Randomly unresponsive throttle

[cuprachris81]

This has happened a few times now, when I don't drive for a while I will start the car and when I push on the throttle nothing happens, then miraculously a day later it will start working again, I would appreciate any ideas anyone has as with my limited searching skills I cannot seem to find a threat thead?

I have a 2005 mk1 Cupra FR TDi if that helps...

 

[DanLlewhellyn]

Could be your throttle sensor? I believe they're controlled electronically on all the diesels so I'd check that as a first attempt. Also run a vag com scan on it, see if you get any codes come up!

Sent from my GT-I9100 using Tapatalk

 

[cuprachris81]

Thanks for the reply, I was wondering if an elm327 bluetooth adapter would work?

 

[DanLlewhellyn]

Well it wont give you any codes, unless your engine light is on, vag com provides all the codes really. However if you use the Torque app, you could use it to check throttle position. I dont see why that wouldnt work, but thats only really an option when the fault is occuring.

Sent from my GT-I9100 using Tapatalk

 

[cuprachris81]

Just been looking around the forum, something to do with water damage would make sense, and a wet ECU sounds most likely after the amount of rain we had before the fault occurred and then suddenly working again after the sun came out...

 

[cuprachris81]

I just started a new thread for this as I forgot I asked about it before.

Can anyone explain how to access the ECU and so I can check the connections do I have to unscrew the plastic underneath the windscreen wipers?

Any helpful suggestions or pointers to threads with help would be greatly appreciated.

 

[Gabster]

have a look at the thread with the cruse control retro fit.
It has many pictures and awesome guide to how to access the ECU

 

[cuprachris81]

I found 3 threads for 'retro fit cruise control' and none of them had the pictures, if you can you link the thread you had in mind here would be greatly appreciated, thanks

 

[cuprachris81]

This is nearest thing I have found, but more detailed information would help, thanks like what to do/check once the plastic cover is off, thanks.

http://www.seatcupra.net/forums/showthread.php?t=398729&highlight=ECU

 

[Gabster]

http://www.seatcupra.net/forums/showthread.php?t=359436

BTW its a sticky thread in this forum.
Go to the bit where he explains about the ECU.

I just wonder if putting it in gear and back to neutral when you have the unresponsive pedal would restart it.

I had a problem when while driving in random gear random speed the throttle would suddenly stop responding and the revs would go to idle.
Taking it out of gear and back and I'd get the response back.. I replaced the camshaft sensor and it got rid of that problems amongst other things.

 

[cuprachris81]

I put it in gear and back to neutral whenever I move it around so I don't think that will fix it, I have just got to the ECU everything seems dry, should I bother removing the ECU, not sure what I would do with it unless I am going to replace it and it does not come out as easily as I thought it would.

 

[cuprachris81]

For some reason my picture is not showing up https://goo.gl/photos/LLHE5ra1Q9su23ez5

 

[cuprachris81]

Thanks Gabster, got any links for changing the camshaft sensor? Else I will have a look once I have put everything else back together.

 

[Gabster]

Yes
Have a look at this video is done on a 06 golf but I done it myself on an ARL engine its the same

Part 1
https://www.youtube.com/watch?v=r4GzRBmhMO0
Part 2
https://www.youtube.com/watch?v=wU11Kl8BbrQ

I done it 2 months ago and took me about an hour all together 64 pounds for the sensor.
Seat quoted me for 320...

Just to add to that, the faulty sensor came up on a scan the dealer done for my car when it got serviced so I was kinda sure that I had to replace it.

 

[cuprachris81]

I found part 2 of that video but never found part 1 so thanks for that!

 

[Gabster]

Let us know how you get on

 

[cuprachris81]

I got the fault code P0674 from the ECU so there is an issue with one of the glow plugs, and there is also no throttle movement detected, could they be connected issues, a wiring issue? I suspect the glow plugs and the throttle sensor are separate issues but it didn't come up with a fault code for the throttle, is that normal?

 

[Muttley]

Wiring for glow plugs is entirely separate from the pedal position sensor wiring, so these are likely to be two separate problems. The glow plug one is either a duff plug or a bad connection in the plug harness.

When you say there is no throttle movement detected, what exactly tells you that? Bear in mind that diesels have no throttle. If you mean that the accelerator pedal movement is not being detected then this is a wiring or sensor issue - but the pedal position unit has two sensors in parallel so that a single failure is manageable.

 

[cuprachris81]

Sorry I am a bit of a noob when it comes to the engine, I was just using the torque app and under "throttle position" there was no response when I pushed down on the acccelerator pedal, do you know how to remove or the sensor? Could playing with it fix it or will it likely need replacing? I am yet to locate it, will I have to get under the car?

 

[Muttley]

OK. Looking up the Torque app and throttle position measurements it says

https://torque-bhp.com/wiki/Throttle_Position

"This is the reading from the potentiometer at the manifold - it is not a reading from the accelerator pedal"

So it is a red herring in terms of diagnosing your problem. Diesels have no throttle butterfly and so no potentiometer at the manifold (which in petrol cars senses the position of the throttle butterfly), they take in a full charge of air at every stroke and vary power by varying injected fuel quantity.

The pedal position sensor is in the box that the pedal is attached to, inside the footwell and attached to the brake/clutch pedal box. It has a six-way connector, three for each of the two parallel potentiometer sensors in the box.