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Paullap

Rough idle

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Hi , I have a wired one here, seat arosa 1.0 mpi  2008 , it runs rough and will not rev,   Codes , quite a few all to do with throttle position sensor, start the car and it misfires and will not rev, I put a second hand throttle body on, and it is the same, if I start the car with the throttle fully depressed. It starts revs and works fine, but I still have a engine management light on, when I try to clear the codes, 2 will not clear, and when I try to start the car it goes back to the misfire, I have to start it with the throttle fully depressed again, anyone have an idea what is going on?.

 

paul

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maybe it is the wiring going to the throttle body?

check all the fuses individually and then start stripping and untaping looking for breaks.

i predict under the battery tray.

codes would show a faulty item as it can't communicate.

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Hi Rich, Thanks for the reply, if it was a wiring issue, why would it all work ok when I start the car with the throttle fully depressed?.i am thinking more of the ecu.

Paul

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fault doesn't show till system is used.

go buy an ecu and throw some money where it isn't needed instead of taking some tape off.

have fun with that.

 

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Hi Rich, thanks for the info, just to recap, are you saying that if you clear the  trouble codes and some come back without the car running, it cannot be the ecu that is at fault, if that is true, that is a great help to me.

 

Thanks again

 

Paul

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ecu generally never fails, feel free to change and try.

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Update, I am still playing with this Arosa. I am  down to 3 codes

16792   EGR actuator (G212 Signal too high  P0408

17976  Throttle Actuator (J338)Mechanical Failure   P1568

17987 Throttle Actuator (J338) Adaption not started P1579

These can not be cleared they keep coming back and it wont let me do a throttle adaption while it still has codes

 

 

But this is the weird thing, I have found out by accident that if I start the car and it runs really  rough misfiring and no response to the accelerator pedal, I unplug the pre cat 02 Sensor and it clears and runs perfect. Leave it unplugged for an hour, I go back and start it,  it is misfiring and running rough again, Plug the 02 back in and it clears and runs perfect again, I can play around like that all day.    I do not think it is the 02 sensor because it would not do it when it was unplugged.   I am thinking it is as Rich said a while ago. I have wiring issues but where do you start looking.

 

 

 

Paul

 

 

 

 

Pau 

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Jsut follow the codes:

check the EGR valve is not jammed

Your new throttle body needs to run it's adaption routines see Ross tech Wiki on throttle body replacement

The O2 sensor is a red herring as such by un plugging it you are pushing the engine into limp home mode.

 

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Hi Thanks for the help. I have tried to do a throttle body adaptation but i still have fault codes.  am correct in saying these have to be cleared before i can do this . I was tring to do it on my Snap on Verus. I do have vag com, but not sure how to do it on this machine.

 

 

Regards

 

 

 

Paul

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Fixed, I have finally got to the problem, after testing the wiring for continuity, and trying to understand how it all works, I did a actuator test  on my Verus I think it was called on my verus, it came back with 2 problems . EGR valve and evap short to earth, I had not been testing for a short to earth. As I was doing this I noticed a connector block. I did not see this on the wiring diagram. Pulled it apppart and it was full of oil. It had been shorting out in the plug, you could see the 2 pins as where very black. I cleaned it up. Used the air line to blow it out. Put some electrical contact spray in it. And it now runs perfect. A long time to find it. But a fantastic feeling when you finally get it going.

 

 

Paul 

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pretty sure i was along these lines....

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