207 keeps fouling the plugs

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wurlycorner
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Re: 207 keeps fouling the plugs

Unread post by wurlycorner »

Frog1 wrote: 31 May 2025, 18:51
The values all look to be the same as the reference value. I can't see anything wrong.

Does anyone know what 'filling' is?
I don’t know what ‘filling’ is in reference to tbh, no, or what the % values are. It’s the absolute values (kg/s etc) I was curious about for the MAF - whether they were in the realms of normal/correct or not.
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Frog1
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Joined: 17 May 2025, 19:50
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Re: 207 keeps fouling the plugs

Unread post by Frog1 »

Rp0thejester wrote: 31 May 2025, 20:14 Firstly I would ditch the plugs and replace with 4 points. No need to gap. Secondly, and this is a long shot, check the exhaust gasket is still intact and not leaking. This could stop proper readings getting to sensors and forcing the car to over fuel. Not everything on a car is monitored electronically, this maybe a mechanical issue.
Good shout.
A leaky exhaust would fit the symptoms but I can't see anything wrong in this regard. I also can't hear any exhaust leak and the O2 sensor is in the engine bay so any leak would be pretty noticeable.
The car only has about 25k miles on it too, so the exhaust is good, in the engine bay at least.
Frog1
Posts: 17
Joined: 17 May 2025, 19:50
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Re: 207 keeps fouling the plugs

Unread post by Frog1 »

I really don't want to throw parts at the car without properly diagnosing the issue but we're running out of ideas.

I want to establish if the upstream O2 sensor is faulty.
The car has, on a couple of occasions over the last year, thrown the codes for rich running. P2178 P2192.
It fouls the plugs every month or so.
It smells rich and you can hear the odd pop from the exhaust as well as see a bit of white smoke on occasion.

All the above symptoms were in play during these captures but not necessarily consistent.
207 up rich o2v 23.png
207 up rich o2v 1.png
207 up rich 22.png
207 up rich 11.png
207 up o2v.png

To me, the Lambda (upstream richness) and the Upstream O2 sensor voltage (should be close to 1500mv) are all over the place in most of the captures but not consistently rich, they mostly fluctuate.
I do not have known good graphs with which to compare but I presume the graphs should be flatter. One of the Upstream richness graphs is pretty flat.
Note the graph scale changes.
They were all captured at idle and warm within an hour or two.

Does this upstream, wideband O2 sensor look faulty, given the rich symptoms?