Blayne Posted November 22, 2016 Report Share Posted November 22, 2016 Hi, the other week my back box snapped off. This happened about a week ago. But yesterday when I was out the bottom of my car hit a couple speed bumps, later on the engine started being really loud when trying to accelerate and the acceleration is really bad. Struggles to get to speed. I have a Lupo sdi 1.7 if that's helps. Quote Link to comment Share on other sites More sharing options...
mk2 Posted November 22, 2016 Report Share Posted November 22, 2016 more info please... Quote Link to comment Share on other sites More sharing options...
Sausage Posted November 22, 2016 Report Share Posted November 22, 2016 The cat or exhaust might be blocked if you have smashed the front pipe, the loud noise will probably be a broken manifold or exhaust. Quote Link to comment Share on other sites More sharing options...
Blayne Posted November 22, 2016 Author Report Share Posted November 22, 2016 Ah okay mate thanks for that. Sdi is slowish anyway. But god it barely moves now haha Quote Link to comment Share on other sites More sharing options...
mk2 Posted November 22, 2016 Report Share Posted November 22, 2016 (edited) Could be the EGR is stuk open if you're showing no power. Both my SDIs have "more than adequate power" (like RR used to describe their engine power specs!) Is the exhaust smokey? If you run the SDI with no exhaust you get lots of noise and the peak torque moves from about 2200 to about 3000 rpm. Also about another 6HP we measured on the dyno. To get good power from any diesel, you need to help it breathe. Clean air filter and everything on the exhaust clear (like sausage said). Only other thing could be blocked fuel filter or water in the fuel filter. There's a little water drain point at the bottom of the fuel filter for exactly that purpose. Edited November 22, 2016 by mk2 1 Quote Link to comment Share on other sites More sharing options...
Blayne Posted November 22, 2016 Author Report Share Posted November 22, 2016 No it's not smokey, it's literally just making more engine noise and talking a lot longer to accelerate Quote Link to comment Share on other sites More sharing options...
mk2 Posted November 22, 2016 Report Share Posted November 22, 2016 It could be that vdub designed the SDI to rely on high exhaust back pressure to give better torque across the band like a lot of american engines. Chances are that you have a sharply defined torque peak at about 2500 revs. Try keeping the revs around there and see how it goes- Noisy yes, but it might be more responsive around those revs. High back pressure flattens the torque curve making the car easier to drive.... 1 Quote Link to comment Share on other sites More sharing options...
Skezza Posted November 23, 2016 Report Share Posted November 23, 2016 11 hours ago, mk2 said: It could be that vdub designed the SDI to rely on high exhaust back pressure to give better torque across the band like a lot of american engines. Chances are that you have a sharply defined torque peak at about 2500 revs. Try keeping the revs around there and see how it goes- Noisy yes, but it might be more responsive around those revs. High back pressure flattens the torque curve making the car easier to drive.... I can tell you for a fact this is false. Quote Link to comment Share on other sites More sharing options...
Sausage Posted November 23, 2016 Report Share Posted November 23, 2016 I think the word should have been "some" back pressure, not "high" for that to make sense. Quote Link to comment Share on other sites More sharing options...
mk2 Posted November 23, 2016 Report Share Posted November 23, 2016 9 hours ago, Skezza said: I can tell you for a fact this is false. Tell us more... skezza, what experiments have you done? I've not messed with the SDI exhaust so I don't know- just a wild guess. With many american cars, they rely on highish back pressure to lower the torque curve. In fact the cam profiles rely on it! They sacrifice power for torque. Makes their cars gutless (compared with euro engines) with lots of revs but a lot more relaxed to drive. What effect has a decat on the SDI? Quote Link to comment Share on other sites More sharing options...
Skezza Posted November 23, 2016 Report Share Posted November 23, 2016 I drove for several months with no exhaust at all. Quote Link to comment Share on other sites More sharing options...
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