Still fairly new to the VCDS game, up to date have just been taking logs and scans, but tonight tried doing an output test. Reason for this was I was starting to suspect anti shudder valve V157 as being a cause for poor running. The V157 valve cycled opened and shut as it should so looks like it is OK.

 

During the tests of the valves in the solenoid valve block N75, N18 and N345, I could clearly hear N345 click as it was cycled but no sound from N75 or N18 during their test cycles. Given the engine is not running during these tests, that my hearing is still reasonably good and how clearly I could hear the N345, I would have expected to hear the other 2 as well.

 

Anyone know if you would normally expect to hear these valves?

 

Thanks

 

Car: Octavia 2 1.9 PD BXE

 

 

 

As a slight aside, but not a major problem, when you get to the output tests menu it looks like you can choose between selecting specific tests or cycling through all the tests (in this case for engine) it does not appear to be possible to select the individual tests option.

Tried VCDS output tests again - can hear very faint sound from N75 and N18 now, this time hooked up gauges.

 

Larger Draper Gauge which is part of vacuum pump is monitoring N18 output (EGR)

Smaller gauge is monitoring N75 output (Turbo)

 

Did check gauges against each other, small gauge is consistently reading only 1 inHg lower than Draper gauge.

 

Going to  try to attach video (not done this before so don't know if it will work)

Shows output test of N18 followed by N75, unfortunately I don't think VCDS on computer will be readable in video but you should see no movement for N18 test followed by the N75 test which shows the sort of output I had expected for both tests.

 

but are my expectations correct or am I missing something?

 

Thanks

 

Sorry - attaching video did not work due to file size.

Still image shows N75 test (ON) - needle at zero for N75 off.

Needle at zero throughout N18 output test.

On my phone here so struggling to read/see but is the gauge that you think is reading N18 vac definitely connected to the hose that goes to the top of the EGR?

On my phone here so struggling to read/see but is the gauge that you think is reading N18 vac definitely connected to the hose that goes to the top of the EGR?

Yes thanks.

The larger gauge is connected to the pipe that came off the top of the EGR valve.

But I have also traced this pipe back to the solenoid block, near the block the pipe is labeled P2 and it connects to P2 on the solenoid block. All the information I can find gives P2 as being to the EGR valve

 

See atachment

Latest attempt at working out what is going on.

 

Used T piece to connect an additional EGR valve in parallel with operational one.

 

Having tested both ERG valves I know they are very similar in relation to the vacuum at which they start to lift and the vacuum at which they are fully raised.

 

Aware that the external EGR valve does not have the pressure difference between both sides of the piston working on it, however the area of the piston is very small compared to that of the diaphragm.

 

Anyway as you can see from attachment, the external EGR valve is raised at cool idle. 

 

That can't be right - yes / no ?

 

Your thoughts appreciated.

Edited 15 May, 201610 yr by Octy0GG