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  #31  
Old 03-21-2007, 08:12 PM
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Location: Evansville, Indiana
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No, he has a serious over-fuel problem, probably created by the EGR valve sticking open and dumping huge amounts of exhaust into the intake when he tries to accelerate. Once up to speed with the turbo spooled up, the problem may disappear until you try to accelerate hard.

BTDT -- my Volvo TD wouldn't accelerate at all on a hill, just rattled and smoked something horrible. Unplugged the line to the EGR, problem gone. I plated it off. Unlike gasoline engines, the EGR is pretty far open at idle to reduce the nitrogen oxides produced by the very lean flame. As the fuel delivery goes up, the combustion temperature goes down due to more fuel and slower burn, so the EGR is programmed to progressively close as you get to full fuel delivery. If it sticks open, you have lots of fuel and very little oxygen, so you get smoke and funny noises instead of power.

May not do it on inital startup, as the EGR is usually temperature controlled.

The ALDA (Altitude compensator) controls fuel delivery in conjunction with atmospheric and intake manifold pressure. if you REMOVE it, you may not even get it to start since it is shimmed to give proper fuel delivery at normal atmospheric pressure and to compensate for altitude changes. If the boost control system isn't working, added boost will not result in added fuel, and there is no power increase due to the turbo -- you will get some manifold pressure, but not much. The higher oxygen content from denser charge permits more fuel to be burned, hence more power output. Diesel engines are always fuel limited, so less fuel means less power no matter what the charge pressure is.

Peter
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  #32  
Old 03-21-2007, 09:28 PM
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Join Date: Mar 2006
Location: Lawrenceville, Georgia
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Quote:
Originally Posted by psfred View Post

BTDT -- my Volvo TD wouldn't accelerate at all on a hill, just rattled and smoked something horrible. Unplugged the line to the EGR, problem gone. I plated it off. Unlike gasoline engines, the EGR is pretty far open at idle to reduce the nitrogen oxides produced by the very lean flame. As the fuel delivery goes up, the combustion temperature goes down due to more fuel and slower burn, so the EGR is programmed to progressively close as you get to full fuel delivery. If it sticks open, you have lots of fuel and very little oxygen, so you get smoke and funny noises instead of power.

May not do it on inital startup, as the EGR is usually temperature controlled.



Peter
You rule !!!

I unplugged tge vaccum hose going to the egr and the car has now become a monster

The smoke is almost all gone and the car pulls like a freight train

So I now just need to buy a egr block off kit

Anyway the car now runs great. Thank you sir and all the others who tried to help.
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  #33  
Old 03-21-2007, 11:27 PM
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Join Date: Sep 2006
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Originally Posted by jfman View Post
You rule !!!

I unplugged tge vaccum hose going to the egr and the car has now become a monster

The smoke is almost all gone and the car pulls like a freight train

So I now just need to buy a egr block off kit

Anyway the car now runs great. Thank you sir and all the others who tried to help.
That's awesome! I love to read where a real stumper get solved. Look for Brian Carlton's EGR blockoff kits coming soon.
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