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

[myglaren]

A work colleague has had similar problems with his Toyota. Pump was clogged.

[CitroJim]

The pump looks quite a hefty device from the parts list picture too...

[deian9]

It's about the size of a large fist from looking down at it from above. It doesn't seem too hard to remove.
Blew into one of the pipes, it's full of water, this can't be right?

Thankfully it's dry, but cold today.

Thanks

[GiveMeABreak]

There's not a lot written about it unfortunately, but 6 is the 'Pollution Control Air Intake Valve', 12 is the Air Hose, 13 the Preliminary Filter and 10 is the Electric Relay (35 Amp, Green), but nowhere is anything to do with water mentioned - so I wouldn't expect there to be water in the tubes...

[CitroJim]

Water taken in with the inlet air might have the effect of cooling the combustion a little and thus reduce slightly NOx emissions... A sort of a poor-man's Adblue...

It's what EGR does - reduce the combustion temperature to lower NOx emissions...

[deian9]

Ok, it's off and was full of water. Now I will try to open it and see if it's salvagable. Funny thing is, the alternator now powers a nice steady 14.6V to the battery, with that airpump on it supplied 14.9V at idle and 15V running a little faster. It idles sweetly without it on, so I'll see if it runs better without it on a longer run after it's warmed up, at least where the engine expected the air from this pump is free to not suck water if thats what was happening or it not blocked at least.

It also explains the intermittentness of the problem (water moving about).

I need to see why it became full of water before putting it back on.

[GiveMeABreak]

Sounds like slightly more than simple condensation - that water must be being sucked in from somewhere - give the pipes a good look over in case there is a tiny split - or possible if the car has gone through any deep water and been sucked in that way?

[deian9]

Its still misfiring, but it drives REALLY well on 3 cylinders. Maybe the MAF is water damaged. I haven't been through any water. But when I bought it, it was fine for a good few weeks before it started playing up.

[myglaren]

I would doubt that the MAF would cause a missfire or it to run on 3 cylinders, I imagine a defective injector would be the cause of that.
You could check the MAF visually for corrosion caused by water ingress but be very careful with it, they are surprisingly delicate.

[deian9]

It's coming up with slighlty different fault now, more certain about injector 2, and a camshaft position sensor, this would explain a misfire.

But does it NEED the air pump connected (either electrically or physically plumbed)?

Tomorrow is another day.

[wheeler]

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.

That's exactly what it does, when the engine is started from cold it blows air into the exhaust via a one way valve (no 6 in the pic) to warm the cat up quickly. They normally run for around 1-3 minutes after start up. There should not be any water in there. The pump has no bearing on how the engine runs, its purley for making the cat heat up faster.

[NewcastleFalcon]

Good luck with resolving the problem.
I can't offer any words of advice, just a general observation.
where the phrase "Misfire" or codes p0300, P0302...etc is used in a thread title, I have rarely read a thread where the conclusion is yes it was X and it's now fixed.

More typically it ends up with
I have replaced/cleaned EGR, throttle body, coil pack, sensor x,y,z, and zz, injector(s), inlet manifold and sometimes even the ecu Its been into the main dealers for a week...they can't find anything wrong/can't cure it etc etc

hope this thread proves the exception

Regards Neil

[deian9]

Thanks Neil, One thing I don't do is send it a mechanic. I have an OBD2 reader and I have PaulR close by if I need someone with a Lexia. Other than that it's patience and some methodical diagnosis. It's all too easy to send cars to mechanics for them to charge £40 to plug it onto a computer just to tell you there's a misfire, the real answer is what causes the misfire, and then also what caused that component to fail. Mechanics relish on the idea of getting some labour to install something, I think most aren't trained to understand how cars work, just to plug in a computer see a solution, then follow some instructions off the same system. No intelligence needed.

[CitroJim]

Thanks Neil, One thing I don't do is send it a mechanic.

Indeed, it's pointless in the case of an intermittent issue like this... They can do nothing more than you and the forum can do Dei and actually a lot less. They are time-constrained and charge plenty. Unless they have second-sight, can accurately predict next week's lottery numbers and a crystal ball they'll have no success...

