Part two: C5 2.0i 16v

[deian9]

I have some news about my car and it's just by chance that I'm working it all out by fiddling.

I've noticed air intake issues, if I connect the airbox to the bottom bit which subsequently leads to another pipe which disappears into the wing, it suffers from asthma. Where does that pipe go? It seems like theres some plastic inside it, is that normal or is that a blockage? Hence the beginning of badness.

The engine gets lumpy until the evaporative valve starts working. The little brown thing that ticks away when it works. When that doesn't work the engine gets lumpy and there's a hissy gust in the throttle body then it fights to idle smoothy, it's as if it's either running on less cylinders or it's running too rich, which subsequently messes stuff up and the viscious cycle continues in some way.

What I'd like to ask is, does anyone have a diagram of the intake, breathing, vacuum and charcoal cannister system for my car. I'll take a guess and assume the Anti-pollution fault is because the evap valve is blocked in some way for some reason, and it can't take fumes from the fuel tank to add something into the intake manifold to burn cleaner.

How likely is the actual valve to be faulty (it seems to work fine when it does), unless it's a matter of blocked pipes or something disconnected somewhere. How does one get the pipes off the top/bottom of the the evap valve? they seem tightly bonded. Where is the charcoal cannister, is this something that needs renewing?

Onto oxygen sensors, first one seems to be operating at 0.97 V. The second one doesn't seem to do much, it uses about 0.005 to 0.020 V at most, but I haven't done any hot testing after reving, and it is a bit loose in the pipe (because for a weird reason the engine runs less lumpy less often with a bit of breathing space there), maybe I should tighten it up and it'll work better (as in warm up and sense bad gasses).

So basically, any diagrams, or further explanations would be great. I think I'm onto it. Still not sure what the misfire is about, that could be a totally different issue. Or it may fix itelf when I sort this rubbish breathing system. Funnily enough, the car has past receipts for a new fuel tank, fuel pump and throttle body, but not all together.

[Hell Razor5543]

That pipe lead up into the nearside wing, where it ends (open ended, IIRC) to take the air in. If something has blocked it (it is not unknown for it to collapse) the engine can be starved of air. You can (with care) remove the front mudguard to gain access to that pipe.

I had, for a while, an occasional issue with the EGR valve on my C5. It turned out that the rubber pipe that goes from the EGR valve (which was vacuum managed) to the metal pipe on the bulkhead (which then completes the journey in the nearside area of the engine bay) had a tiny hole about 10mm from one end. As the pipe had enough length my friend (who had experience, and found that hole) trimmed the pipe back, and the EGR valve has behaved itself ever since.

[deian9]

I'll definitely look more closely at that tomorrow too. Have you or anyone got any ideas on what the metallic braided pipe is that comes out of the front of the head and into the inner side of the intake manifold? Bit of an overkill if its a vacuum/air pipe, but I must ask.

[deian9]

I've finally worked it out. I believe that I really have this time. I'll give it a few days before I explain it incase it's another theory based on some flawed logic again.

For the record it's nothing to do with the evap purge valve. Well not directly.

[deian9]

There is some kind of short coming from the alternator that makes the sensing wires give a +ve voltage even when off (key out). I believe this is caused by the LDS oil misting from the pipes into it. This in turn causes that connector of blue sensor coming off the power steering pump pipe show a +2.35V? This cannot be right? It's also makes some other sensors show a +ve on one pin, one was the MAP sensor, it was showing a +0.8V (again with everything off).

How does that hydraulic pressure sensor affect the ECU? I can only imagine it corrects the fueling/idle when the steering is used under load, hence the richness at idle? More to the point, how does taking out the sensing wires off the alternator make the +Ve on these sensors drop to 0V?

I only know this because when I cleaned the alternator with a carb cleaner it works lovely. There's still a misfire for some reason from time to time though.

Can anyone confirm or explain what is going?

[deian9]

I give up with this car to be honest. I have it sitting in a friends house, and when it starts,it runs so rich it soon starts spewing out toxic smoke (remember this is a petrol). I had it running ok for a small while, but the fuel economy was in the high teens 19mpg!? Something is amiss, and I cannot for the life of me find where it is, or whether it's a dodgy sensor, dodgy wiring, or dodgy ECU. It has at times run fine, it's misfired and overfuelled due to an injector, so I don't know if it's getting a dodgy signal, or if the injector itself is dodgy, it's had some forte injector cleaner and it ran better, but still heavy on the fuel, and then I drove it back to my friends and now it drowns itself in fuel. So unless someone has some quick suggestions it's going to be scrapped, and I'll get a Xantia diesel instead. Alternitavely if someone wants to make me an offer for it, it's worth it for the parts, but I can't be bothered with it tbh.

[ekjdm14]

Just a thought, I may be putting 2 and 2 together and coming up with 5 BUT.... You mention it's done some misfiring and rough running due to dodgy injector and has spewed fumes from running stupidly rich. Also you mention it seems to help if you leave an O2 sensor loose.

My thinking is maybe it's killed the cat and that's shattered, migrated down the exhaust and is causing an intermittent blockage further back.

Or even just collapsing baffles in a silencer box.

Before condemning the car completely, I would have the exhaust down and check the cat isn't melted/smashed/blocked. Assuming the system is breathing freely as far as the end of the cat then I'd go all antisocial and take the car for a run with the cat back exhaust removed (all sensors plugged in again) and see how it behaves then.

Failing that, how much of an offer are you after & does it have any MoT remaining to get it to Congleton?

[deian9]

It has an MOT until June 23rd. It also has a prang on the offside back light, metal pushed in a bit, but all still works.

As for the running, when it runs well (correct lamda ratio), it's absolutely spot on, returns good mpg, accelerates well and feels planted. But maybe you are right about the baffles in the backbox or the cat being blocked, although tapping the cat with a mallet doesn't give the sound of anything being lose inside.

Over all it's a nice car, clean inside, decent leathers, engine is solid and gearbox works fine (when it knows what the engine is doing). Cleans up nicely.

Looking for £250, it's not worth scrapping if someone has a drive/garage and some time on their hands. It's based in Liverpool if you want a look. But by some weird wiggle of a connection it may even drive again for a while. It might just need a battery? But unless it starts and works fine today and carries on working to pass it's MOT I won't be keeping it.

[ekjdm14]

Cool, do drop the exhaust off behind the cat if possible though and see if that magically "repairs" things... New exhaust would be a lot nicer than new car lol.

If you do end up selling it'd likely be toward the end of the MoT by the time I've sweetened the better half up enough but that sounds a fair price even if we were forced to break it. Saying that I see no reason why a bit of fiddling couldn't see it sorted by your fair hands, and further no reason someone else wouldn't pay that before I'd be able to... Will let you know if/when though if it's still around.

For how long it'd take to drop the exhaust it's got to be worth a shot even if the cat doesn't rattle (Our XM one didn't, and that was because the whole lot had gone down to the silencer!)

[deian9]

I'll have a fiddle today, will drop the exhaust if the ground dries up OK. Until your time comes I'll keep trying with it. Tbh, the insurance is going through the roof because of the slightest prang I had with the car before. So I'm looking to either get rid of it for someone to fix or break it, or swap for a "simpler" 5 door 206ish size car (SW if poss).