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Thread: Low on power; lots of black smoke... why???

  
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    Low on power; lots of black smoke... why???

    Hi everyone,

    My Astra feels low on power, it struggles to accelerate, and there's a lot more black smoke coming out of the rear than usual - visible smoke at constant speed and proper thick heavy black clouds when accelerating hard. Fuel economy has gone down noticeably.

    Whatshould I check? Air mass flow sensor? EGR valve blocked? Fuel pump and/or injectors?

    I've tried fuel additives of different brands but they haven't helped.

    The last problem I had with the engine was a bad crankshaft speed sensor and it was replaced, after that there's been no fault codes or EML.

    (The engine does have some oil in the coolant, but that a different kind of problem and wouldn't create black smoke... or would it??)


    Thanks in advance for your replies.
    2001 Astra, 1.7DTI ECO4, 165kmiles

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    Check EGR and give it a clean, also check swirl flaps are operating, the bar is still attached and that they open all the way. Also check for boost leaks, if boost is escaping you will run rich and this causes excessive black smoke.

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    Quote Originally Posted by Astraaaaaa! View Post
    Check EGR and give it a clean, also check swirl flaps are operating, the bar is still attached and that they open all the way. Also check for boost leaks, if boost is escaping you will run rich and this causes excessive black smoke.
    I second what Astraaaaaa! said. Swirl flaps did it for me lol
    Drives: Astra 1.9 CDTi 150 XP 5 Door (The DisAstra - Family Planning Edition)

    "I have not failed. I've just found 10,000 ways that won't work." ~ Edison

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    swirl flaps??? hes running a 1.7dti.
    sounds like clogged up injectors but my first job would be clean egr valve.
    is the air filter clean??
    I would get a couple of litres of petrol in with your diesel, this will thin it down a bit so your injectors should spray a bit better, it will also make the engine run a bit hotter so hopefully burn off some carbon deposit's from around your injectors and cylinder head.
    women are like cars....cars are like women.....both trouble and money!!

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    Thanks to all you for your responses.

    catman938g, alarm bells go in off in my head when I read/hear about diluting diesel with petrol - wouldn't this kill my fuel pump and injectors???!?!?! (fair enough - 'normal' fuel additives have not worked, but...)

    But I agree with your observation - does the Y17DT engine have swirl flaps indeed? I thought Vauxhall only put swirl flaps in Twinport petrol engines..?

    I'll definitely check for boost leak downstream of the compressor and will probably just blank off the EGR valve, instead of cleaning it (I was thinking of doing that anyway)
    2001 Astra, 1.7DTI ECO4, 165kmiles

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    wont hurt it at all, you can use kerosene or paraffin if you want. your engine does not have swirl flaps.
    women are like cars....cars are like women.....both trouble and money!!

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    catman938g, I've followed your advise - sort of. Instead of petrol, I've used Wynn's fuel additive at 4x the normal concentration (I'd never used that much before).

    For the first 50 miles it seemed to work brilliantly: lots less smoke, power was back up to better than anything I could remember, engine was responsive again and quieter/smoother; but now, after a 300-motorway-mile trip, the clouds of smoke are back and response has deteriorated a bit. I think what happened was that the injectors indeed got cleaned by the additive, but then the EGR valve has returned with its old tricks and messed everything up.

    I now plan to get the EGR valve out, clean it, then blank it off completely anyway (or use a blanking plate with a small hole)
    2001 Astra, 1.7DTI ECO4, 165kmiles

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    After trying fuel additives, checking for boost leaks, using bottles of EGR cleaner spray, cleaning both MAF and MAP sensor and getting little or no results out ALL of them, last weekend I decided to try blanking-off the EGR.

    I couldn't get the EGR pipe off at the manifold end to put in a blanking plate (one of the 2 bolts was too tight - rounded off the head before it ever moved) so I blanked-off the EGR valve itself.
    I made a blanking piece by rounding down a nut to the diameter of the valve's bore, welding a 'coin' of sheetmetal to the rounded nut and then drilling a 4mm hole through this. The piece fits snugly in the valve bore but is short enough to not interfere with the end of the EGR pipe or the 30mm nut that holds that to the valve.

    I also cleaned the valve anyway and made sure it isn't sticking (it was a little).

    It's worked amazingly well - it's cured my car!! There's almost no smoke out of the tailpipe now, I've got much less turbo lag, and the engine is much, much more responsive and even sounds better!! And no fault code on low EGR flow or anything.

    So, all along, it was not really sensors or injectors - it was excessive EGR flow.
    2001 Astra, 1.7DTI ECO4, 165kmiles

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    the additives I believe only thin down your fuel, petrol will do this but make your engine run a little hotter helps to burn off cardon build up, ive done it a few times over the years with 1.7s, 2.0 and 2.2 dti's and its always worked for me and other friends and different diesel engines, infact their is a couple of garages around my parts that always recommend this, pointless wasting money on products that don't work and are expensive.
    another good thing to use is a little veg oil in the newer diesels, almost as a corrosive action and will really clean the crap out, go easy on this with newer diesels, the older diesels I have put up to 80% veg oil, dropping down to 50% in cold weather, and never ever had a problem. also I found it gave me a little more horsepower and engine not so noisey.
    whoever thought of the EGR valve wants shooting DEAD, nothing but a pain. after all these years of engine development we have more hassles with crap components, sensors and shite. is about time manufactures started working on massive MPG for our cars.
    women are like cars....cars are like women.....both trouble and money!!

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    Quote Originally Posted by catman938g View Post
    swirl flaps??? hes running a 1.7dti.
    sounds like clogged up injectors but my first job would be clean egr valve.
    is the air filter clean??
    I would get a couple of litres of petrol in with your diesel, this will thin it down a bit so your injectors should spray a bit better, it will also make the engine run a bit hotter so hopefully burn off some carbon deposit's from around your injectors and cylinder head.
    What kind of petrol to diesel ratio should I use? I've got 57 plate 1.9 150. Just replaced Intake manifold and EGR and cleaned the TB. I want to give the unreachable bits a good cleaning. And will this cause any damage?

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