Hello, thank you very much for supplying the information about the ecu for punto mk2. 1.2,16v. I am trying to understand why my punto seems to run in limp mode. It smells in the car when it runs badly like burning, either wire or plastic but I can’t trace it. The problem starts when I turn into a corner weirdly. I am looking at it tomorrow.
If it smells in the cabin like burned plastic this is usually because one connector is burning due to bad connection and therefor increased electrical resistance. The connector that you should check 1st is a heating resistor connector. You know you have ventelation in this car and you can turn it on 0 or 1 or 2 or 3 or 4. When you have 0 or 4 there is everything okay because there is no electrical current trough this resistor ( 0 becase its not running at all, 4 the current bypasses this resistor). Usually the biggest problem is 3, becase there is largest current trough this resistor and the connector on this pin used for this gets coroded 1st. Shortlly after this, if you still use the ventilation on number 3, the whole connector is getting melted and burned, even if you buy the new heating resistor, you still have bad connector on other side, so thing i recommend here is to cut this connector away, throw it in garbage, and connect the wires without connector, preferly by good soldering, thick solder connections and over it add protective tape or shrink wrap. This connector can be found where passenger knees usually are. The resistor is sticking inside of ventialation chamber because inside there is moving air and it uses this air for cooling itself down. This is also why you have to be careful that your cabin filter is not clogged. So as said the main body of this resistance is inside this ventilation chamber, but the connector we are talking about is sticking outside, so, down to the foot of the passanger. And the other part of connector - the one with wires comes to it. So just take this conncetor of and you will immediatly see if it is in good shape or is everything here burned. Anyway I hope i guessed your problem - if its not this, remember that only very high current can cause such heating and you only need to check these. Meaning, there should be nothing wrong with ECU because there are all the lines with very little current. In this car, until now I only found this trouble that i am mentioning above. Other lines i can think to check are red cable from car battery to the fuse box, is it in good condition, does it heat up when you have a car in idle? Main ground connection from the car battery down to the gearbox? - you have to remove the car battery and the box for carbattery to get down to the connection to the gearbox.
About missfiring, remove the passanger front wheel, remove the inned plastic guard/fender, remove the guard for serpentine belt, take the serpentine belt off (you take it off by trying to screw bolt on serpentine tensioner even more - bolt 13mm head), remove 3 scews 13mm from the serpentine pulley (when you will be puttin it back notice a little pin here - it can only be turned this one direction), support the enginge from the bottom - you can putt some wood under the oil can, and lift the engine 1cm, undo the all 6 nuts at the top for the engine holder on passenger side (this is under the hood, near where big spring nut is at top), now next step is a bit tricky because there is not much room here, if you need a bit more room, you can lift the engine up from bellow a bit more, 5 or 10cm, so you need to undu 6 horizontal screws that are in the bottom part of the engine holder, they are all the same - 13mm head. Then undo plastic cap of the timing belt - one screw at top 13, one screw towards front of the car 10, and one screw in middle of the bottom half 10, remove the cap for timing belt, check timing tensioner, does is still hold? At the bottom you have induction sensor that is reading teeth at the previously removed serpentine pulley. Make sure there is no metalic, iron dirt on this sensor - so wipe it a little, and also check your pulley if it has no metalic, iron, ferite dirt or maybe even broken one tooth. The next thing is, this sensor is sending this date trough wires that goes trough the plastict cap of the timing belt, please check if these wires are in good conndition. At the beginning of engine lifetime there is usually some protection around these wires, but usually withing 10years it degrades, so add some protection to these wires back. After checking all this and assemblying it back, I expect the motor to have 0 missfires. If you find the tensioner a bit loose it is possible that the timing is off for a tooth. Its possible to align it back with some tools, or even with just a picture of the tool, so i wont describe this until you say its needed. I never had a problem of it being missaligned for a tooth, but i had a problem that i was drilling something above this motor and one sharpenel from drilling fell down right in between that induction sensor and the serpentine pulley. So i believe the ECU is giving spark timing according to this lower induction sensor. But you should be aware that there exists one more. At the top of this engine, between 3th and 4th spark plug there is also one induction sensor for inlet camshaft, that also serves for some timing corrections for sparks and injectors, but it plays smaller part, if you have such large missfires there is either a problem with the one at the bottom or with you even have a missalgiment in timing belt. If you get until here and still with a problem, you can try replace both of the sensors.
What do you mean by "I have borrowed a icarsoft scanner and no codes found and not a clue what’s wrong". On this car every missfire gets recorded, and when reading errors, you should see missfire cylinder 1, or 2 or 3 or 4, or combiantion of more of them.
you mentioned you changed many parts already, did you also do the ignition coil ?
Did you remove throttle valve and clean it inside where air is passing trough ?
your catalyitic converter, does it have heat shield in front of itself? These cars have aluminium heat shield and on holes where it is attached it usually corodes and the shield falls away, but this heat shield is a crictical component for this engine - only if the catalytic converter is properly heated 02 sensors are working correctly.
How do you know your car is in a limb mode?
Do you have your engine light on? I assume you should - but then why are you saying you see no error codes - get the error codes with obd diagnostic tool and report more about your problem so we can solve it. If you dont know how or something, we can work on this 1st..
Please come back with more info about problem or with info how you solved it and what it was.