Was driving home today in the fog and it was around 2 degrees, i floored it to get past a fiesta when the ses and asc light appeared ...then i was in limp home mode 60mph with 255 horses under the lid was pretty sh#t

Anyway pulled over and checked the code got P0300 Random/multiple cylinder misfire, cleared it and restarted .....everything was ok again then floored it to check then all of a sudden the same happened .

So i drive the remaining 40 miles steady with no probs .

Has anyone else had this? ive never had it before and seems to be happening only in cold/dense weather at WOT.

Will check the plugs,leads,wiring out tomorrow...any ideas would be appriciated.

Cheers,Rick.

 

Huh?

 

Huh?

 

When that happened to mine it was the supercharger relief valve. The diaphram was cracked and stuck in the opened position.

Rich

 

Huh?

 

I don't think your Bypass Valve for the supercharger would have caused such things.. You said 2 degrees outside! Thats what the temp was when I broke my Halfshafts in the middle of Wisconsin on my way back to Michigan.

 

Oook.....So you can break metal at that temp but its not gonna damage a piece of rubber?

 

I would consider checking to see if you have moisture in your fuel tank. Going WOT might introduce just enough water into the system to cause a missfire, where "normal" driving keeps the A/F ratio in a burnable range.

If you garage your car you might end up with a wide temp differential that causes water to condence in your tank. Pour in a can of dry-gas and get a full tank fill up at a quality station and see if that helps.

 

Thanks for all the thoughts, i have tested it again since and again can only get it to happen on the motorway but on the openroads its fine

I am wondering if the plugs are rated to cold and all the heavy cold air coming into the engine are causing a misfire?

 

Huh?

 

Check the hose from your intake to your TB. Mine poped out due to por tightening and I got error P0300. Everything has been working fine now.

 

Since the ASC lamp came on at the same time, maybe you broke the tires loose and over-revved it? What RPMs were showing on the tach?
Oh, people, it's 2C, not 2F.
He's in the UK.

 

i have. mine turned out to be my coil pack .

 

Would think moisture in tank or fuel. Fuel quality here has been an issue. Had similair problem which during our cold spell was repeated # time's. Changed fuel brand and resolved the prob.??

 

X 2, X4 & X 7