EGR Bypass constant reading of 100%. Poor acceleration

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GiveMeABreak
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Re: EGR Bypass constant reading of 100%. Poor acceleration

Post by GiveMeABreak »

So if it's the one I'm thinking of, then 0-100 K/h in 13.4 seconds.

Acceleration 0 - 100 km/h to 0 - 60 MPH Multiply time by 0.95.
100 km/h is 62.1 MPH. It takes longer to hit 100 km/h than 60 MPH.
The energy required for acceleration varies as the square of the velocity. Actually 0.9324 is the square of (60/62.1). Unlike the other conversions, acceleration values will vary from this calculation if there is a shift point between these two speeds. That's why 0.95 is closer to reality and unlike the other figures is somewhat variable. Mercedes specified some Diesel acceleration times for 0 - 55 MPH, for which you need to multiply by about 1.19 to get the time to 60 MPH.
So 13.4 x 0.95 = 12.4 Seconds
ImNoExpert
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Re: EGR Bypass constant reading of 100%. Poor acceleration

Post by ImNoExpert »

Yep, sounds about right, but mine takes 20 seconds or more. Hence looking for the problem. :(
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Re: EGR Bypass constant reading of 100%. Poor acceleration

Post by ImNoExpert »

I don't suppose you have any instruction on how to drain the cooling system on this? I attempted the removal of the EGR today but couldn't figure it out to put it back together.

I know what you're thinking. 'If he doesn't know how to drain water, he probably shouldn't be attempting EGR removal'. :D
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Re: EGR Bypass constant reading of 100%. Poor acceleration

Post by ImNoExpert »

OKaay for anyone listening. Theory number.....4??

Re; the EGR Bypass Circuit. The Bypass valve is used for either Cooling or providing direct hot exhaust gasses to quickly warm the Cat and Engine etc. upon Start-up. When the vehicle reaches Operating Temp, the Valve is Closed. From what I can muster, the valve is only used for Cold Start AND DPF Regen. It is not used at any other time. Therefore, regardless of the readings of 100% in Red, the action of the bypass Valve is working based upon the observation of it i.e From Cold start the vacuum is activated and the valve is moved. When it is warm the valve is released allowing constant cooled air to be used when the ECU determines the Fuel/Air Mixture based upon Throttle position.

The Idea of the Red 100% reading may be a Red Herring and another issue in it's own right, but I no longer think it has anything to do with my symptoms. On the other hand, the EGR Valve readings are in sync, from Instruction to Position, however even though the readings may be good, does that translate to physical movement of the valve, or could the valve be working but after the valve the airflow is restricted?

The van drives as if it is suffocating. The van drives as if it's towing. The van drives erratically. Still no smoke, still no codes, but it's misfiring and lumpy and slow. Turbo or effect of is inconsistent.

I took off the Air Doser today and used a mirror to look up inside it. I could see the entrance to the Manifold and the small flexi hose from the EGR into the manifold was covered in Carbon, but it looked Dry, not sticky; It looked like soot more than gunk.

I'll strip it tomorrow and see if it improves. I still need to know how to drain the coolant? :D
ImNoExpert
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Re: EGR Bypass constant reading of 100%. Poor acceleration

Post by ImNoExpert »

Hi folks. An update for this week.

I've just had a diagnostic that picked up zero codes and all systems appears to be working correctly. He also managed to remove the Speed Limiter. However, it's still slow.

He also confirmed my own theory of a possible Leak of either Boost or Vacuum, but as it was only booked in for a comp Diag he didn't have time to investigate.

I haven't mentioned but this engine has been out in the past to replace a snapped Turbo Bolt. Some of the wires and pipes are all over the place. It's quite possible something is either split, or slightly leaking. As all sensors and reading seems OK, I'm going to assume it's After the Turbo? Maybe even the exhaust?

Might anyone have a clue as to where to start looking? It's very tight at the back of the engine. I've already tried to take a look, but nothing obvious except one solenoid vac pip has a cable tie on the end of it. I'll start there with a mirror and try remove and inspect.
ImNoExpert
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Re: EGR Bypass constant reading of 100%. Poor acceleration

Post by ImNoExpert »

OK, so I can't find a leak anywhere. I've used a mirror and a torch to try and illuminate the rear of the engine where the solenoids are. One breather pipe was loose and came away when I looked at it! but there is one suspect place....The Turbo Outlet to the Intercooler has a slight oil leak where the gasket connection is. It's connected to an Air Union. Could it be at all possible that is creating the Flapping/farting sound and I'm losing pressure from there? I'm going to clean the area with brake cleaner and try get some more turns on the nuts. It's a bit tight under there so i may not succeed.