Technical Combustion problem.

[ccavalles]

Good morning.
I am trying to solve the problem with my Seicento 1.1. The car had a faulty camshaft sensor wire. Sometimes it would stall and not run combustion properly. I have replaced the wire with a new one, but the car is still emitting smoke and soot. It starts on the first try, no problem with that. The injectors were cleaned. Curiously, it didn't pass the vehicle inspection this year because of emissions; I touched the wire and it passed without any problems. I removed the spark plugs and they were dirty with soot. I put them back clean, but it still emits black smoke. Any idea what it could be? I see all the wiring is fine, coils and wiring were also replaced with new ones not long ago. The catalytic converter is also relatively new, as are the sensors.
When running, sometimes it works correctly and other times it seems like it has no power. But it does not stall.

In the video, more black drops than usual can be seen. I have put some cleaner through the exhaust.

 

[ccavalles]

Of course that's not normal.
It is running very rich or possibly spark itself is very weak there or missing completely.
Does that happen on only one cylinder or across all of them?

the 4 cylinders the same.

 

[bugsymike]

Just a thought based on a Nissan Micra years ago, no error codes and often if started up and driven straight away no issues, however at certain times it would run so rich it would kill the engine and plugs soaked with fuel.
The cause was a temperature sensor and it's wiring connection. Apparently a known Nissan fault at the time and a new modified sensor and wiring was the cure.
What it did was sent a false temperature reading to the ECU saying it was much colder so needed more fuel which soon caused the engine to be excessively rich.
Can you get readings of engine temp sensors and compare with real time temps on your diagnostics?

 

[ccavalles]

Just a thought based on a Nissan Micra years ago, no error codes and often if started up and driven straight away no issues, however at certain times it would run so rich it would kill the engine and plugs soaked with fuel.
The cause was a temperature sensor and it's wiring connection. Apparently a known Nissan fault at the time and a new modified sensor and wiring was the cure.
What it did was sent a false temperature reading to the ECU saying it was much colder so needed more fuel which soon caused the engine to be excessively rich.
Can you get readings of engine temp sensors and compare with real time temps on your diagnostics?

Good idea to investigate. It makes sense. Thank you very much for the help.

 

[ccavalles]

 

[bugsymike]

Any chance of a video of the exhaust when revving up at that point?
Any smell of petrol?

 

[ccavalles]

The exhaust video is from the same day. He doesn't always do it. Only when you get going. When stopped, at idle it doesn't go down. Weird gasoline smell from the exhaust. Tomorrow another video to see if it captures when it goes down.

 

[ccavalles]

New video. Today it didn't break down like in the previous video, but that sound and that black smoke aren't normal.

 

[bugsymike]

View attachment 490423
New video. Today it didn't break down like in the previous video, but that sound and that black smoke aren't normal.

Thanks for the video, was this from stone cold or had the engine had a run?
On the video just after half way, some muck came out onto the camera, any idea what that was, is there any water/condensation coming out?
If water comes out as condensation when cold that is normal , but if engine fully warmed up it would need checking.
Sometimes after a run I will put my hand on the exhaust and see if any damp/condensation there.
Engine did sound like it was misfiring as you brought the revs up higher.
The earlier error code P0170 Lambda/O2 sensor on bank one (basically the Lambda sensor nearest the engine on the catalyst, did you get further readings on that as it should send the data back to the ECU so that the Lambda sensor after the Catalyst shout read that the fuel mixture has been corrected.
Incidentally any air leaks on exhaust can affect results or even if Lambda sensor old or new when refitted to the new catalyst if any oil etc. gets on the sensor when fitting it can affect it's readings.
Was the Lambda sensor ever replaced and if so was it a good quality?
Can you get or have you got live data readings of both lambda sensor readings, before and after the catalyst?
You can look online at Lambda sensor readings to see if yours are normal.
Your earlier P0170 :-Trouble code P0170 is an OBD-II generic code that means "Fuel Trim Malfunction (Bank 1)." It triggers when your car's engine control module (ECM) detects that the air-fuel ratio is consistently running too rich or too lean.
This is the reading from the Lambda sensor nearest the engine on the catlyst.

