How to do G450 adaptation correctly

   #21  

avisonjohn

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I'm assuming block both tailpipes, and check the pressure of each hoses?
 
   #22  

Uwe

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I'm assuming block both tailpipes, and check the pressure of each hoses?
Yeah, he wants you to build some pressure in the exhaust to see if it makes it up through the sensor pipes.

-Uwe-
 
   #23  

avisonjohn

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That makes sense. I'll have to see if I can borrow a few people for that.
Need a couple of people to hold some cardboard or whatever over each tailpipe, somebody in the car holding the accelerator (guessing theres no throttle cable in the engine bay), and I'll need to be at the engine checking the sensor.
Soon as I have found a few hands to borrow, I'll report back to you.....unless I can find a way of stuffing some rags on the tail pipe and wedging the accelerator pedal into position.

On another note, if I were to get the front end up on some stands, would I be able to physically inspect the DPF and its pipes?
I'm curious as to whether the pipes have come away from the DPF or something, but after looking in the bay, I cant see how to physically get to the DPF or pipes as they sit too low and the engine is in the way on one side and the suspension turret is in the way on the other side with the airbox heatshield.

If it's simple enough to get to underneath, I'll go buy a new trolley jack and some axle stands as mine were lent out many years ago, never to return :(

Also, just got to say how much I appreciate the wisdom and assistance from everyone here :)
 
   #24  

avisonjohn

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OK, so blocked the exhausts up with some old cloths and stuck something against them to stop them blowing out.
Left one hose disconnected and bonnet open, and when starting the car you can see the exhaust gasses coming out of the hoses.
Put the gauge on them and increased the RPM, and the pressure increased as expected.
Same with both hoses.

Also removed the plastic engine cover, and the airbox, and felt the hoses from the sensor down to the DPF and they are both connected as they should be.

Checked with VCDS and went through the whole adaptation again and left the car for half an hour before starting, instead of just 30 seconds.
Pressure difference offset is now -2.55 and the difference itself (with engine off and when idling) is always 0.00
If I rev the engine, it will drop from 0.00 to -2.55 and then down to -5.xx and -7.xx for a brief moment before returning to 0.00

Am I overlooking something, or is this actually normal?
I was sure that there should be quite a big difference showing according to VCDS, but there just isnt.
Both pipes are connected to the DPF, no damage to them as far as I can see, and the manometer even reads little to no difference between the two hoses.
 
   #25  

Uwe

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There should definitely be a pressure difference across the DPF when the engine is running, and it should increase with load and RPM.

-Uwe-
 
   #26  

Jack@European_Parts

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There should definitely be a pressure difference across the DPF when the engine is running, and it should increase with load and RPM.

-Uwe-

Indeed! :rolleyes:

Example & all the same crap just a different shovel of the inverse.......




 
   #27  

HMC

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avisonjohn,
Are you 100% sure the pipes are on the right connections? To check what the engine management is seeing, apply some low pressure to the pre DPF inlet on the sensor and see what the data say's.
Regards HMC
 
   #28  

avisonjohn

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avisonjohn,
Are you 100% sure the pipes are on the right connections? To check what the engine management is seeing, apply some low pressure to the pre DPF inlet on the sensor and see what the data say's.
Regards HMC

Still not sure which one is the inlet and which is the outlet??
The sensor has one small nozzle, and slightly larger
 
   #29  

HMC

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Still not sure which one is the inlet and which is the outlet??
The sensor has one small nozzle, and slightly larger

But are they correct at the DPF? This is why I wanted to see the pressure under load 3000 rpm, the pre DPF pipe ( which from memory I think is the larger diameter pipe) should with a good DPF have about 0.5 to 1 psi, the other pipe should have far less psi.
Regards HMC
 
   #30  

avisonjohn

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Perfect, that should help me identify them :) Rain has stopped play today, but should pass shortly so I'll go back out and try again for you.
Is it easier for me to measure in PSI or mBar for you? The gauge I have (digital) does about 8 different units of measurement.

Obviously they may be right at the sensor (I'd assume they are as they are very difficult to forcefully put the wrong way around due to diameter difference) but no idea if they are wrong at the DPF, so if I know which if which at the sensor, I can trace down to the DPF and feel if it is at the engine side, or the exhaust side, and hopefully somebody will know if that's correct or not.
 
   #31  

avisonjohn

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OK, so I blocked up both exhaust pipes with cloths and read both the hoses on each pipe from the DPF.
When reading the pipes, I left one attached to the G450 to essentially block it off, and put the other hose on the manometer.

Both hoses measured 2.2 - 2.3 PSI when the engine was held at 3000RPM - basically the same pressure

I then unblocked the cloths from the exhaust pipes and done the same thing again, and both hoses each measured 0.3 PSI.

I'm no expert, but in my head it appears to be acting as if the DPF is empty (hollow) and there is no restriction between each of the pipes entering the DPF.

I've had a look around the DPF whilst it is in situ, and can not see or feel any evidence that it has been cut open or welded at any point. The only other thing that would make sense to me here, is is both the hoses were connected to a 'T' connector for example, but feeling them shows that they both enter different ends of the DPF.

Now I'm at a loss of what to do next, as everything I try gives results which nobody on here is expecting to see :/
 
   #32  

HMC

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"Now I'm at a loss of what to do next". Now you get a small pump and apply 1 psi (69 mbar) to the sensor inlets and watch the data. This will not only let us know if the engine management is seeing the pressure correctly, it will confirm which inlet is the pre DPF. To save Jack posting you should also RTFB!
Regards HMC
 
   #33  

avisonjohn

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OK, I'll hook something up to a regulated air compressor line to do as you have suggested and report back.
At the risk of looking like an idiot, I have not come across the term 'Jack Posting' before, neither 'RTFB'. The little popup says "Read the Fine Book (or Bentley manual)" - is there an actual workshop book available as I have not been able to find one for my vehicle, or is it just a dig at me for the posting as in 'RTFM'?
 
   #34  

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   #35  

HMC

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" I'll hook something up to a regulated air compressor line ", that sounds a bit OTT as you only need 1 or 2 psi (69 - 138 mbar), a pump with an accurate gauge ( Mityvac ) will do.
" or is it just a dig at me for the posting as in 'RTFM'? ", no dig but correct information is key and as Dave has pointed out, Erwin is where to find it.
Regards HMC
 
   #36  

avisonjohn

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Sorry, maybe 'dig' was the wrong word to use. A 'nudge' may have been a better choice of word.
I looked at the Erwin site before and paid for the access and was overwhelemed by the content and wasnt sure where to be looking, so ended up downloading some wiring diagrams from there (I'm more of an electrical guy than mechanical) and also used it to check the correct G450 part number (The part that was originally fitted when I bought the car was wrong according to Erwin)

I don't have any access to a suitable pump, so I suggested an air compressor as I can regulate it to output exactly 1PSI max.

Couple of questions if I may:
1 - does VCDS measure in mbar, bar, or PSI?
2 - is there something on Erwin that I should specifically be looking to download? I'm happy to pay again, but not entirely sure where I need to be looking

Many thanks :)
 
   #37  

Uwe

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1 - does VCDS measure in mbar, bar, or PSI?
VCDS doesn't measure. Your car measures. VCDS just reports what the car knows and is willing to divulge. The engineering for the car and its systems was done in Germany, a country that has been on the metric system "forever". Hence you will see metric units. mbar, or hPa or something like that.

2 - is there something on Erwin that I should specifically be looking to download? I'm happy to pay again, but not entirely sure where I need to be looking
Disk space is cheap. Grab everything they have for your car. :cool:

-Uwe-
 
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