stevieb wrote:
That all makes sense. I've been to the local Pug stealer (less than two minutes walk from home) and ordered a couple more inlet manifold gaskets. They due in on Wednesday, by which time I plan on having a set of six nice new plugs to install. I quite like these Denso ones, and might go for some of their newer equivalents.
These look an interesting alternative to the traditional dual electrode approach -
http://www.eurocarparts.com/ecp/c/Peuge ... 356&000301" onclick="window.open(this.href);return false; - and a good price too.
I can't really tell from the page you linked what it is you're referring to with those plugs - do you mean the fact that it has a dimple on the earth leg as well as the centre electrode ? I'm not sure that I see how that gives equivalent life to a dual electrode plug ? Unless the tips are special material.
Another reason I like the dual electrode design (or the multi-electrode types that have 3 or more spikes coming in from the sides to the centre) is that the spark gap faces directly towards the cylinder leaving the spark more exposed, compared to a single earth electrode which tends to shield the spark from the main part of the cylinder. I've always felt that would lead to better ignition of the mixture, although I don't have any real proof of that.
Whichever plug you go for make sure its the right heat range - I've noticed that many of the automated spark plug lookup based on engine type pages on websites return the wrong heat range (one range colder) than specified by PSA for this engine. (Should be a Bosch heat range 8, a lot specify 7) I have seen only one old Citroen document on the engine that lists FR7KDC but all the later ones specify FR8KDC - perhaps PSA revised the spark plug spec to a slightly hotter plug early on in the life of the engine due to fouling problems in cold weather/short runs ?
I certainly had terrible fouling problems with the colder plugs in mine (see the pics - both types of plugs had done 1000 miles of the same type of driving) so I will be sticking to the correct heat range from now on. If you're buying a different brand plug you'll need to use a lookup table to convert the heat ranges into equivalent numbers. (NGK uses a backwards numbering for example)
Another factor is resister vs non-resistor. Original spec (for both Bosch and Elysium plugs) is a resistor type, the FR7DC+ I had trouble with are non-resistor while the FR8KDC are resistor types - maybe significant as well.
I think the rear injectors are working in the most inclement part of the engine - that inlet manifold must hold an awful lot of extra heat in there. You could think that the front ones would be prone to it too, but I can't help but think those "scoops" in the plastic engine cover help the airflow around the front ones a bit. The rear ones don't have any airflow. I also noticed on mine that the plugs for the rear injectors had full rubber boots unlike the fronts which are regular, exposed, plugs. These rubber boots have scorch-marks on them and look like they'll be turning brittle very soon.
From what I've read varnish forms on the pintle valves when the fuel sitting statically in the injector bakes in the heat after the car is turned off. So it would make sense that rear injectors would be more likely to stick, although again that's only supposition.
As for getting the injectors out of the rails, it's not too difficult.
To completely remove both rails from the car, do you have to disconnect the two rails from each other, or can they be lifted out together ? Apart from the breather hose you broke (must remember to make sure I have heat shrink on hand!) does anything else foul it or get in the way ?
The comment on cheap 95 octane fuel is interesting. Do you mean you used supermarket fuel, or just "cheap" when in context with high octane fuel? I ask because my previous 406 was the lovely 8-valve 2.0 litre petrol turbo (my favourite Peugeot engine, despite similar sensor issues - it was fab
), and it HATED supermarket fuel with a passion. I only used it twice out of necessity (I'd learnt the difference between supermarket and local Shell garage fuel many moons ago when I anally measured the tank-to-tank mpg of my first car - a 1.3 309). One occasion sticks in my mind when I put a tankful of Sainsbury's
high octane stuff in at Swadlincote in Derbyshire. My drive home from there was 20% of mixed 30mph villages and 60mph country roads, followed by 80% of 70mph motorway spec road, and you could physically feel the car getting weaker and weaker. I seriously started to wonder where my RAC card was, it got so bad. I had the full-on "rubber throttle". The car got me home with a bigger drop in fuel than I was used to, and carried on running like cack for a few days until I filled up at the Shell near home. Instantly, with regular Shell fuel, it returned to normal. I don't know what it is about supermarket fuel, but it just isn't as good as the stuff from mainstream forecourts. And I think if it's causing these power and economy issues then what other problems might it be causing? I have little doubt my stuck injector is related to my car being two and a half years old before it left the forecourt - sitting there with a litre of cheap petrol going stale in its tank - and I wonder if the use of this cheaper petrol on a regular basis can have a similar effect over time. In my case, if the previous owner added to an existing problem with supermarket 95RON fuel, it's hardly surprising they've all finally come home to roost...
Yes I'm embarrassed to admit but I was running it on 95 RON Asda fuel for the first 6 months I had it.
My two excuses are one that we were quite hard up at the time, and the other is that supermarkets don't sell fuel in New Zealand so I have no prior experience of buying supermarket fuel.
(This is the first car I've owned in the UK)
So I guess I just didn't realise what poor quality it is. I haven't used any supermarket fuel in the car for over a year though, its been all either BP (both standard and Ultimate) or more recently it has only had Shell V-Power except for one spell when the local Shell were out of V-Power for a week (??!) when I used BP Ultimate again.
In hindsight whilst the car ran perfectly on the Asda fuel while I was using it, it could have been clogging the injectors, also only a month before the performance problems started I had done a big 800 mile trip around the top of Scotland and had been forced to buy fuel from all kinds of small out of the way petrol stations whose names I've never heard of before.. again, the car ran beautifully on that trip but who knows what dirt and gunk could have got into the tank only to be released when it ran low.
It was literally about 6-8 weeks after that trip that everything started to go down the drain...
In fact if this gearbox ever fails on me and I decide to salvage the car, I'm seriously considering doing a manual conversion instead of getting the gearbox rebuilt or replaced...might as well get something good out of something breaking! (V6 manual Xantia's in the UK can be counted on one hand as they were never released in RHD form so it would make it a rather unique and even more fun to drive car)
