Engine misfire issues - how to fix?

[Hoppy_Frood]

Hello,

I have 54 plate Yaris Verso (1.3 autobox) but it's running like a bag of spanners. We took it to a local garage who diagnosed a misfire on cyl 4 but were unable to fix it. They tried a new coilpack but it made no difference. It's quite rough at startup but is ok until the engine is at operating temp, then the car loses power/judders a bit, the engine light flashes and some unusual noises can be heard. I love this car and want to keep it on the road as long as possible.

Based on the fact the problem is only really apparent when hot, the coilpack was the obvious culprit - but swapping it out made no difference so now I'm a bit stumped. 

Can anyone advise on how to fix?

 

Thanks

 

Iain

 

[flash22]

What error codes does it have ?, Has it had a compression test done ? Has the injector been checked/tested ? Have the plugs been checked/replaced ?,  These simple diagnostics should have been done at a decent garage