C3 Picasso - Smoke from exhaust, running rich?

[Pulseammo]

Hello all, you may remember me from other fun threads such as "Is my timing out enough to cause no start?", but I am back once again to terrorise the forum and pick your collective brains.

I'm having some further problems with my C3 Picasso, namely:
- Smoke from the exhaust when pulling away from lights / after idle.
- Not really any smoke when idle or at constant cruising speed. But pressing accelerator after idle causes it, pulling from lights, junctions, etc.
- Yesterday the car started to stall near idle revs (pulled up at lights and stalled by the time I came to a stop, couldn't get her started again).
- When the car did start again (after being pushed into a side street), it wanted to stall unless the accelerator was pressed slightly (1.5k RPM).
- When the car would not start it would crank and make a kind of "whoomp" noise at the end of cranking, sometimes it will make this sound when pushing smoke out, I think it may be misfiring.
- After a couple of minutes holding the throttle at 1.5k I was able to release it without stalling.
- Smoke in my opinion is a brown / grey, maybe a hint of blue though.
- Idle in general doesn't seem rough?

(Photos taken at idle, but after giving the accelerator a quick press to make smoke appear)






From what I can tell the problem gets worse once the engine gets to temperature AND driving around - for instance it can sit idle on the drive without stalling for 10+ minutes.

So far:
- I've replaced the PCV valve in case it was stuck open, no change. (Valve cover gasket also done before.)
- Checked PCV has negative pressure at valve cover, it does. Checked for cracks in PCV hose, don't think there is any.
- I've compression tested the cylinders to try and rule out worn piston rings, 175PSI every cylinder, dry test.
- Air filter hasn't been changed in 3 years but only has 15k on it, looks fine to me.

Questions:
- I've pulled my spark plugs and found that I appear to be running rich, can anyone confirm this is dry carbon deposits near the end of the threads?
- Also looking at this video you can see that there is a lighter portion on each insulator tip, is this bad spray pattern from injectors?









A couple of weeks ago this car wouldn't start because I believe the cylinders got washed with fuel, when I pulled the plugs diagnosing that problem they looked like better than now, no black carbon around the end of the threads (please ignore the oil deposits on these older photos, valve cover gaskets needed done and have now been done). But the smoky exhaust has gotten worse over the last two weeks. I am wondering if a rich condition existed before which caused my cylinder wash out a few weeks back.

So I'm lost as to where to go with this. I've taken some live data, short term fuel trim is 0% at idle (when there is no smoke), but ranges heavily between +/- 20% depending on throttle. I'll see if I can export the graph to a better format.

Anyone know what diagnostics I should be carrying out for all banks apparently running rich?
- Lack of airflow?
- Oxygen Sensors?
- Fuel Pressure Regulator?

Thank you!

[Pulseammo]

Adding some live data:

Removed the exhaust vanos solenoid (because there was a pending P0014 code, but I don't think it's recent, I can't get the codes to clear to see if it returns), clean as a whistle, almost no debris at all on the filter screen - so clearly I'm looking after the ungrateful heap of junk with its oil changes.



Honestly I've never really read live data but this all looks fine to me also, car isn't adding or removing fuel in reaction to the smoking exhaust as far as I can tell. Sensors seem to be reacting normally when I use start spray to create a rich condition.



Completely stumped. I removed the air filter and allowed the car to idle for a bit - no change, so intake filter is clean enough.



I don't feel a huge amount of air rushing into the intake, but covering it with my hand you can feel a suction start to build up. To be honest if I had a restricted intake or a defective throttle I'd be expecting the fuel trim to be subtracting a ton, and it's not.

Unfortunately my scanner doesn't report the MAP sensor.

[ozvtr]

I'm having some further problems with my C3 Picasso, namely:
- Smoke from the exhaust when pulling away from lights / after idle.

Valve stem seals.

Questions:
- I've pulled my spark plugs and found that I appear to be running rich, can anyone confirm this is dry carbon deposits near the end of the threads?

Anyone know what diagnostics I should be carrying out for all banks apparently running rich?

Look at "long term fuel trims". 0 to 5% good, 5 to 10% average, 10 to 25% bad.
Over fueling (rich) probably means a vacuum leak. Could be a bad O2 sensor or MAP sensor or Mass Airflow sensor (I'm not familiar with your engine).

[ozvtr]

Ok, a look at the scans shows everything looks OK.
O2 sensor 1 shows stoichiometric mixture of 14.75, fine.
Short term fuel trim bank 1 averages around 1.5% fine.
Forget O2 sensor 2, that's just the catalytic converter.
Unless the wide band O2 sensor is faulty (I doubt that), I'd say you were burning oil from the valve stem seals and the soot on the plugs is burnt oil!
Engine consuming oil?

[Pulseammo]

Ok, a look at the scans shows everything looks OK.
O2 sensor 1 shows stoichiometric mixture of 14.75, fine.
Short term fuel trim bank 1 averages around 1.5% fine.
Forget O2 sensor 2, that's just the catalytic converter.
Unless the wide band O2 sensor is faulty (I doubt that), I'd say you were burning oil from the valve stem seals and the soot on the plugs is burnt oil!
Engine consuming oil?

Not quite sure on the consuming oil really. It's an EP3 8FS, they all consume oil, but I don't think it was more than usual.

I did some tests for the valve stem seals, going down a long hill engine braking and got no smoke doing that. Also checked for smoke as the ignition key was turned and also nothing there until after the first minute.

That said the car seemed to be getting a little better and I've taken it for 2 test drives now, the smoke has stopped and also no sign of stalling.

This occurred after I:
Took both vanos solenoids off. Exhaust side completely clean, intake side a little dirty on the screen, slightly low resistance reading as well 7.5ohm compared to 8.5ohm but still actuating well on battery test.
Cleaned the throttle, although it was very clean but some oil mist on the backside.
Cleaned out the PCV breather with a vacuum - this was full of sludge actually, so I put brake cleaner down it and vacuumed it out.

Honestly I can't see how any of what I have done would have fixed anything, but there's absolutely no smoke now, it didn't go away immediately after my work, but over a bit of time it went.

So I guess the thread is on hold until the problem comes back (because I reckon something is intermittently faulty).

Throttle:


Intake Manifold end of the PCV hose:




Exhaust Vanos:


Intake Vanos:

[Pulseammo]

I'm having some further problems with my C3 Picasso, namely:
- Smoke from the exhaust when pulling away from lights / after idle.

Valve stem seals.

Questions:
- I've pulled my spark plugs and found that I appear to be running rich, can anyone confirm this is dry carbon deposits near the end of the threads?

Anyone know what diagnostics I should be carrying out for all banks apparently running rich?

Look at "long term fuel trims". 0 to 5% good, 5 to 10% average, 10 to 25% bad.
Over fueling (rich) probably means a vacuum leak. Could be a bad O2 sensor or MAP sensor or Mass Airflow sensor (I'm not familiar with your engine).

Oh! I missed this post!

The long term trims are at 0.8% if memory serves correctly? They are under 1% anyway... I'll check them again at some point.