Bad misfire, help needed!

[kyleb123]

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?

 

[boggle]

It very likely to be a faulty injector, its a fairly common problem. But get a compression test done to rule out other more serious problems

 

[kyleb123]

Compression test done, no compression on cylinder 4 will this still be a faulty injector?

 

[Speed-FReek]

Compression test done, no compression on cylinder 4 will this still be a faulty injector?

No compression will either be a problem with the valves or the rings on that particular cylinder. Time to take the camshaft cover off and see from tbe top if there is any obvious valve damage, or try to use an endoscope/borescope through the spark plug hole to see from the inside if there is any damage to the valve heads.

 

[kyleb123]

Doesn't sound good that. If there is damaged valves, is the engine still salvageable?

 

[Rusty2k]

Did you get no compression at all or just a low reading? What was the compression like on the other cylinders?

Could be a problem with the valve train, injector (incl. seal), head gasket or bore / ring damage.

Inspect what you can and if nothing looks obviously faulty then get a leak down test done.

 

[Speed-FReek]

Rusty is right. I had a brain seizure earlier and forgot that the TFSI engine in your car utilises direct injection into the cylinders, so yes, a bad sealing injector could cause poor compression on the TFSI engines. Just do as Rusty recommended.

EDIT: Illustration added (injector is on the left)...

 

[kyleb123]

Had the car sorted, it was bent valves after all cars running good now after a quite hefty bill. However it's seemed to have developed a new problem, sometimes when dipping the clutch the revs take a while to drop, my cruise control has also stopped working?

Clutch switch gone bad I presume?

 

[mty12345]

Clutch switch gone bad I presume?

Definitely sounds like it

 

[kyleb123]

Anyone know where the clutch switch is located?

 

[Rusty2k]

Here you go:

http://workshop-manuals.com/seat/le...tch_pedal_switchf36__removing_and_installing/


Do you know how the valves got bent?

 

[kyleb123]

Here you go:

http://workshop-manuals.com/seat/le...tch_pedal_switchf36__removing_and_installing/


Do you know how the valves got bent?

Thanks mate

My mechanic said it usually happens when your pushing the engine too hard, and over revving etc. I've never redlined it, I have a heavy foot don't get me wrong but never redline my cars. So can only presume it was a previous owner, and it just couldn't take it no more...

 

[kyleb123]

UPDATE: On going issue, replaced the clutch switch & still the same. Random stalling when coming to a stop, sometimes the throttle blips by itself. Also when the car starts from cold there's a slight delay from starting the car to it high idling.

Anyone had these symptoms? Throttle position sensor?

 

[Jfox]

Would it not be worth getting it scanned with VCDS or something?

I know the basic scanners are good (i have one myself) but not all codes come up.

 

[mty12345]

Would it not be worth getting it scanned with VCDS or something?

Yes,+1 on this. VCDS

 

[kyleb123]

Anyone in the west yorkshire area with VCDS? Will repay in beer tokens...