[sworks]

Originally Posted by mbonwick

The cold running problem did start at the same time the VVC manifold was fitted, but then the ported cylinder head also went on that day too, so can't point the finger definitively anywhere.

I Remember a few of us looking at options at Gretna. The uneven firing pulses through the exhaust at the time suggested cam timing to me, was this rechecked and ok, has that stopped? The oxygen sensor obviously wasn’t working in current data but you’ve now fitted a genuine one. I’ve just seen the mention of the head and manifold being changed at the same time the fault started. Was the ported head your original or a replacement? I’ve seen an issue on the K series where the symptoms were similar to inlet manifold gasket failure but not caused by the gasket. You have a VVC manifold so can discount the gasket. It was a 400 tourer and I found on removing the head there was a very small mark on the head by the fire ring, upon testing it was a hole. Once the car had been parked up overnight the coolant would leak into the cylinder and the car would start with a misfire for a few seconds then clear. There was no indication of wet plugs and this was in the days before borescopes. The head was drilled threaded, a threaded plug fitted and skimmed level and the result was instant. It was my own car so nothing to lose as it potentially needed a new head anywhere and the fix lasted a good 12 months before the car was traded.