Technical The Infamous Panda Misfire

[itsamugsgame]

My 2010 Panda 1.1Eco developed a misfire some months ago. Mechanics couldn't find the fault but I have finally sorted it.
The cables to the ECU should be clipped to the bracket for the ECU and the front one should also be clipped to the battery box. Mine weren't.
I then remembered that this started just after having a new clutch..
I cleaned the contacts as matter of course, attached the clips and started it. I could get it to misfire by jiggling the ECU cables.
I then secured the cables to the bracket with cable ties and success!
I've been running it for a month now with no issues. Maybe this might help someone else.

 

[Goudrons]

Yes, this is a very common issue that only seems to appear on the 1.1 models.
It's often first noticed over bumps and speed humps as the loom most move a bit.

There are a few threads regarding the problem.
On one, someone stripped the wiring back and found a Y joint that was weak.

 

[kmor panda]

Cable looms must be clipped down to reduce movement. The engine vibrates, and if the cables are vibrating in opposite harmonics to the engine, they will eventually break. The clips that the cable is clipped to is connected to the engine which forces the only vibration to be between the engine block and the engiine mounts. As a result, cables move with the engine which means that the cables do not flex.

One of the first way electricy was created was by moving copper in a magnetic field. Flexing cables can also do this and change signal levels to the ECU. Thus, you will have signals going and comming from the ECU that are corrupted which results in misfires / rich running / lean running and left like this, can damage the catalytic converter. An over rich running engine causes the catalytic converter to run too hot and overheat / breakdown. I believe that in the 1.2 engines, Fiat addressed this issue by increasing the grounding. It might be a good idea to check the earth straps in the car to ensure none have rusted at the bolts.