Many have suggested I let the profession have a look at my 207 but again, no point...

In fact two main dealers already have...

keep plugging at it on here and between us all we'll sort you

[deian9]

So today I checked every fuse I could find, checked the circuit board of the fusebox, all seem well.

So I must go back to the faults:
P0202 Injector Circuit / Open Cylinder 2
P0141 O2 Sensor heater circuit (bank 1), Sensor 2.

So from that I conclude that there is a fault in injector 2 (mind that it's injector 1 that doesn't fire when it misfires).
And O2 sensor 2 is faulty (which one is sensor 2, the front or the rear one)?

Going from the wiring diagram an O2 sensor and an injector shares the same earth point and that is the only way they could be related electrically. If that is the case the link is at splice E132A between injector 3 and 4, I peeled all wiring sheathing back and there is nothing untoward going on. Do you think I should open up the splice and see if there is a connection issue inside there? (it seems unlikely).

I checked for a continuity through the earths of all the injectors and both O2 sensors and they all report continuity.
All 4 injectors have a resistance of about 155ohm (or whatever range it was on my multimeter), they all match anyway.

Would the car start and run without an O2 sensor connected (just to isolate it) without damage? If the O2 sensor shorts to earth when it is being switched on by the ECU then could this propogate up to the one injector only, since they share the same earth. Or is the car doing some limping?

What puzzles me is, it's always the injector near the timing belt that doesn't work, yet the fault shows as injector 2?

Another thing I'm thinking about is a vaccum line. There is one that goes to from the throttle body to the master cylinder, I took this off, and it doesn't seal in any way. I could find any tape to seal the ends. My train of thought on this, when the car works on 4 cylinders (or when it was running well when I had it), the brakes juddered as if the ABS was kicking in. (but now it doesn't at all, so I can dismiss warped discs).
Often the brake pedal feels fine (soft), other times not so soft. I know it should build up how hard it is with the engine off and then soften when it starts, but there is no pattern going on here. Once or twice I remember some brake pedalling changing the engine note slightly, but thats a vague memory and I didn't realy think anything of it.

But the weird thing is, it works fine when it's cold, all 4 cylinders and going well. And then it warms up it misfires. If i switch it off afterwards, it will idle on 4 cylinders, then when I give it some load it reverts back to 3 cylinders.
Sometimes it will have a nice few seconds of coming back on 4 cylinders when driving certain routes (usually turning left makes it work a bit better, going uphill and to the right seems to make it go worse). No real correlation to bump or shakes, more left vs right.

I've checked the earth strap to the gearbox housing. It 'seems' ok, a little green but not brittle (sprayed WD40 on it). Checked for same voltage from the + of the battery around parts of the engine bay, engine body, all visible earth points (but not the main earth strap), ecu casing, all showing healthy voltage all over, as in no voltage drop. So I'm stumped there.

One last thing yesterday when I played with plugs randomly (mostly after checking the O2 plugs, the car was fine, (started with the oil cold, water was warm) and I had a good run with it with NO anti-pollution fault, it drove sublime, smooth gear changes, normal braking, power on tap, no engine light for a good ten minute drive, then oil gauge started showing oil warming up (not hot, just warming up to 1/3 way up), then it started misfiring again. It was also the one first time it had warned me that the oil level was getting low on the writting things along with the other faults. Physically it's level is 1/3 up the dipstick or 2 circles in the odometer display). It had never shown me that warning before. One final clue is, there seems to be some oil being sprayed into the air fiilter (through vacuum pipes I guess), it's not soaking, but it needs wiping and has stained the air filter. Seen this on many cars.

I'm assuming it's not a clogged exhaust or catalytic converter since when it runs well it goes really well.
So either some weird ass electrical fault caused by a some weird ass vacuum fault, or both, or neither!? Any new ideas based on the above? Anyone, before I cry lol.

That's it for now. I am very thankful of the continued support.