I am looking for help trying to diagnose this (i've posted before but have a bit more info)
When accelerating hard (most noticeable in 3rd around 3-4k revs) there is a massive misfire, not even a flatspot, definitely a misfire. The spanner light comes on in most instances, but in some cases, does not.Restarting the engine always clears the fault. Other than this, the car drives fine.At 70mph on the motorway etc,etc.
Car is at 66k miles now.Approx 1 year ago, I had an engine failure and it was replaced by Vauxhall.It was something to do with the chain.Just before this, I had a High Pressure Fuel pump fail.This was also done by Vauxhall under Warranty. I am reluctant to believe it is the HPFP as the symptoms are nothing like what I experienced at the previous failure. In the last week, I have taken out the spark plugs and refitted the old ones (I found one of the plugs to be of a slightly different colour to the others - looks a bit like slight overheating?),did oil and filter and added X1, changed the air filter and let my fuel tank run down and refilled with Shell and added Redex (usually use Morrisons or Tesco as these are my local filling stations).All of this hasn't helped. I appreciate that I may need to bite the bullet and get it Tech 2'd but I just hate the thought of them taking £80 to say - it could be this or it could be that.
From reading this Forum (as I do regularly) it could potentially be the HPFP (but that would really p*** me off after only having this done recently), coil pack ?, dirty injector, EGR ? (not sure what the symptoms would be for this).
Sorry for the speel, just trying to narrow things down