Not idling and misfire

i have C3 1.4-8v 2012
i have rough idling and misfire all the time the car goes into limp mode
also often the lights brighten up and down like the voltage regulator might be broken
but on the lexia the voltage is between 13.8-14.1 so that seems okay
back on the main problem
Changed the sparks ,ignition coil and timing belt still the same problem
i get error codes
P1340, P0304 excessive misfire on cylinder 4
P2140 fault lack of coherence between the accelerator pedal position and the point of resistance switch signal
P0620 - controlled alternator control fault

so i dont know if i have missed something or what is
the next step can it be the throttle body causing all this
i would appreciate any help thanks

Hi

mkcitroen wrote: ↑Mon Sep 02, 2019 1:27 pm but on the lexia the voltage is between 13.8-14.1 so that seems okay

Ignore that, test it with a meter or get someone with one to test it properly.
I have never seen lexia get the battery voltage right

mkcitroen wrote: ↑Mon Sep 02, 2019 1:27 pm P0620 - controlled alternator control fault

Definitely needs testing properly. Use a meter on the battery with engine running, then under electrical load and different RPM.

mkcitroen wrote: ↑Mon Sep 02, 2019 1:27 pm
P1340, P0304 excessive misfire on cylinder 4

Faulty injector?

But getting the voltage from the alternator checked and if necessary, fixed before any other electronic faults are investigated can save time.

Hey , thanks for the reply

I did check the voltage from the alternator it was no less than 14.2.
Did check compression on all 4 cylinders, the ohm resistance on all 4 injectors was fine i wi try to replace inj. 1 with no.4 so i can be sure its not the problem there

You have also mentioned some physical evidence of the alternator not behaving

also often the lights brighten up and down like the voltage regulator might be broken

So I would definitely get the alternator/electrical charging problem sorted first.

If the ECU gets a poor voltage it can give faults or an overvoltage can fry it.