Hello,

2009 MY10 Skoda Octavia SCOUT wagon Diesel 2.0tdi, BMM, 6spd manual, 200K km, Australia.

Normally car ran well in the mornings, and then late morning and for the rest of the day it had the problem.

Car always starts easily and idles without problems, no misfires.

No smoke on start up or idle, only smokes under acceleration, and no smoke in mornings or when it runs well.

I removed negative battery cable, let sit for 30 minutes to reset ecu, car ran well for 1 day (morn, ave, night and following morn) then problem returned.

I removed and cleaned MAF sensor with MAF cleaner, car ran well for 2 full days, then problem returned.

Anyone any ideas,

Thanks.

Edited 14 October, 202514 Oct by AusAds

Are you able to read live data? check turbo boost figures.

20 hours ago, Warrior193 said:

Are you able to read live data? check turbo boost figures.

Hi, thanks for that. Can you recommend a good free scan tool ap for android, I am using Car Scanner and it's not the best, and I am not that good at reading data.

Anyway, thanks for your comment, yesterday I started looking at stuff/data/sensors in Car Scanner and noticed that the throttle position sensor was at 94.9% at idle, as I revved the car the other sensors showed normal movement but the TPS stayed at 94.9%.

So today I took some parts off the engine to get to the throttle body, yes the throttle flap is in the open position (obviously with the car turned off). My understanding is that this flap should be closed at engine off and only slightly open at idle?

I could not take the TB off because it's got some god forsaken triple square spline 12 point bolt on it x3. I think the bolt is M6 not certain if its spline or triple square?

TB was fairly clean but I sprayed it heavily with carby TB cleaner and let sit for 15 minutes whilst I swore at the bolt. I also gently moved the flap close open a couple of times, and it moved smoothly, it wasn't sticking on anything and the servo/motor didn't feel stuck either. I am wondering if the sensor is dirty/shot? I think I need to remove TB to get sensor out as it's all pushed up against the back of engine bay.

I have massive problems removing D type connections for sensors, do you know how to remove this one, bottom of open flap pic? Where is the magic button you have to push/pull/twist?

I haven't had any engine faults red or orange regarding this problem, its been running rich for a month+ but no codes.

My new engine air filter had arrive so I installed that, Drove car and it had typical problems and after 10 minutes of driving I got my first orange warning light on dash (Coils/glowplugs - which can mean 1000 different things), I tried to code read but nothing was showing, and it cleared from dash when I turned off and restarted. Car drove well without problem (but sensor still showed TPS open at 94.9%).

Later today I will do another ecu reset by removing neg battery terminal.

(also this car has the goes into limp mode when driving on highway at speeds greater than 90kmph - but that's another problem).

Edited 15 October, 202515 Oct by AusAds

Sorry, I can't recommend a suitable free app, I use a OBD2 scanner (Autophix OM126P) purchased last year to diagnose a turbo actuator problem with SWMBOs Fabia.

It's only a fairly basic tool (no adaptation ability) but can read live data.

Your problem does look like an issue with your TB control.

They are triple square by the look of them. As said maybe the throttle body? but might be bad pattern injectors. Try a tank of supreme diesel and also some injector cleaner as well. The limp mode sounds like my old 1.9tdi. In my case the actuator on the turbo was stiff and caused overboost at higher speeds. I sprayed with oil and manually operated it until it free off. Just before it went into limp mode it made a very slight blow off sound.

Alasdair

Just wonering if its a failing exhaust sensor? It might be connected to the rich running although I would have expected fault codes EML light. Is there anyway you could get it scanned with VCDS it may well pick up codes a generic scanner misses. I think as well the throttle body flap should be almost closed when car isnt running. Good luck

Thanks guys,

Would bad injectors cause misfires also? I really don't want it to be injectors because $$$

I am assuming that the throttle flap always being open at 94.9% would cause air fuel ratio problems?

Failing injectors can cause misfires and bad pattern/clogged nozzles can cause black sooty smoke and low power plus poor mpg but if the throttle flap isn't moving then I would start there. It may be the wiring to the throttle body?

Alasdair

Thanks, need to buy more tools to get TB off, also another nightmare D connector will not come off

NOPE NOPE NOPE, throttle body flap or TPS was not the problem.

The wastegate actuator was stuck, used penetrating oil and got it moving again, seems to have fixed these issues.

Edited 19 October, 202519 Oct by AusAds

2 minutes ago, AusAds said:

NOPE NOPE NOPE, throttle body flap was not the problem.

The wastegate actuator was stuck, used penetrating oil and got it moving again, seems to have fixed these issues.

You made a school boy error! Diesel cars do not have a throttle valve to control engine speed like a petrol does, they only have them for EGR and anti-shudder purposes.

Glad you got there in the end!

lmfao thanks for the help