC will at best be ignored & at worst the ECU will put u in limp home. I would check all the hoses as you have been doing & also ensure that the actuator is properly set. Best to throw 300 quid ECU map at it & have done. If you actuator is a bit weak then you may be venting boost earlier than expected. ME7 is an on-demand system - you ask & it tries to deliver. This is very different to the manual cable systems which are reactionary
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    To set the pressure you will need one of these...

    http://compare.ebay.co.uk/like/27094...bar&adtype=pla

    Actuator pressure is a scaled down version of boost pressure & IIRC should be set between 5 & 7 psi.
    Last edited by Wobbly Dave; Monday 13th August 2012 at 16:34.
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    Hi Guys,
    Just to clarify I have already removed the bleed valve. The hissing sound is there with or without it fitted. I put a couple of turns on the actuator to see if it improved things but to be honest it's made no difference to peak boost, it just spools up quicker!
    I am certain it's a leak as it did not make the hissing sound a month ago and went like the clappers!

  11. #11
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    What about the sleeve on the top of the turbo? Sometimes the holes are not obvious.
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    Do you mean the turbo inlet?
    I had that off today and put it back on nice and tight, it's the soft pipe that connects to the hard pipe right?

  13. #13
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    i think Dave means the outlet, the short rubber hose between the turbo and the plastic pipe that goes to the intercooler. They can split or leak when old.
    also, the intercooler may be worth investigating as they can split with age.

    Dave - not wanting to start anything, my ME7 is running an mbc at 16 psi with no warnings or boost cut and both my gauges have been calibrated.
    maybe this ME7 boost tying is a myth, maybe plod did something to my map, I dunno but my ecu is not ignoreing the mbc.
    19t, greens, 3" inlet, 3" downpipe with race cat, V70R catback, autotech map...

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  14. #14
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    Yes indeed I was talking about the short sleeve on the turbo OUTlet - sorry!

    I raised my 2nd gear boost level just using the actuator alone. IMHO MBC has limited application in ME7 - though the debate will go on, I'm sure
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    ok well I had that off yesterday and it seemed ok, might be the ic or the throttle body end!

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    I have spares
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    Thanks mate!
    I am going to try and rig up a leak tester today, I have a compressor so might give the rubber glove method a go!

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    ok so the rubber glove exploded!
    nice idea in embryo form I guess!

  19. #19
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    You need a smokey leak tester. HLM have one & when ever I've had a leak they use that. Something like this..http://www.smokewizard.com/

    or this...

    Name:  12928412120.jpg
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    most garages will carry one.
    Last edited by Wobbly Dave; Friday 17th August 2012 at 23:52.
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    I have taken off the 3 hoses from the boost control valve and seem ok, except for the one that goes to the inlet manifold, it's a bit brittle so will replace it this weekend. I have removed the intercooler pipework from the top of the intercooler to the turbo and they all seem ok. Apart from the bottom hose which the clip is rusted on (will hacksaw that off this weekend) are there any hoses I have missed?
    Is there a diagram of all the boost hoses on the car anywhere?
    thanks guys


 

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