Check engine light and misfire after jump start

[Pieeaterdougie]

I'm new here so please be gentle with me!

The other day my battery in my mk1.5 Focus Zetec 1,6 was flat after too many stop-start short journeys.I got it jump started by a rescue agent using a pack (not jump leads) and he told me to take her for a run to charge it. Fair enough. After about 30 miles the check engine light started flashing intermittently (usually over 2000 rpm) and it felt like she was running on 3 pots. Limped home taking it easy,but by the time I arrived the light was constant. Now it won't go out when I start the engine. Has it been known for a jump start to cause this? Sorry if this is a daft question but I know hee-haw about ECUs and other such electrickery!

[jeebowhite]

its probably a done for battery. its spiking and dropping the voltage, which is likely to be affecting the alternator, which is probably then the electrical fault..