Coil pack

[Rakiwhite75]

Can anyone tell me symptoms if the coil pack is breaking down I have Ford Focus ST 2010 has been modified it’s 350bhp it’s this makes any difference...also new battery and alternator which were both done just over a week 

[Luke4efc]

It's much easier if you tell us what symptoms you have and we tell you possible faults lol. 

Rough idle/ misfire are usually the result of a failing coil pack. However a rough idle and misfire can be the result of many other faults too. 

[Rakiwhite75]

Rough idle misfiring won’t tick over at all starts lovely but doesn’t want to stay started I have been told it’s coil pack so I’m going to get new ones 

[Luke4efc]

46 minutes ago, Rakiwhite75 said:

Rough idle misfiring won’t tick over at all starts lovely but doesn’t want to stay started I have been told it’s coil pack so I’m going to get new ones 

Those are the injectors lol. The coil packs are on top of the engine underneath all the plastics.

I'd change the spark plugs before the coil packs, the coils on these engines are pretty solid and rarely need replacing. Just check when they were last changed first. If they're a good few years old then worth changing as part of a service.

Have you no fault codes? Usually a misfire will trigger at least 1 code telling you which cylinder(s). My advice is don't go changing bits willy nilly in the hope it will fix it. A rough idle can be caused by so much other than coils. A genuine Bosch coil will run you about £50 each (x5 = £250) that might not even cure your problem.

[Rakiwhite75]

Cheers Luke we have now changed plugs and injectors but still not running but we think it could possibly be timing out as the cam belt has never been changed

[Luke4efc]

It's definitely worth changing the cambelt and probably water pump. I did mine last year and is a really easy job (the pump is a difficult to get in and out though). If I remember correctly the timing can be checked without removing the crank pulley by just removing the wheel and looking through the wheel arch liner. You'd have had the timing cover for the cams off when you changed the plugs so should be easy enough for you to check.

[Luke4efc]

I've just noticed you said it's running 350hp? If so then I hope you didn't replace the injectors with standard ST ones. You'll need 440cc or maybe even 550cc injectors for that power. Have you definitely installed the correct ones?

I'd imagine you're also on hybrid turbo at that power too? Definitely worth checking you're block modded and haven't cracked a liner. Are you losing coolant?

I'd imagine you're running an induction kit too? They're known for killing map/maf sensors which will cause a lumpy idle.