Misfire and stuff on 04 C5 2.0i (not hpi)

[deian9]

Here's an update. So I haven't been able to do any real digging in the engine bay for wiring issues... BUT...
What has happened is, it's better for some reason, and I may be closer to working out why, but it's just a theory.

I think it could be a vacuum problem related to the brakes/suspension.

Now the only reason I think this is because after a miserable run to hills of Yorkshire the other day, I exercised the suspension. And on the way back home it behaved well. Maybe a coincidence?

This morning, it started a again a bit, did some citrobeotics. Braking lifted the back suspension a bit when pulling up to a traffic light on way back home. So when I finally arrived home it did the misfire thing again, so I did citrobeotics again and pushed, settled it, pushed the brake pedal down hard and fast and pulsing it, and you can feel it harder some time, then it's better. All this and the engine changes tone and misfire on and off. Noto much a coincidence now?

I noticed the C5 has traditional brakes, ie master cylinder, separate oil, this vacuum feeds off the engine right. So it's something there. But is it, or how is it relates the suspension beIng exercised?

Thanks.

[CitroJim]

That's interesting Dei... There could be a vacuum leak around the brake servo possibly that is intermittent and lots of braking and so on temporarily cures the leak... The vacuum pipes as well as the servo itself could be the problem...

[deian9]

What is that brown solenoidy kind of thing attached to the inner wing near the master servo? It has a vacuum (or air) pipe pipe going to it from the throttle body. There is also another black vacuum/air pipe going from the throttle body to the master cylinder.

It's interesting really, because with the car working better, the juddery brakes are back (I think I mentioned an ABS-y type judder when braking, but then it doesn't seem to be there all the time, mostly when I don't notice, and come to think of it, it hasn't been there until today, when the car has worked well).

So I wonder if this brown thing links the ABS unit to the master cylinder. Is it some kind of vacuum switch to help the ABS unit know how hard I'm braking? And that it's somehow intermittent because of a permanent but very slight vacuum leak?... hence the ESP/ASR light coming on when it all gets too much for the car. So maybe it's the car going to limp mode, but it never tells me it's in limp mode.

Obviously I can't quite put my finger on the issue, but does anyone think I'm on the right track?

[deian9]

This is fast becoming a journal. ...So no one thinks I'm on the right track because sometimes I do go into one with my theories. So scrap those last few thoughts. Here's an update.

This weekend I got to go under the car in Wales. Found the front suspension subchassis only held on by the two big main bolts and with no additional 4 supporting bolts (2 on each side). No wonder the car danced on it's tip toes when cornering hard (only happened twice) or judders when braking. If I had a crash in it like that the whole front of it would have comeinto the passenger compartment crushing everyone.

What I did notice whilst driving to wales on Friday evening was that the wipers are definately slower when it misfires. I was driving in drizzle with the wipers on the normal setting (not auto or fast), and it they were juddering as the cleander the drizzle, then the car went to firing normally on 4 cylinders and the speed and smoothness of the wipers improved. I think this is a big clue that it IS power problem somewhere (as I thought in the very begining, before I looked into other crazy clues). On top of that, some faults also come up well later into a journey. By that I mean, it feels as if something wakes up after ten minutes and then all the faults come on one after another.

Also whilst underneath I also found the rear O2 sensor also loose, so thats tightened up now. I thought that would fix it, but noooo.
Another also, I started stripping back all the wires of the loom looking for breaks as there are plenty of bends for the wires to break and rub, this resulted in some wires being moved and pushed about (randomly), I then started her up again, and it revv'd to 1500rpm for a bit, switched her off, poked again, bit more normal afterwards. Then I went for a cup of tea and a cry.

So coming back to Liverpool yesterday I think it went into proper limp mode. It had no gears, I was doing 70mph at 4000rpm and the gearbox wasn't locked up into a gear (didn't see any flashing lights on the gear indicator (no snow and sport light on), and no way to manually select a gear. So I pulled up, stopped, and then it was ok... for a few minutes.

So before I strip back all the wires and expose all the elecrics does anyone think this could be related to the battery (which is quite new according to the receipt)? Or does the fact that there are stored faults, indicate there are actual wiring faults that need further investigations first?

I also bought some Cataclean yesterday too in case the catalytic converter is blocked, but upon second thought it does seem to work well and smells of the eggy sulphur when driven hard when cold. So I think chemically it works. When it does work on full power (whether it's real electrical power and all 4 cylinders) I cannot fault the car, it's dream it pulls very hard through out the engine range, but right now I just want to blow the stupid female canine of a car up it's own backside. I was so angry with it on Saturday morning that I took the 'stupid female canine of a car 'for a the most brutal drive it's ever had down the Anglesey backroads (this was before I found the missing chassis bolts!!).

Hate it and love it at the same time. Ideas, advice still welcome.

[CitroJim]

Scary on the missing bolts front!

