Weird throttle problem - no control over revs. Car doing it's own thing.

[vibeone]

Weird one, that isn't very serious but I'd like to sort.

mk3, 2.0 tdci 140 2011...

Car is stationary, out of gear. I lightly press my foot on the accelerator, and the revs slowly increase (lets say to 1k).  I keep my foot at exactly the same point, but the revs continue to increase (approx 1.5/1.8k) without me applying any more pressure before eventually dropping quickly back to where it was.

I've also noticed this when pulling away.  Sounds like I can't drive - but it's not me doing it.  It's not everytime, and appear to be when I lightly dab the accelerator pedal (so doesn't occur when I pull away quickly).

Any ideas?!

[alexp999]

Might need a PCM update.

My 2012 2.0 TDCI was really unpredictable until I had it updated, if I tried to adjust the throttle from it overrevving it would then cut all power and lurch like I'd hit the brakes. Othertimes I'd go to make a quick get away and get nothing.

[Phil21185]

Could it be the throttle position sensor going kaput?

[vibeone]

Already had the PCM update which *seemed* to fix it for a while, but it came back.  It's not as bad, but still does it.

Tell me about the TPS... seems a common fault but not sure the symptoms match up?

 

Thanks!

[Phil21185]

1 hour ago, vibeone said:

Tell me about the TPS... seems a common fault but not sure the symptoms match up?

 

Well in fairness, no not exactly.  My friend's Ka used to overrev massively when he pulled up to roundabouts etc and that was the TPS going.  Others have had similar symptoms with faulty TPSs. 2 things might be helpful here:

1, someone on these forums with better mechanical knowledge than me =]]

2, perhaps an elm and software that could tell you what the TPS is reading in a live situation?

[vibeone]

I guess I may just need to take it in, just wondered if anyone else had the same or similar issues.

It's kinda like the anti-stall is a bit over-sensitive?

[kpg]

Mine is kinda like this. At time when I'm in gear at a steady speed, the acceleration feels all jerky. The revs go up and down very noticeably. It's not bucking too and fro but it is uncomfortable. other times depending on what im doing with the clutch, I put my foot down to get going and nothing happens for like 2-3 seconds then a whole heap of revs for no reason. I've had the pcm update as well. Wondering if it is to do with throttle position sensor.

[vibeone]

On 6/28/2017 at 5:19 PM, kpg said:

Mine is kinda like this. At time when I'm in gear at a steady speed, the acceleration feels all jerky. The revs go up and down very noticeably. It's not bucking too and fro but it is uncomfortable. other times depending on what im doing with the clutch, I put my foot down to get going and nothing happens for like 2-3 seconds then a whole heap of revs for no reason. I've had the pcm update as well. Wondering if it is to do with throttle position sensor.

I think I'll let it get worse then take it in for them to diagnose but with some pointers towards the tps.

I also considered EGR valve - but not sure where it is on the mk3 2.0d 140 - car has done 30k since 2011, so the EGR has probably had a hard life I imagine.

[vibeone]

Took a video if it helps.  This is me with the car stopped out of gear... Basically trying to press the pedal to get to 1k revs at first, then holding it completely stable after it immediately jumped above that point.  The increase to 1.5k  isn't me, the decrease back to 1 also isn't me moving.  Then it settles, and I can then increase revs to just below 1.5k (At the end) normally.

Thing is it does this when pulling away sometimes and it sounds like I can't drive since the revs increase far more than I want or need :(