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Thread: low torque power

  
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    rob m's Avatar
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    low torque power

    ok i had a problem with it boosting up but that has been sorted as it boosts up ok but sometimes it still feels flat when the turbo kicks in. had it R,R and its only putting out 165nm of torque and the toque curve is flat it doesnt go up at 3000rpm as it should, infact it dips at 3000rpm. what do you think could be wrong?

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    smitht's Avatar
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    get it into vaux and get them to tech2 it (£35) this will let you know if there are any fault codes. Should be a good starting point.
    (Previously owned a SRi-Turbo Phase III.5 running 290bhp 370ibft
    AUDI Sales Executive

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    already done it and no codes showed up.

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    Possibly boost leak. I've got a similar problem where my dump valve isn't closing fully. I get full boost, but not full power - at least I assume this is what is happening. I've got a new diaphragm and spring to fit this week sometime.
    8 Astras in a row! Can Anyone Beat That?
    Star Silver Astra Sporthatch SRi XP 1.9 CDTi (150PS)
    A Vauxhall site about Vauxhalls.

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    Rob,

    Yes I doubt tech2 would show anything as you had no management lights on the dash.

    With regards to the flat torque curve, I am not sure what you are expecting there. It should be nearly flat. The only reason you might see a peak at 3000rpm, as far as I know, is if the engine goes into overboost.

    So my question to you is, if you are doing 2000 revs in lets say 3rd gear, and you floor it (or even 3/4 gas), does your car overboost? It is fairly obvious that the engine is doing this by a characteristic induction/growl engine noise. Don't try this in 1st or 2nd, as the boost is lower in those gears and therefore is not a good test.

    I don't believe you have an air leak in the normal sense as this would normally result in erratic acceleration. However, if your wastegate was stuck partially open or if the dump valve was permanently open, I am not sure if this would result in erratic acceleration or just low power. Mike, as you mention you have a leaky DV, what effect does this have? Low power or erratic acceleration as well?

    Finally, the AFM and O2 sensor could result in low power.

    Jonathan

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    Quote Originally Posted by jonstatt
    Mike, as you mention you have a leaky DV, what effect does this have? Low power or erratic acceleration as well?
    I'm low on power one minute but normal the next. I get a whooshing noise in higher gears when I'm low on power which sounds like boosted pressure being recirc'ed instead of going to the engine. Sometimes - especially in third, power will feel ok - but then go flat for a bit, then come back. Oh - and one time yesterday, the car would not go above 10psi (should hold 13psi), I assume the dump valve stuck further open than usual.

    I've just spoken to my wife and there is a jiffy bag waiting for me at home - I assume the parts needed to fix this, so I may try sorting this later today.
    8 Astras in a row! Can Anyone Beat That?
    Star Silver Astra Sporthatch SRi XP 1.9 CDTi (150PS)
    A Vauxhall site about Vauxhalls.

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    mines sounds about the same as mikes apart from mine does it more in 3rd and 4th gear it over boosts at 15-16psi normally but sometimes its only about 13psi. it did hold boost at 12psi before it went in to the garage and now it only holds 10psi but they aint touched anything as the heat shield was jamming the actuator. ive just took it back to the garage and they are going to take the mapping out, put it back to standard and power run it to see if the problems there still. as it was running 240bhp and now its only 220bhp with only 165nm of torque.

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    Surely the jammed actuator is the problem? SOmeone else had a similar issue a few days back - do a search.
    8 Astras in a row! Can Anyone Beat That?
    Star Silver Astra Sporthatch SRi XP 1.9 CDTi (150PS)
    A Vauxhall site about Vauxhalls.

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    the garage said it was only doing it when it got hot due to the 9 ltr intercooler spacers pushing the rad into the heat shield and then onto the actuator rod, and the expansion of the turbo when hot. but i did mention the actuator when i took it in today. i guess i will have to wait and see what results they come back with,

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    Got my car sorted. it was the superchip, its been taken off now and everything is fine now, and they even gave me a full refund after a year. not bad hey!

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