EPC light when going fast

[Graxxel]

hey guys.. I'm battling on with my biggest nightmare job yet.

My leon Cupra 280 runs perfect in almost every way. However on a motorway or anywhere with enough space to really open it out, Once the engine is under all it's load at 95+ throttle, I get an EPC light come on and then then it drops a cylinder. it appears to be worse in cupra mode.

If I back off straight away the epc light stays on until the car is turned off and back on.

If I continue to hammer the car while it's miss firing it would permanently drop that cylinder until the car is restarted. (I am assuming this is limp mode).

I changed the plugs and coil packs. My scan tool doesn't show me a code for the EPC light.

once the car has been restarted you would never know there was a problem... Until you really let it rip in some open space.

I can't find any kind of pattern for when it happens. Such as temperature or whatever. it is just when the car is under maximum load it wide open throttle...

If anyone has any real advice or has delbt with this before, You're help is greatly appreciated.. I just want my Cupra back

 

[Legojon]

Does your scan tool show you misfire count? I'd start with misfire count to see if its maybe an injector, look at fuel requested vs actual see if its a fuel pump problem. MAF, diverter valve - although I don't recall those bringing on the EPC light.

 

[Graxxel]

Hi bud, thanks for the reply. unfortunately it the missfire count doesn't seem to work for the newer VAG cars. I've mostly driven Nissans and stuff before so my scanner worked great for them. doesn't get along with vags so well :/ do you think this is basically not worth even looking into until I have had the car out on a worthy diagnostic?

 

[Legojon]

Yeah, I think it might be better hooking it up to a VAG specific scan tool first. Otherwise you'd just be throwing money at good parts. I've also noticed that there's often discrepencies between tools (eg, some pick up codes others don't and vice versa).

 

[raflo83]

I have similar problem, but....on stage 3. The reason are misfires. It cuts off cylinder at high revs with WOT. Coils, sprak plugs, pcv replaced. Injectors removed and cleaned. Quite a lot of carbon build up in intake - cleaned. Autotech Fuel pump insert installed. No matter If I have stock map or st3 i can see random misfire on all cylinders, but on stock I can’t feel anything and car runs perfect while on stg3 misfires are more frequent what cause at agressive acceleration cylinder disabling after gear change. It might be due to the incorrect map, but even on stock misfires exist. My feeling is that If i do not solve misfire on stock map i will not get proper st3. Who experience misfires on stock? I’m checking it using misfire counter on vcds. What else can cause misfire in this engine and how to check it?