Bad misfire, help needed!

[GTI_Kyle]

Need some help with a bad misfire on my stg2+ FL Leon cupra has developed. It starts ok but sounds really rough with a constant misfire, almost like a Scooby sound. It's in limp mode aswel with the EML flashing sometimes, plugged it in with my basic scanner & it come up as a misfire on cylinder 4 P0304 code.

Changed coilpacks & spark plugs but still same. I suspect maybe a bad injector or bent valves?

Anyone else had this problem?

[Dan_FR]

Very common, will be a duff injector..... Get someone with VCDS to look at the misfire to check its only that cylinder and that its a regual idle misfire that will probably clear up once revved..

Once confirmed, get it sorted ASAP and don't drive it about hard at all, as its a potential engine killer

[GTI_Kyle]

I had to limp it home but barely went over 25/30mph due to being so down on power. Hopefully it is just an injector and not bent valves!

Is there any particular reason why injectors give up?

[Dan_FR]

Common issue on the K04 engine cars....  Could just be carbon build up - ideally all 4 need to be tested and balanced.... R-tech offer this, whether you just send them your injectors or book in to have it all done for you

[GTI_Kyle]

I've had the inlet cleaned & RFD fitted recently mate so won't be carbon build up. Might consider sending them off once the problems diagnosed.

Is there any differences in symptoms with a bad injector & a bent valve?

[GTI_Kyle]

Update - compression test done & there is no compression on cylinder 4. Other cylinders are fine.

Once the heads off will have a better idea what the problem is...