C5 Mk1 1.8 Petrol - Various

[johnnyj]

Hi folks, I hope you're all well. It has been a little while since I posted in the forum, but here goes...

I still have my C5 Mk1 1.8 petrol and it has been a reliable and comfortable car. However, it does have some faults which I'd like to rectify if possible. What I thought I'd do for starters is list them here and see if anyone can spot any commonality between the symptoms which might lead to some ideas about possible faulty components. When I get a moment I will try to find a garage with Lexia to get a list of any error codes. In the meantime:

1. The car seems to drink a lot of petrol. I am rubbish at maths so haven't tried to do any on this, but it is one of those cars where you can pretty much see the needle going down every journey. The average consumption according to the readout is 7.8 L/100KM which I think is within tolerance, but I am not sure if the car's system for reading this is an actual or "what it thinks it is". I have cleaned the throttle body and butterfly in situ, which were very caked up. That seemed to improve it from its previous 8.6.

2. It is, in my opinion, down on power although not all the time. Sometimes it seems to nip along, other times it is slow up hills and I have to change down. When it is like that, it feels like reduced performance mode (if it has that!).

3. When I start the car from cold, it often over-revs to over 2k at idle. The revs gradually rise to what I see as unhealthy cold engine levels, so I switch it off. When I do that and re-start it, it is fine. The first time it did this I also got an error message that said something like "Anti Pollution Fault". * see 4, below

4. Under certain conditions, I get an oily smell in the cabin. The conditions are (a) when the window is open (no smell when closed) (b) only when on the over-run, say, doing 70KPH downhill on minimal revs. I have changed the cam cover gaskets as they looked leaky and the breather pipe from the cam cover to throttle body, as it was split. * Incidentally, after doing this, I got the problems listed in 3 above.

So, just wondering if anything jumps out as perhaps common to some of these?

many thanks
John

[Harlequin]

30 mpg is about right for a smallish engine in a large body (and alot better than my own V6 petrol, which gets 21 mpg average over a full tank - about 260 miles betwee refills)

Has the car been serviced? Not sure if yours has a fuel filter though

[mickthemaverick]

My thoughts there John make me think of a sticking EGR valve if the engine is fitted with one. When the engine is cold and an EGR sticks open it causes a drop in combustion temperature and so less efficient burning of the fuel. Likewise as the engine warms if the valve does not operate correctly it can severely affect the mixture signals sent to the ECU resulting in wrong adjustment of the mixture. If it does have one I would advocate a good clean and check the pipes for leaks Good luck

[GiveMeABreak]

There's no EGR valve on the petrol C5 engines Mick.

[mickthemaverick]

There's no EGR valve on the petrol C5 engines Mick.

And all the better for that I say Thanks Marc, Back to the drawing board then.

[Clogzz]

There's no EGR valve on the petrol C5 engines Mick.

Mine does somehow and I've disconnected it years ago because it was annoying me.
It always indicates ‘antipollution fault’ but that doesn’t annoy me.
No MOTs here, they just want about 300 GBP per year to keep going.

[GiveMeABreak]

I should of been more specific, the standard 1.8 petrol doesn't, unless it's the EW7J4 and specifically specified with "EGR" + "Pulsair" Air Injection.

[johnnyj]

Hi folks and thanks for the ideas. I am glad it doesn't have an EGR valve.

By way of an update, I replaced the injector seals as they were cheap and I was bored, and that seems to have made a big difference to the car's performance. It also coincides with the "revving its nuts off at switch-on" fault disappearing. The fuel consumption is a steady 8L/100km and perhaps I have to accept that it is what it is.

The hot oily smell remains, but only when the engine is warm, going downhill, on over-run. It does it at exactly the same place in the road on a particular journey I regularly make. If I close the windows it magically goes away. Just wondering if anyone has any thoughts on this last fault? Perhaps oil leaking when the car is at a downward angle and being displaced onto something hot?

Cheers all

John