 

[Mike1alike]

This is the reading from the Lambda sensor nearest the engine on the catlyst.

The pre cat sensor.

 

[ccavalles]

Thanks for the video, was this from stone cold or had the engine had a run?
On the video just after half way, some muck came out onto the camera, any idea what that was, is there any water/condensation coming out?
If water comes out as condensation when cold that is normal , but if engine fully warmed up it would need checking.
Sometimes after a run I will put my hand on the exhaust and see if any damp/condensation there.
Engine did sound like it was misfiring as you brought the revs up higher.
The earlier error code P0170 Lambda/O2 sensor on bank one (basically the Lambda sensor nearest the engine on the catalyst, did you get further readings on that as it should send the data back to the ECU so that the Lambda sensor after the Catalyst shout read that the fuel mixture has been corrected.
Incidentally any air leaks on exhaust can affect results or even if Lambda sensor old or new when refitted to the new catalyst if any oil etc. gets on the sensor when fitting it can affect it's readings.
Was the Lambda sensor ever replaced and if so was it a good quality?
Can you get or have you got live data readings of both lambda sensor readings, before and after the catalyst?
You can look online at Lambda sensor readings to see if yours are normal.
Your earlier P0170 :-Trouble code P0170 is an OBD-II generic code that means "Fuel Trim Malfunction (Bank 1)." It triggers when your car's engine control module (ECM) detects that the air-fuel ratio is consistently running too rich or too lean.
This is the reading from the Lambda sensor nearest the engine on the catlyst.

Thanks again for the explanation. The sensors were replaced recently, just a few thousand km ago. The catalytic converter was also replaced a couple of years ago. I'll remove the sensor, it might be dirty because of the crankshaft sensor issue. We'll investigate.
There is smoke with soot coming out of the exhaust. It makes the ground black like it would with diesel.

 

[bugsymike]

Thanks again for the explanation. The sensors were replaced recently, just a few thousand km ago. The catalytic converter was also replaced a couple of years ago. I'll remove the sensor, it might be dirty because of the crankshaft sensor issue. We'll investigate.
There is smoke with soot coming out of the exhaust. It makes the ground black like it would with diesel.

Have you any way of testing the Lambda sensor and was it a good make?

 

[ccavalles]

Have you any way of testing the Lambda sensor and was it a good make?

I don't know. It's been going well for about 3 years or so. I don't know what brand they are. They're not very expensive either. The first thing is to take it out and see if I can clean the carbon buildup. I think the problem might have been the crankshaft sensor that I changed, which caused the spark plugs and sensor to get dirty.

 

[bugsymike]

The one nearest the engine does most of the work , the second one is to tell the ECU that the adjustment is correct in effect.
When you see them on a scope the front one fluctuates much more then the after one.

 

[Mike1alike]

I think the problem might have been the crankshaft sensor that I changed, which caused the spark plugs and sensor to get dirty.

Nope, I wouldn't think it's the crankshaft sensor. It does not give this type of faults. It just tell ECU the crankshaft position. When it goes bad, ECU is not told the engine is revolving and cuts fuel (and ignition usually) off.
Your problem, very rich mixture is exactly that, bad volumes of air/fuel. Usually it's a problem on air feed, not enough air getting in. But sometimes is too much fuel, too.

 

[ccavalles]

Today's update. Spark plug change and sensor contact cleaning. And the start-up has changed a lot, idle too. Still need to take it on the road and see if they get dirty like before. As you rightly mentioned, it would ruin the spark plugs when cleaning them and didn't produce a good spark, and the engine would stall. When I take it out on the street to drive, we'll see, but for now, when it's idle it sounds fine.

 

[bugsymike]

Today's update. Spark plug change and sensor contact cleaning. And the start-up has changed a lot, idle too. Still need to take it on the road and see if they get dirty like before. As you rightly mentioned, it would ruin the spark plugs when cleaning them and didn't produce a good spark, and the engine would stall. When I take it out on the street to drive, we'll see, but for now, when it's idle it sounds fine.

Sounds happier, fingers crossed.

 

[Mike1alike]

Much happier. Congrats!