207 keeps fouling the plugs

[Frog1]

Hello all. I wonder if anyone can think why a 2007 207 1.4 VTi would keep fouling its plugs and resulting in misfires, cylinder shut offs and no starts.

Background.
Car has only 25k miles from new. Owned for 10+years. Used weekly, doesn't go very far.

The problem started around a year ago, when the car was running rough. Probably on 3 cylinders. Then it wouldn't start. We pulled the plugs and they smelt of fuel, as did the exhaust when cranking.
The plugs were replaced and the car started fine.
Roll on a few months and the same thing again, cleaned the plugs up with wire brush, a drop of oil in the cylinders and it started up ok.
This pattern has repeated itself since, the plugs were changed again from the almost new Bosh items back to Peugeot genuine plugs but no difference. Coils have been swapped around but the fault doesn't follow any particular coil, or plug, or cylinder.

I have Diagbox and other than misfire codes relating to the rough running, I can't see any other codes that return. Where do I go next? Thanks

[ozvtr]

Look (listen) for vacuum leaks. Particularly where the inlet manifold bolts to the head.
Try disconnecting the MAP sensor on the inlet plenum. Try disconnecting the upstream (green) oxy sensor. Disconnecting these sensors (one at a time) should force the engine ECU into a "fail safe" mode. Where it just refers to tables instead of the sensors. If the engine runs better then that sensor is bad.

[xantia_v6]

Check the fuel trims in diagbox live data, to see if they are even and not near a limit.

Possibly a leaky injector or faulty fuel pressure regulator.

[PaulC5]

How far are the trips you are making ? If only short then the car may not be getting hot enough for the fuel mixture to get to a lean one and could be running rich for most of the time.

What are the fault codes ?

Before modern electrics on cars, plugs becoming fouled with carbon (not oil) could be a sign of things including the carb being set too rich, low compression, blocked air filter, not getting up to temperature (faulty thermostat, short trips).

[wurlycorner]

Look (listen) for vacuum leaks. Particularly where the inlet manifold bolts to the head.

Another way to test for this is to spray brake cleaner al around the inlet system methodically. If engine revs increase at any point, you have a vacuum leak in that area. (Be careful not to spray it on the exhaust etc so preferably do it with engine cold).

Do the misfire codes narrow it down to a particular cylinder or set of cylinders?

Can you screenshot the key live data engine sensor readings in diagbox for us when it’s running (and running rough)? (Mass Air Flow, Intake Air Temp, Coolant Temp, fuel trims etc)?

[Frog1]

Look (listen) for vacuum leaks. Particularly where the inlet manifold bolts to the head.
Try disconnecting the MAP sensor on the inlet plenum. Try disconnecting the upstream (green) oxy sensor. Disconnecting these sensors (one at a time) should force the engine ECU into a "fail safe" mode. Where it just refers to tables instead of the sensors. If the engine runs better then that sensor is bad.

Thanks.
There were no obvious vacuum leaks but I will pay more attention to the area you mention and confirm this.
When the plugs are clean, the car seemingly runs good. Hopefully there is somewhere in Diagbox that I can see it running poorly and disconnect the sensors as you suggest.

[Frog1]

Check the fuel trims in diagbox live data, to see if they are even and not near a limit.

Possibly a leaky injector or faulty fuel pressure regulator.

Thanks.
I have looked in Diagbox for fuel trims but couldn't find them anywhere. I am using V7xxx
I did see a 'richness control' but there was only 1 value not a long and short term and it was very close to 1.

Can you point me to how Diagbox can show the fuel trims please.

[Frog1]

How far are the trips you are making ? If only short then the car may not be getting hot enough for the fuel mixture to get to a lean one and could be running rich for most of the time.

What are the fault codes ?

Before modern electrics on cars, plugs becoming fouled with carbon (not oil) could be a sign of things including the carb being set too rich, low compression, blocked air filter, not getting up to temperature (faulty thermostat, short trips).

Thanks.
The trips, whilst short, are often long enough to fully warm the coolant. Also the car has been doing roughly the same since new and only taken umbrage recently.

Fault codes are only cylinder misfire codes. Six months ago there was a code for running rich but that hasn't returned.

[Frog1]

Look (listen) for vacuum leaks. Particularly where the inlet manifold bolts to the head.

Another way to test for this is to spray brake cleaner al around the inlet system methodically. If engine revs increase at any point, you have a vacuum leak in that area. (Be careful not to spray it on the exhaust etc so preferably do it with engine cold).

Do the misfire codes narrow it down to a particular cylinder or set of cylinders?

Can you screenshot the key live data engine sensor readings in diagbox for us when it’s running (and running rough)? (Mass Air Flow, Intake Air Temp, Coolant Temp, fuel trims etc)?

Thanks.
I will look at vacuum leaks next week.
Misfire codes jump around to different cylinders, never the same one, well sometimes, there's only four.
I suspect the rough running is down to the cylinder misfires and caused by the fouled plugs. Once the plugs are clean, it isn't rough but something must be off as it fouls them up.
After cleaning the plug with the cylinder misfire code, the car ran great again and I looked through Diagbox at the data and I couldn't see anything wrong.
Lambda was very close to 1
I cant find fuel trims in Diagbox 7 I think the name is richness control but the value makes no sense to me.
I will screenshot some of the data from the 'fuel injection and emission control' menu later in the week.

Here is a picture of the fouled plug (now cleaned and the car ran seemingly well after this).

[ozvtr]

Can you point me to how Diagbox can show the fuel trims please.

Select "scan tool" when the option comes up.

[ozvtr]

Lambda was very close to 1

How many wires on the upstream O2 sensor?

[PaulC5]

You say the trips are short but how many miles is this ? Using your code reader, what is the engine temperature when it is warmed up - just to check the thermostat is working so should be around 90 to 96°C ?

What is the gap on the plugs, ought to be around 0.9mm ?

I could be wrong, but the fouling on the plug looks like oil - if so is the car using oil, is there any oil in the inlet ducting which could be from the engine breathing ? Cleaning the throttle plate area might help if it is fouled up. With a plug out, when you look in the cylinder does the piston look fouled up or clean ?

[Frog1]

Can you point me to how Diagbox can show the fuel trims please.

Select "scan tool" when the option comes up.

Thanks, we've been looking for this for ages.

[Frog1]

Lambda was very close to 1

How many wires on the upstream O2 sensor?

I'm pretty sure it's a wideband three wire O2 although I will have to check. The engine is a Prince EP3 VTi.

[Frog1]

You say the trips are short but how many miles is this ? Using your code reader, what is the engine temperature when it is warmed up - just to check the thermostat is working so should be around 90 to 96°C ?

What is the gap on the plugs, ought to be around 0.9mm ?

I could be wrong, but the fouling on the plug looks like oil - if so is the car using oil, is there any oil in the inlet ducting which could be from the engine breathing ? Cleaning the throttle plate area might help if it is fouled up. With a plug out, when you look in the cylinder does the piston look fouled up or clean ?

Some trips are less than 5 miles each way. Some are going to be 10 miles. For a small city car, it's probably normal.

The gap on the first Bosch set was 1mm, the genuine Peugeot Beru replacements were 0.9mm.

It doesn't use much oil but the mileage is low. We did inspect the CCV membrane and it was like new. I will look for oil in the intake though and at cleaning the throttle body.