Loss of power, accelerator pedal shudder, check engine light

[red squirrel]

I have a 2009 i30 cw 2.0L automatic petrol wagon with about 70,000km serviced regularly.

When idling and/or reversing at slow speeds car sounds and feels normal.  When starting to accelerate, if accelerator pedal is pressed slowly car accelerates slowly, quietly & smoothly but if accelerator pressed to accelerate more rapidly: pedal shudders and car accelerates very slowly instead of normally.  Check engine light is now solid when stationary but is either flashing or solid when moving (the light, power issues and shuddering just started today).  Car has no power going up a hill.  Ideas?

Also possibly relevant: over the last few months it has been driving fairly normally but occasionally it has felt like gear changes were ‘dragging’ or lagging and on very rare occasions if you tried to accelerate quickly the car would loudly ‘thud’ into the next gear.  After the 'thud', gear changes ran a lot smoother for some time before starting to lag again.  I believe this has happened since the inlet/intake manifold was decarbonised a few months ago but not 100% sure.

[Dazzler]

Welcome Red Squirrel, Sorry to hear of your troubles.

I'm no mechanic but it sounds like the transmission is failing in some way which is putting a strain on the motor generating the light. I assume you have checked the engine oil and water levels and have been keeping an eye on the engine temperature. 

I could be completely wrong, there are far more savvy technical people on this site who will hopefully give some feedback soon.

[tw2005]

Could be another valve body failure but I'd get an OBD2  reader and write down what codes are logged. Trans is in failsafe, locked 3rd I'd say when the light is on. Have you had it from new? Hard to believe 70000k and it's broken

[red squirrel]

Yes, have checked engine oil and water levels and always keep an eye on the engine temp but it has never been an issue.

[red squirrel]

Yes, had since new and both of us drive it smoothly.  Lost our enthusiasm for speed a long time ago plus there isn't anywhere to drive fast legally and safely anywhere near us.  Hasn't actually reached 70,000 yet.  Will try to get a reading soon - won't drive it til then though. 

[nzenigma]

feels normal when idling, reversing at slow speeds  & pedal  pressed slowly car accelerates normally

 accelerator pressed to accelerate more rapidly pedal shudders ??? (illusion?  ) car accelerates very slowly .

 no power going up a hill.

Check engine light is now solid when stationary but is either flashing or solid when moving

 gear changes were ‘dragging’ or lagging and on very rare occasions
  After the 'thud', gear changes ran a lot smoother for some time before starting to lag again.

Squirrel you are the only person who can answer the obvious: The engine light is on, what are the codes being thrown up or stored?
From there, hopefully, we can give more informed advice.

Taking a guess,  lack of power probably =temporary limp mode.

Could be another valve body failure but I'd get an OBD2  reader and write down what codes are logged.  YES

Trans is in failsafe, locked 3rd I'd say when the light is on. Have you had it from new? Hard to believe 70000k and it's broken

Young car and symptoms are "very rare",  why mention valve body failure? 

[tw2005]

feels normal when idling, reversing at slow speeds  & pedal  pressed slowly car accelerates normally

 accelerator pressed to accelerate more rapidly pedal shudders ??? (illusion?  ) car accelerates very slowly .

 no power going up a hill.

Check engine light is now solid when stationary but is either flashing or solid when moving

 gear changes were ‘dragging’ or lagging and on very rare occasions
  After the 'thud', gear changes ran a lot smoother for some time before starting to lag again.

Squirrel you are the only person who can answer the obvious: The engine light is on, what are the codes being thrown up or stored?
From there, hopefully, we can give more informed advice.

Taking a guess,  lack of power probably =temporary limp mode.

Could be another valve body failure but I'd get an OBD2  reader and write down what codes are logged.  YES

Trans is in failsafe, locked 3rd I'd say when the light is on. Have you had it from new? Hard to believe 70000k and it's broken

Young car and symptoms are "very rare",  why mention valve body failure? 

You're right, how naughty of me I should have included these as possibles.

 P0605
 CHECK SUM ERROR

 P0708
 TRANSAXLE RANGE SWITCH CIRCUIT HIGH INPUT

 P0716
 A/T INPUT SPEED SENSOR RATIONALITY
 
P0717
 A/T INPUT SPEED SENSOR CIRCUIT - OPEN or SHORT(GND)
 
 P0722
 A/T OUTPUT SPEED SENSOR CIRCUIT - OPEN or SHORT(GND)

 P0731
 GEAR 1 INCORRECT RATIO
 
 P0732
 GEAR 2 INCORRECT RATIO

 P0733
 GEAR 3 INCORRECT RATIO

 P0734
 GEAR 4 INCORRECT RATIO
 
 P0743
 TORQUE CONVERTER CLUTCH CONTROL SOLENOID VALVE - OPEN or SHORT(GND)
 
 P0748
 VFS SOLENOID VALVE CIRCUIT - OPEN or SHORT(GND)
 
 P0750
 ON/OFF(SCSV-A) SOLENOID VALVE CIRCUIT - OPEN or SHORT(GND)
 
 P0755
 PCSV-A(OD＆LR ) SOLENOID VALVE CIRCUIT - OPEN or SHORT(GND)

 P0760
 PCSV-B(2-4 SOLENOID VALVE) CIRCUIT - OPEN or SHORT(GND)

 P0765
 PCSV-C(UD) SOLENOID VALVE CIRCUIT - OPEN or SHORT(GND)
 
 P0880
 TCM POWER SIGNAL ERROR

[nzenigma]

Why are you stuck on the transmission? Have you been doing Farcebook?  Is this the FB need to just say something, anything irrelevant will do?
Stop it!!!!!!!!!!!!!!!!!!!!!!!! 

Mate, with respect to the OP, the lady feels that the accelerator pedal shudders ????????? Other sensations relating to transmission clunks are rare.
An engine misfire could be interpreted in the same way by a non-technical person.
Lack of power on a hill also possible bad engine?

[tw2005]

Why are you stuck on the transmission? Have you been doing Farcebook?  Is this the FB need to just say something, anything irrelevant will do?
Stop it!!!!!!!!!!!!!!!!!!!!!!!! 

Mate, with respect to the OP, the lady feels that the accelerator pedal shudders ????????? Other sensations relating to transmission clunks are rare.
An engine misfire could be interpreted in the same way by a non-technical person.
Lack of power on a hill also possible bad engine?

I'm bored

[nzenigma]

Why are you stuck on the transmission? Have you been doing Farcebook?  Is this the FB need to just say something, anything irrelevant will do?
Stop it!!!!!!!!!!!!!!!!!!!!!!!! 

Mate, with respect to the OP, the lady feels that the accelerator pedal shudders ????????? Other sensations relating to transmission clunks are rare.
An engine misfire could be interpreted in the same way by a non-technical person.
Lack of power on a hill also possible bad engine?

I'm bored

I noticed 

Im spending the weekends in 39 deg heat fencing a 100 acre farm on the side of a mountain. Barbed wire hates me. Wish I was bored!