Loss Of Power

[Guest Ceskahawker]

I have an 'R' Reg 1.9 TDI and occasionally the power drops and the throttle has no response, when this happens stationary the engine revs to about 2000 rpm pushing the throttle has no effect, turn the engine off, restart and all is well until the next time it does it, same when travelling switch key off and on again and all is ok again, anyone experienced this, or know what could be causing this, any help aprreciated

Many Thanks

[Topbloke]

as far as i am aware this vehicle is drive by wire ie no throttle cable just a throttle potentiometer try checking the pedal pot wiring, may just be a poor conection there could be a dead spot within the the pedal pot the only way to test that would be to hook the vehicle up to a computer/diagnostic reader and check the live readings as you push the pedal down

[Guest Porker]

This is exactly the symptoms I am having on my Alhambra. Unfortunately I have had this for over 12 months!! 8 visits to main dealer - no result. (BTW a new engine hasn't made any difference)

 

I have just changed main dealer and they are looking at it. The work I have had done (which made no difference) is :

 

Multiple MAF changes (apparently the fault logs as a MAF fault but the new dealer thinks it is not the sensor)

Needle valve (no idea which one)

New vacuum pipes.

Current theory - possible carbon build up on turbo causing sticking blades vanes.

 

Sorry I know its not much help but if I get it cured I will post here.

[Guest SA Intruder]

Carefully check the throttle pot and wiring.

 

There should be 0 to 5Volts from it when the pedal is operated through its entire stroke. It should be very linear.

 

When the track gets worn, the output becomes erratic and the ECU will ignore inputs and revert to idle until the ignition is switched off - then it will work until the pot acts up again and repeat.

[Guest Ceskahawker]

Many thanks to all responses, Although I have not checked the pedal pot (But will) I do not think it will be that as to my way of thinking if it had a worn track pushing the pedal would cause it to clean it, similar to spinning a dirty volume control on a radio for instance. and the fault sometimes occurs on start up as well as travelling, I have since spoken to a mechanic, who is not terribly up to date with modern vehicles, having left the trade some 15 years ago, but he told me that he belives that on this type of system there are relays that are in the circuit that sometimes get sticky and turning off and on the ignition refires the contacts, sounds feasible just need to find out if one of the relays has the throttle pot going through it, anyway if I find thew fault I will post the answer here, but the throttle pot will be the first thing I check. Many thanks once again

[Topbloke]

the throttle pot has two tracks within it one track runs 0 upto 5 volts track two 5 down to 0 volts not only backing each other up but if one circuit go's u/s it still has a the other, they should not go through a relay it should go direct to the ecu,from there to the throttle body motor hope this sheds a little light . talking of lights doe's the engine management light come on or the glowplug light when the fault is present ?

[Guest Ceskahawker]

Thanks topbloke I will check, not sure about the light I will look next time

Regards