Surgeing Cure

[r1ch4rd]

I know it's not really a Ford but can you help me with this one as they are really the same vehicle in different make up.

I have a Sharan 2005 1.9 TDI with intermittent Kangarooing 1000-2000 rpm under light acceleration that you can stop by lifting or putting your foot down. I have read some forums who say this is common to the TDI engine and can be cured by removing the VSS wire that runs from the instrument panel to the ECU. Can anyone help out with a pinout for the 038-909-019-LQ EDC15P+ ECU so I can disconnect the wire at the ECU end rather than dismantling the dashboard.

Can any of you techy people help me out with a wiring diagram for this ECU? Or do you know of another fix for this?

Hopefully

Rich :rolleyes:

[insider]

The VSS is the Vehicle Speed Sensor which does not go to the ECU but direct from the sensor itself to the instrument panel (speedometer).

I can't see how removing this wire would solve your problem since it would just stop the speedometer from working!

Connections to the ECU (or anywhere else for that matter) are there for a reason, not to be disconnected to solve problems. You should look for the real cause of this problem.

[r1ch4rd]

The VSS is the Vehicle Speed Sensor which does not go to the ECU but direct from the sensor itself to the instrument panel (speedometer).

I can't see how removing this wire would solve your problem since it would just stop the speedometer from working!

Connections to the ECU (or anywhere else for that matter) are there for a reason, not to be disconnected to solve problems. You should look for the real cause of this problem.

Thanks Insider as you rightly say if you remove the VSS wire from the gearbox sensor the speedo will not work.

However there is a wire from the speedo to the ECU whose function is damping of turbo boost, but fast response to changes in load conditions is not one of its strong points. It is normal upon sudden application of load at higher engine speeds for the boost pressure to "spike" beyond its eventual setpoint, then drop below the ECU-requested boost pressure, then settle to a stable value after more fluctuations. This can be accentuated by the dual mass flywheel in the gear box chain affecting gearbox pulse timing.

Again you are right the ECU wire is there for a reason and the removal of this wire stops these fluctuations and consequent surgeing at the expense of a harsher throttle.

I have seen horror stories with people changing many different parts all of which may cause this problem, sensors, ECU, injectors, pump, turbo & pipes and valves costing hundreds of pounds and this problem not getting this cured hence thought I'd try the least cost option just to see first.

Rich

[insider]

Your symptoms and cure don't make sense to me. In your first post you say "intermittent Kangarooing 1000-2000 rpm under light acceleration that you can stop by lifting or putting your foot down".

In your second post you say "It is normal upon sudden application of load at higher engine speeds".

 

This suggests to me that you are experiencing the symptoms at low engine speeds / light load, yet your solution is for a problem at high engine speeds / high load?

 

I can't find a wire that goes from the instrument cluster to the ECU, except for the CAN bus. Obviously this links several modules and would not be one to disconnect!

If you think the problem is boost pressure related and caused by a slow response to demand then I would think it would be the actuators that are slow to respond, not the ECU. Perhaps you have a blockage in the vacuum pipes or a sticky variable vane mechanism?

[Smilge]

This sounds simply like a MAF problem to me although Insider is also correct in his diagnosis of your symptoms.

[r1ch4rd]

Thanks Insider

I do think you are right, there is a varying boost issue but the question really is how can the cause be identified from a host of expensive sensors and control devices. The vanes might be a problem but there is no particular pattern to this fault, let me describe exactly what happens:

Randomly sometimes in quick succession as you pull away in first gear and change to second with a medium accelerator depression you start to feel a gentle acceleration followed by deceleration every half second. Higher the gear the less pronounced.

This if you hold the accelerator pedal steady will build up to an undrivable heavy acceleration followed by deceleration every half second. This is accompanied by a pulsing turbo noise, like if you blip the engine and the boost back pressure is dissapated by the turbulent air around the turbo blades. (I have not found an air leak anywhere)

There are no warning lights showing so I would presume that VAG Com will not be able to identify the problem part?

Does VAG Com have the ability to display device paramaters or realtime outputs? Could this could maybe identify or isolate the source of fluctuating boost before resorting to serious dismantling?

Could this be an answer if so what version of VAG Com is needed to access the ECU on this car? 409.1?

Thanks

Rich

[f0ster]

hello

I have had this on an earlier model galaxy, it was caused by the boost control circuit, mainly the vacume pipes

that control the boost were partially blocked by oil, also the n75 valve, replacing all pipes and valve cured it, not saying this will cure yours but there you are.