Engine: TDI: Slow return to idle

[ajm]

I think you've quite possibly found the source of your trouble - it looks like a new sensor is about £40 so not an unreasonable amount to "risk" given your troubleshooting to this point.

[slimeslab]

Gotta be worth a try I think.

It would be good to know what the system is supposed to do using the clutch sensor data? Especially on a car without cruise control...

[brickman]

Never knew that about the clutch pedal sensor, assumed its only role was for the C/C.

Suggest dismantle it and clean out with spray, could just be gunk, though a new one isn't as much as I'd though it would be.

Ilexa's software gives me a throttle value from 0-100%, hence assuming its resting value was 0% Guess the Ilexa software is interpreting the 9-88% Will have to get VIDA working as sounds like it offers more info!

[slimeslab]

Vida is damn useful but I find that its info is spread all over the place and you have to sort of learn the way around the database.

Does anyone have this same car with this same engine who would be willing to film or describe how their car returns to idle so I can compare please?

I took the sensor out and had a look and when I put its two halves back together again the track snapped into many many pieces :/

So...i'll be ordering a new one Monday morning regardless as I now have an engine warning light on constantly

[brickman]

If I'm out tomorrow I can do one for you. Are you talking just from rev's, lift off throttle in neutral, or do you mean whilst driving?

[slimeslab]

In neutral would be great.

Mine exhibits the same fault whether in neutral or while driving and dipping clutch.

It would just be good to see someone else's car to do a comparison

Thanks.

[slimeslab]

Update on this - new clutch sensor picked up today from FRF Swansea - better price than eBay.
Have fitted it but haven't reset the ECU yet, I have also taken the plunge and removed the inlet manifold to clean it out along with the EGR (stoopid thing)

It was full of sludge, so far its had two Mr Muscle oven cleaning foam soaks and pressure washes and its now soaking overnight in Gunk degreaser.

Its amazing the size on the chunks of oily sludge that came out, its just an awkward thing to clean due to the shape.

So hopefully once its cleaned out and dried tomorrow I'll be able to test everything.

Fingers crossed.

[artiedtke]

Hmmmm... pedal sensors....

Try this...

Keep one foot on the brake, then rev up the engine with the other. On mine the revs take longer to drop like this.

Don't know why, i think it's something to do with the cruise setup and the pedal switches.

I noticed this while waiting in traffic once holding the car on the foot brake and could hear a noise from somewhere, which is when i blipped the throttle with my heel (to see if noise increased with revs) and noticed this behaviour.

Also to try and diagnose brake issues (pulling, pulsing etc) when in gear, try applying the brake and throttle at the same time... you cant. The car will cut the throttle when it realises the brake is applied.

[slimeslab]

Update:

Manifold cleaned along with EGR.
New clutch position sensor fitted.....
Exactly the same symptoms and problem exists....

I have checked the clutch position values that are being reported in VIDA and the exact same behaviour is being exhibited - resting value of 30 odd % with a max of 80 odd with a jump from 50-80ish.

The resistance values in VIDA:

Position (mm) 0 25 50 100
R (() 1500-2500 1000-2000 750-1750 500-1000

Are not a great deal like my readings - my 0mm position is open circuit and my final 100mm position is about 350 ohms.

There is a sudden drop in resistance in the last 20mm of movement which is (I'm guessing) the jump reported my the ECU.

I'm totally confused now - could the new sensor be faulty?

But its odd that the old sensor and new sensor exhibit exactly the same values and behaviour.

HELP

[Chris_Rogers]

Have you measured the actual resistance of the sensor over the operating range using a multimeter?