Good evening

 

I have been searching through this forum now for a while trying to find a fix for my Scout.

 

The car is a 2008 Octavia scout, diesel, with a manual gear box.

 

 

What started happening about six months ago, but has since gotten more and more frequent, is that while driving along the gas pedal just dies.

When the pedal dies I can do whatever with it and nothing happens, that is untill I tap the brake, touch the clutch and then it comes back to life and works as normally, that is untill it does it again.

When it dies I can also set the cruise control and the car drives like normally and after canceling the c/c the gas pedal is back in business.

 

This started, as said, roughly six months ago, but has now started to get more frequent. Might be the cold. At first it mostly happened after having driven at a more or less constant speed for say ten, fifteen minutes, at least. But now it happens much more often and can just as well happen in city traffic.

Also at first I mostly noticed it hapening in sixth and fifth gear, but now it happens in any gear. Haven't had it in reverse though.

 

The car is not giving off any fault codes, so that doesn't help.

 

After going through the forum I found that the brake pedal switch might be to blame. So I had that one replaced today, but apparently it happened again earlier while my girlfriend was out driving.

 

So it seems I am back at square one.

 

Do any of you have any good advice on where to start looking now. Could it be corrosion in some of the wires maybe or are there any other sensors I might have to look into?

 

 

Andri

Have you it scanned with the dealer tool or VCDS or some other fault code reader?

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Check for water ingress into accelerator pedal sensor. Read throttle position through measured values and cross reference that to pedal position whilst driving. Compare results when fault occurs. Check egr position when fault occurs too.

Check condition of throttle body and egr. Remove any carbon deposits or large amounts of oil if any are present. Recalibrate throttle then try again.

That's where I would start.

Dale

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Have you it scanned with the dealer tool or VCDS or some other fault code reader?

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I just had a independent garage scan it for codes, and they came up with nothing.

 

 

 

 

Check for water ingress into accelerator pedal sensor. Read throttle position through measured values and cross reference that to pedal position whilst driving. Compare results when fault occurs. Check egr position when fault occurs too.

Check condition of throttle body and egr. Remove any carbon deposits or large amounts of oil if any are present. Recalibrate throttle then try again.

That's where I would start.

Dale

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I have no idea how to measure throttle position vs. pedal position, so I guess getting a service manual might be a good start then.

 

 

But with the way the pedal dies it definetly feels like something electrical cutting out.

Engine runs like normally but just does not respond to pedal movement at all. That is until "reset" by braking or disengaging the clutch.

I just had a independent garage scan it for codes, and they came up with nothing.

 

 

 

 

 

I have no idea how to measure throttle position vs. pedal position, so I guess getting a service manual might be a good start then.

 

 

But with the way the pedal dies it definetly feels like something electrical cutting out.

Engine runs like normally but just does not respond to pedal movement at all. That is until "reset" by braking or disengaging the clutch.

 

A generic code reader may not pick up all faults.

 

Using VCDS or the dealer tool you can "read" the pedal position in real time.

I think I am correct in saying that the throttle control is overruled by the brake pedal signal on Octavia's? Correct me if I am wrong.

 

Are you sure it is not a problem with the brake pedal sensor,

 

I have seen it on a friends Picasso where the brake pedal sensor was breaking down and the brake lights were flickering on/off, he wasn't aware of this (i observed it while following him), but he was aware that when the car thought the brake pedal was being depressed it over rides the throttle pedal and he had a similar effect to what you are experiencing. The throttle pedal having no effect.The car does not expect you to accelerate and brake at the same time, so braking takes president and ECU cuts the throttle pedal signal.

 

It may not be this - but just an idea to explore.

 

 

Lewwy

 

I think I am correct in saying that the throttle control is overruled by the brake pedal signal on Octavia's? Correct me if I am wrong.

 

Are you sure it is not a problem with the brake pedal sensor,

 

I have seen it on a friends Picasso where the brake pedal sensor was breaking down and the brake lights were flickering on/off, he wasn't aware of this (i observed it while following him), but he was aware that when the car thought the brake pedal was being depressed it over rides the throttle pedal and he had a similar effect to what you are experiencing. The throttle pedal having no effect.The car does not expect you to accelerate and brake at the same time, so braking takes president and ECU cuts the throttle pedal signal.

 

It may not be this - but just an idea to explore.

 

 

Lewwy

Yes that is something that I had read on here earlier, so I had the sensor changed. But apparantly it's still the same. I haven't driven the car personally since it was changed since I'm away for work.

So I have been doing some work on this for the last few months with no luck.

In the meantime the problem has gotten slightly worse but the car is still driveable. It did get worse during the coldest winter but with the weather warming up it is better but far from good though.

I have now changed out the brake pedal sensor, throttle pedal itself, checked the pedal plug for corrosion as well as the ECU plugs. They all looked nice and clean.

As stated all these things did nothing.

It appeares that it is worse in damp weather and the cold. But with a few dry days outside it does feel better. That is the throttle dies alot less then.

Most common rpm where the throttle cuts out seem to be around 1700 and 2200rpms. But that might also simply be the most common rpms I'm running it at.

I was thinking this might have to do with vibration messing with a faulty wire, but I just don't know anymore.

Since the cruise control works flawlessly I can only think that the problem has to do with wiring between the throttle pedal and ECU or the ECU itself.

Does anyone on here have a wiring diagram and is willing to share it for me to be able to try to track down the wires for inspection.

Also is it possible to open up the ECU and see if there is any corrosion in the box.

To my knowledge the ECU hasn't been opened up previously, but who knows on a second hand car. But with the fault being worse in cold and damp makes me afraid that there might be water getting into the ecu box.

Andri

Hi Andri, 6 years later. I have a 2008 Octavia 1z5 1.9 TDI 5 speed manual wagon/combi (185k km's) with exactly the same symptoms as you described. 

 

While cruising at constant revs 1800 to 2200 rpm in 4th gear the accelerator pedal electronically disengages and if left the motor decelerates to 900 rpm, and will continue to run at these revs. As soon as I change down a gear the accelerator immediately reengages and away I go. This does not occur when using the cruise control (which I use a lot!). I have a good quality ELM327 and have tried a number of OBD2 Apps. The diags on all give no fault code numbers.  

 

This is clearly an electronic glitch. My initial goto, the EGR valve, is clean as a whistle.

 

So, how was your issue ultimately resolved? 

 

Many thanks

 

Kevin

 

 

On 13/11/2014 at 04:50, Andri said:

When the pedal dies I can do whatever with it and nothing happens, that is untill I tap the brake, touch the clutch and then it comes back to life and works as normally

 

Could the clutch pedal sensor have anything to do with this fault?

The throttle pedal is "fly by wire". Although the pedal position sensor has been known to fail, I would first check the connection at the pedal sensor for a loose/dirty connector.

Try disconnecting the battery for a minute.

 

Whilst waiting, turn the ignition on and activate the horn/high beam flash to deplete any residual charge.

 

Reconnect the battery with the ignition still switched on.

Thank you Micmac, Picpilot and Erindad. In order, I will check and clean the pedal sensors first, and then do the battery disconnect reset/ reboot, for elimination. 

Well, 2 and a bit months later. I "jiggled" the accelerator connection back in June, but did not disconnect or otherwise tamper. The issue has not reoccured.  

 

I will report further if I do get a recurrence.

 

Now dealing with an indicator stalk that flashes left when I lift to turn right...! I am replacing the stalk...