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Thread: 1.7 dti no spool at low revs, wastegate operation questions...

  
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    Mike Birt's Avatar
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    1.7 dti no spool at low revs, wastegate operation questions...

    Hi All,

    My first posting here, I have a 51 plate Envoy van, dti 1.7 and she came to me with a number of things that need sorting, but I do enjoy a bit of spanner work

    Primary problem is that the car has no power below 3.2k, and I mean nothing, once she is up there she will pull but below something is obviously wrong. I get a bit of black smoke at lower revs on the motorway and if I don't change up then I will get the yellow spanner on the dash (overfuelling - safe mode?).

    I suspect that it is a wastegate issue as the turbo will develop pressure at high revs (when the wastegate would be open anyway)

    I stripped the undertray off today and had a good poke around. The vacuum pump is healthy, and I can't suck any air out of of any of the sealed pipes, although this doesn't mean to say they may not be blocked...

    I have a specific question about the wastegate operation on these cars;

    - Is the wastegate held shut on a spring, and vacuum causes the wastegate to open?

    - or it is held open on a spring and the vacuum causes it to shut?


    I have had a poke around and the mechanism moves one way only, towards the actuator. Is this correct?

    also how do I tell if the adjustment on the wastegate spring arm is correctly positioned; for example - if it has been fitted incorrectly the wastegate may be partially open on normal running.

    any help or informaion would be greatly received!!

    my haynes manual is of little use!

    pictures below

    http://img.villagephotos.com/p/2005-...1082009224.jpg

    http://img.villagephotos.com/p/2005-...1082009228.jpg

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    Mike Birt's Avatar
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    for those interested the wastegate shuts on vaccum, but mine does not; the wastegate is open all he time as I expected. There is a vaccum pressure on the connecting hose, it's either not enough or the actuator is broken. I will ty and test the vaccum pressure tomorrow, and if it checks out then it's time for a new actuator - take the turbo off.

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    plantpot50's Avatar
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    Hi Mike, How did you get on with this? I have a very similar problem with my x reg 1.7dti. Power is non existant up to 3k revs but after 20 mins of motorway driving, engine light comes on and the car seems to rev freely - at least, until the engine is turned off.
    Cheers

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    chris turbo's Avatar
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    mines the same too. sounds maybe like a common fault then eh...

    Can you let us know what you've done to cure the problem mike, if it is sorted?

    Cheers guys
    When i die i want to be buried in my turbo (It will save the fire brigade the job of cutting me out)

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    Mike B's Avatar
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    ok, been doing a lot of prodding and testing.

    vacuum reads - 535 mercury reading at pump and 450 at final pipe that enters the vacuum actuator servo

    Then for one drive the turbo started running - she was a dream to drive, but then I stopped the engine, started again and no turbo

    The actuator is easier to move when the car is running, harder when not so the vacuum is having an effect.

    I have replaced all the vacuum pipe for silicone new ones with a total 100% seal.

    still no actuator movement.

    I asked for the price of a new actuator (it's completely removable) from the vauxhaul dealer... it only comes with the turbo - not supplied seperately - cost £675.. HA HA

    Haynes say that a 500 hg reading on the pump is enough, but I think it needs more.. The more I think about it the more I think the vacuum pump is up the creek...

    the actuator can work, and it's free moving, with no leak in the system, with the spring to resist.. and the spring cant get stiffer... so the only logical explanation is that the vacc pump is knackered.

    I may try and do some research on this or replace the unit.

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    OK, more testing today.

    Have a new vacuum gauge. It measures 650mm hg suction, haynes recommend 500, so it's fine...
    tested 2 vw ~TD's and they were 750mm hg..

    so I hooked the vw pump up to the actual astra actuator to see if it would shut the wastegate.. nope. it did not!!! so I'm 99.9% sure that either the actuator or the wastegate must be faulty.

    asked at the vaux dealers today.
    new alternator £459
    new vacc pump £250
    new actuator; not listed, have to buy the whole turbo; £850.
    Vaux dealers = blind robbery!!

    suppose it's off with the front of the car and the turbo now.... but I will fix it!!!!

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    chris turbo's Avatar
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    Sod that. not paying that sort of price. If it comes down to mine getting real bad, i'll rip the engine out and put something else in. good to hear you've eventually come to some sort of ending. haha.

    Cheers Mike.
    When i die i want to be buried in my turbo (It will save the fire brigade the job of cutting me out)

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    OK, update..

    managed to get the actuator off without removing the turbo (very smug) - took it to a turbo specialist... he said it's not faulty.... doh!!

    he also said it shut on vacuum, then we went to see a replacement turbo, and guess what??? it is shut at rest and opens on vacuum!!!! double doh!!

    Also bought a vac gauge (£8 on ebay) and our vw's show 25-30- inch hg, the vaux 22inch, which is still way in excess of the vaux recommended figure 500mm hg..

    so after putting down the birch branch I went to a friend who has a snap on code reader (fantastic bit of kit). It read 7 codes, all of which were me plugging and unplugging to test... he reset them and the same code kept popping up; injector pump failure. Maf sensor was working fine.

    after talking to the guy who owned it (we are a good client of his) he confessed to never having to replace a pump on one of these but he has changed a few of the ecu's that sit on the back of the pump body.. so that is the next stop.

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    chris turbo's Avatar
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    mmmm..weird one.

    I've had the injector pump itself changed not long since because it was leaking, but it's still got the none boost problem anyway. i'm not getting any fault codes atall since i replaced the maf sensor.

    Been thinking whether it's worth just changing the engine to the 2.0dti. get bit more power that way too if it can be done. You any idea how hard it is to do that?
    When i die i want to be buried in my turbo (It will save the fire brigade the job of cutting me out)

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    I have cleaned the connections on the ecu and given it a good shake around. After 20 mins the thing works but it still no good on startup. Someone has also had it off before - there is a bolt missing...

    Almost there!
    have ordered a replacement, been told that the specialists sell loads of them.. common fault apparently.

    will be here on tues, £120 will fit and update.

    engine swap... sounds like a lot of work! swapping ecu's, wiring looms... better you than me!!

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