V6 fuel filter change

[elma]

I would imagine I did get it wet, things got a little splashy doing the coolant. It got well heated up on a good drive afterwards but I think I wasn't careful enough. Hadn't thought of leads but they and a cassette are now on the shopping list.

[CitroJim]

Hadn't thought of leads but they and a cassette are now on the shopping list.

Notwithstanding Simon's experiences in the matter I've not experienced difficulty with the leads or cassette James and I'd only order a replacement if you can see any physical damage to the leads themselves, clear damage to the cassette or if any of the leads read open-circuit when checked with a multi-meter on the low ohms range...

I've occasionally seen a lead appear open-circuit but a clean-up of its terminals has restored normality...

[Mandrake]

Mine definitely had an intermittent break in the cable where it goes around the tight bend at the back just below the curved guide. They are normally 6k ohm but would go open circuit when bending the wire in that area.

The problem is that the design of the cable run and intake manifold makes that cable area quite vulnerable to damage when the manifold comes off to replace the rear bank spark plugs. You have to be quite careful to avoid undue mechanical stress on the cables when removing and refitting the air intake manifold. So a mechanic who is a bit too enthusiastic and careless could easily cause damage there. Another spot of concern is the small teeth in the guides that hold the spark plug leads - they are very sharp and the cable is a tight fit in them so if you have the leads in and out a few times there is a risk of damaging the sheathing of the cable by puncturing the rubber - happened to me with a new set of leads.

Internal breaks in the wire and holes in the insulation don't necessarily (and typically don't) cause a complete failure of ignition in that cylinder as the spark will jump the gap inside the wire, however it reduces the spark voltage such that it might be OK at idle and light throttle but will misfire under a heavy load either due to low voltage (internal break in the cable) or sparking outside the cylinder. (hole in the insulation allowing the higher spark voltage under open throttle conditions to jump outside to the engine body instead of at the spark plug electrodes)

With an un-diagnosed misfire on a 20 year old car one of the first things that should be eliminated is plug leads IMHO.

I would add that it's good practice to replace 20 year old spark plug leads, on any car - with heat and oil exposure over that period of time most spark plug leads are past their best by that age, even if they have "easy" routing that doesn't place mechanical stress on the cable. The cable routing of the plug leads on this engine is quite poorly designed as the leads are too short and pulled very tight around sharp bends and will be bent sharply when removing the intake manifold.

I haven't had a coil pack completely fail on me yet, but I have had a weak coil pack on both cars that tended to misfire under load - probably due to insufficient voltage output. Although the OEM is Sagem, on this V6 I replaced it with a much cheaper NGK coil pack and I've had no complaints at all - if anything I would say the NGK coil pack is a bit better constructed than the Sagem which I fitted to the old V6.

Troubleshooting ignition problems on this engine is very difficult to do scientifically due to the physical design because you can't do a cylinder drop test (unplug an individual coil or spark plug lead) to identify a misfiring cylinder, nor can you remove or swap individual spark plug leads like you could in the days of yore, or swap coils like you can on the ES9J4S. Swapping spark plugs is also too difficult for a test due to the location of the rear bank. You can only really do so by a process of elimination, which means new plugs and new plug wires to rule that out then maybe consider a coil pack if the problem persists.

In the 2 1/2 years I've had this V6 I've replaced the spark plugs and spark plug cassette together, then later the coil pack, and most recently the TPS. At each step of the way the performance and consistency improved until it has now reached a point where I believe it is performing as it should be. When I first bought the car and drove it back from Steve's the performance was very flat indeed. It's now going like an absolute rocket.

[CitroJim]

Simon, your latest post has jogged my memory of something I may have imagined... Did you once report you could on occasions see corona discharge around the leads where they bend tightly at the back of the manifold or was I dreaming that?

I do recall your pictures of physical damage on the leads where that clip tightly into the carrier...

[Mandrake]

Might have been David Hallworth who mentioned corona discharge now thinking about it Simon...

I always try to push it to one side otherwise its very easy for it to be crushed by the pointy flute in the cover! Even with the extra protective plastic sheath the wire seems to get crushed and kinked here - not a good design!

No indeed, and similar applies to the TCT engine lead guide... it's easy to pierce the insulation on the guide clips if you're not careful...

[CitroJim]

Simon, I do apologise I'm afraid I edited rather than quoted your last post during a very senior moment just then... I was distracted at just the wrong time...

That's why the post above this one seeks top not make any sense...

I hope you can make it good again...

Sorry