What I did notice whilst driving to wales on Friday evening was that the wipers are definately slower when it misfires. I was driving in drizzle with the wipers on the normal setting (not auto or fast), and it they were juddering as the cleander the drizzle, then the car went to firing normally on 4 cylinders and the speed and smoothness of the wipers improved. I think this is a big clue

I think it is too

This shouts battery and/or alternator to me or possibly even a bad/intermittent earth...

A slightly dicky battery seems to be the root of a lot of strange faults on these modern cars... It will be worth doing some battery tests and seeing if the battery is good. If it reads under 13.8v just after it's been on charge - say after a trip - then to my mind it's getting a bit past it...

Is the alternator putting out a good, solid 14.4v on charge?

Check the body to engine/gearbox earth strap and the battery to body earth strap - the big meaty ones...

[deian9]

Thanks for the ongoing advice Jim. One question though where is this strap? And it is literally a braided strap right? More than one?
I've had a good dig around the engine bay, from top and bottom and I haven't come across any kind of strap as of yet. Is it literally underneath the engine and gearbox? Maybe I didn't see it because of an undertray (I really can't remember seeing or not seeing one).

One other final bit of info I want to share out aloud is the amount of oil sprayed over the alternator. If oil gets into it's internals would this mess up the capacitor/inductor characteristic of the alternator and overcharge the battery? I am not sure what oil it is, it looks black and engine like but it doesn't use oil (maybe it's LHM/LDS oil from the fabric like braided hoses of the spheres).

Anyway. Each morning I wake up enthusiastic to fix the darned thing, then I get busy and then the sun goes down!
I'll keep looking, but if anyone knows how I can find the strap it would be much appreciated.

Thanks

[CitroJim]

Sorry Dei, when I say a strap is what we used to call them in the old days when often they were just that. Today the 'strap' is a heavy cable.

It should be fairly straightforward to trace the heavy battery negative (earth) cable to the body and then onto the engine and gearbox. Often the earth cable is bolted to the top of the gearbox under a 13mm bolt and big lug...

Oil spraying on an alternator is never a good idea. LHM leaking from the pump onto the alternator on Xantias has been known to kill them. Oil inside an alternator can certainly upset it if it gets onto the brushes and commutator.

[deian9]

Is there anything I can spray onto/into the alternator to clear it of oil without damaging the internals?

[CitroJim]

Is there anything I can spray onto/into the alternator to clear it of oil without damaging the internals?

I've had success by liberally applying electronics grade solvent (such as Electrolube ULS) and blowing it out with a high-pressure airline...

On all occasions I've done this with the alternator on the bench; it would be very hard to do in-situ...

[deian9]

I found a blown 30A fuse... Air Pump. What is the deal with this thing? I assume it's there to help with emission in some way, hence the anti-pollution fauit. I think it's located down underneath the airbox... but 30A!

Maybe a short here is causing the rest of the faults, I'll have a better look tomorrow. Is this a serviceable item if for instance it's seized.

And, this is a bit of a long shot, but does anyone have a diagram of the exhaust and emission system for my car?

Also of note today (with it putting me into third gear, no locking up and misfiring, esp/asr fault, catalytic converter fault, anti-pollution) was the fuses in the car, they seem to have brown gunk on their inner side that can be scratches off with a nail. They look burned, but they aren't brown inside of seem damaged (this was the ecu fuse, fuse 23).

But the air pump being blow seems to give some clues. Any ideas anyone? Going to spend tomorrow looking towards the BSI unit/fusebox for clues.

[CitroJim]

I'm intrigued by this air pump Dei...

The last time I heard of an air pump being used on an engine in connection with emissions was on old Yankee V8 stuff.. It was intended to cause a bit of an 'afterburn' in the exhausts to burn off any left-overs... It was a bit of a fudge at the best of times...

Here's a Wikipedia article about it

[xantia_v6]

Air pumps for emission control disappeared when lambda sensors and closed-loop operation were introduced (about 1975 in the US and about 1990 in Europe). I would be suspicious that the fuse has a misleading description.

[Edit] Apparently they came back...

[Paulmi16]

The air pump sounds like it could be something that help the cat warm up quicker a bit like the VW Supplementary Air Injection system.

I would assume that it only affects the car when running from cold as once the cat is up to temperature its job is done, but if its not functioning properly it could be confusing the ecu.

My experience of these type of systems is on a Golf and removing it made the engine breathe a lot better, it went like a 2.0 should rather than the a strangled 1.6 and other than the anger management light coming on to record a 'low flow' fault, it certainly has been no detriment at all in fact quite the reverse.

[GiveMeABreak]

Deian, can you advise of the fuse location (passenger compartment or engine bay) and fuse number? Are you sure this isn't Air Con Blower? I have your VIN, so I'll look up fuses for you.

Edit: Now likely to be the item below

[GiveMeABreak]

Ok, I think I've got it - the 'Pollution Control Air Pump', listed as part 9 on the following diagram. If this is on the blink, it would certainly contribute to the engine issues!

Part Number: 1618 E4