I was browsing the internet today looking for clues for the intermittent performance/misfire issue, (as you do

) and came across this old Aussiefrogs thread:
http://www.aussiefrogs.com/forum/peugeo ... sfire.html" onclick="window.open(this.href);return false;
There's quite a bit of misinformed speculation mixed in with the discussion ("try swapping over two of the coil packs", yeah, like you can do that on an ES9J4 with a moulded 3 coil pack

) but here are a few interesting bits snipped out.
The original poster, after just filling up with petrol:
68 404 wrote:After about 40 kms it started missing, especially just off idle. It felt like it was running oin 5 cylinders or something. There is still some sort of hesitation and there is a definite miss at idle every 5 secs or so.
pokinacha wrote:Mines does something very similar.
when warm, above 90C, it will missfire randomly up to 4000rpm. mainly around 2000-3000 but somtimes lower. I've never had it at idle, and above 4000rpm it seems fine. mine has a better flow exhaust so i can hear the missfiring better. sounds like overrun crackle.
i have been told it's a coil issue. just haven't done anything about it yet.
These symptoms of pokinacha's sound very similar to what I had for a long time - no misfire at idle, running perfectly above about 3500-4000 but hesitation and lack of performance below 3500. It's now misfiring at idle as well, like the original poster in that thread. I also notice that power "jumps" suddenly up at 3500 rpm when accelerating... Continuing:
68 404 wrote:It's getting worse!
No problem when cold, it seems to manifest itself when the underbonnet temperature gets hot.
The miss is very present at idle and when throttle is initially applied (like accelerating away from lights). There is an obvious multiple miss under these conditions and then it might clear its throat and accelerate away.
68 404 wrote:Car had full service about 10,000 kms ago (plugs were changed).
And finally the resolution:
68 404 wrote:The 406 is back!
It was the crankcase breather that was the problem. It was full of gunk, perished to a large degree, and totally blocked. The blow by from the engine caused oil to pass beyond the gasket of the crankcase vent, run down towards the plugs causing the misfire!
The coil pack was cracked but is still serviceable. Despite his best efforts, my mechanic couldn't find anyone who would supply a non genuine coil pack...
So can anyone tell me whether the crankcase breather scenario is plausible or not, (or whether his mechanic was spinning him a line) and if so exactly which pipe is being referred to, as there are multiple breather pipes running about the engine...
One thing that does agree with the above scenario is that when I changed the spark plugs a few months ago (detailed earlier in this thread) the front bank were ok but the rear bank plugs were badly fouled to the point that the plugs were causing a misfire even though they were new plugs just a couple of thousand miles and a few months before they came out fouled.
According to someone earlier in the thread (xantia_v6 ? sorry I can't remember) the crankcase breather fumes that go into the bottom of the throttle body are directed to only the rear cylinders not the front...
Again I doubt this is all the issue with this car otherwise the performance would have been normal when I recently changed the plugs - at least for a while, and while there was a big improvement it still wasn't running right, however its possible that those rear plugs are beginning to foul again now, if so I need to find why.
Just a thought...
