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.

 

[bugsymike]

Certainly running very rich, can you get a diagnostic error code read using a good scanner, MES etc.?

 

[ccavalles]

Certainly running very rich, can you get a diagnostic error code read using a good scanner, MES etc.?

OBD2 no error code.

 

[bugsymike]

OBD2 no error code.

No live data / MES etc.
I have had flooding on cold starts with injection down to an issue with temp sensors.
Maybe others on Forum will have a suggestion.

 

[ccavalles]

In this case, the problem came when the sensor cable broke. It started to go bad and then it didn’t start anymore. After changing the cable, it now starts fine, but sometimes not completely smoothly. Now with clean spark plugs, we will see what happens.
The more cared for the car is, the more problems.

 

[bugsymike]

Cam side looks sweet, not impressed with the sensor lead you had to replace and looking at that spark plug I hope you didn't clean it with a wire brush as it destroys the insulation benefit of the ceramic around the centre electrode and causes misfires.
I had that shown me at a Ford Motorcraft lecture 50 years ago.

 

[ccavalles]

Cam side looks sweet, not impressed with the sensor lead you had to replace and looking at that spark plug I hope you didn't clean it with a wire brush as it destroys the insulation benefit of the ceramic around the centre electrode and causes misfires.
I had that shown me at a Ford Motorcraft lecture 50 years ago.

Well, yes I have used them. So following your advice, I will put new ones.

 

[bugsymike]

Well, yes I have used them. So following your advice, I will put new ones.

It was an interesting lecture, even sand blasting a brand new spark plug and testing it showed it started to break down earlier under load.
Ever after that, on all my customers vehicles when servicing I would gap and fit new NGK plugs, never try to clean them. My customers appreciated the attention I put into their vehicles and never queried the cost of a set of spark plugs.
If you just want to get rid of the soot until you know the problem is solved try using a gas blow lamp. Spark plugs are designed to be self cleaning if allowed to run at their normal operating heat range, this is why short stop start journeys are bad for engines , they always run better when at normal (90 degrees Centigrade roughly)
The NGK plugs were as a result of working for a Mazda Dealership in the 70s and seeing how reliable they were. Prior to that I have used Champion, Bosch, Esso, all sorts.

 

[ccavalles]

Thank you for sharing knowledge. You always learn something new.

 

[Pugglt Auld Jock]

It was an interesting lecture, even sand blasting a brand new spark plug and testing it showed it started to break down earlier under load.
Ever after that, on all my customers vehicles when servicing I would gap and fit new NGK plugs, never try to clean them. My customers appreciated the attention I put into their vehicles and never queried the cost of a set of spark plugs.
If you just want to get rid of the soot until you know the problem is solved try using a gas blow lamp. Spark plugs are designed to be self cleaning if allowed to run at their normal operating heat range, this is why short stop start journeys are bad for engines , they always run better when at normal (90 degrees Centigrade roughly)
The NGK plugs were as a result of working for a Mazda Dealership in the 70s and seeing how reliable they were. Prior to that I have used Champion, Bosch, Esso, all sorts.

You're the first person in a very long time to mention this Mike - about how centre electrodes can be damaged by cleaning.

Way way back we all used to grit blast plugs at every service. We had a Champion spark plug cleaning machine which used grit and compressed air, bet you had one too? Cleaning with a wire brush was discouraged because, we were told, metal traces could be transferred to the ceramic surface which could encourage the centre electrode to short to earth which could induce misfire. Then, one day, the the NGK rep gave us a break time talk about how the ceramic was a new formulation and much more liable to be degraded if physically abused so no more grit blasting or wire brushing or any other cleaning. Just gap if necessary and change as recommended. Now, of course, we're not even to attempt to gap modern long life plugs for fear of damaging the very brittle and spindly centre electrodes.

Our boss encouraged the manufacturer reps to give us talks like this and we loved it because the 15 minute tea break could often end up at half an hour! On reflection though, I think he was right to do this as we learned a lot from these talks, even if they were often slanted towards the manufacturer's product.