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.

 

[Mike1alike]

I would suspect the intake air control valve located on the throttle body. If it doesn't move free, ECU can't control the air intake and yours looks like almost no air is getting in, like dead IACV.
MES, if you have it (or other diagnose tool) shows you the number of steps IACV is opened and the intake pressure. You should take a look on that.

 

[bugsymike]

When you say you took out the easier sensor (Lambda ?) if that was the one nearer the back of the car, it is the front one that does most work in correcting fuel trim, the back one is to confirm with ECU that it's right. That is the way I understand things.

 

[Mike1alike]

When you say you took out the easier sensor (Lambda ?) if that was the one nearer the back of the car, it is the front one that does most work in correcting fuel trim, the back one is to confirm with ECU that it's right. That is the way I understand things.

That's right and the pre-cat one must be as sooted as the other one. But something else is causing all that rich mixture, my guess.

 

[bugsymike]

That's right and the pre-cat one must be as sooted as the other one. But something else is causing all that rich mixture, my guess.

I just wondered if the pre cat one was faulty or contaminated from the original faulty camshaft sensor wiring at #1.
Electronics not my strong point so just a guess.

 

[Mike1alike]

It might have been. But from my experience, there is not much of a difference in oxygen level reading, sensor clean or sooted. But the level there... That's not just false trimming with too much fuel added. Looks like combustion with no air.

 

[ccavalles]

Thanks for the help. I'm in touch with a friend who has a Fiat Cinquecento and Seicento, and he has offered me parts to try. He lives far away, but he can send them to me. He told me he could give me another throttle body.
Cleaning the lower sensor is because I imagined it was dirty. The other one too, but the access isn’t that easy. The bumper will have to be removed.
The curious thing is how it worked well for the first few kilometers. I imagine it was because the spark plugs were new. Now, even after cleaning them, it still doesn't sound right.
I suppose there's no problem cleaning them with brake cleaner without touching anything.

 

[Mike1alike]

No, there isn't any problem in cleaning the spark plugs with break cleaner. I found something better and that's what I cleaned them with, the last time. Hot water, clothes detergent and citric acid (E330). And wash them with a toothbrush.
A graph with sensors voltage would help. I noticed on mine when I cleaned the plugs, that after cat sensor wasn't quite alive. That made it run rich although everything is saying that after cat sensor is not involved in fuel management. Replacing the sensor fixed it, but as I said, before replacing it I could see on the graph that sensor is not right.
Until getting the testing throttle body, take a look at yours. It looks like this, right, with that little divided part on the opening. That's the channell for the intake valve. Engine running, if you cover that area with your palm or fingers, you should feel vacuum, palm is sucked in. And continuing to cover it should make the engine stop running.
And it can run well at times because usually when it's something wrong with the IACV it doesn't just stop working, but ECU just can't correctly control it's movement. But sometimes it opens enough for the engine to run well.
Usually problem with IACV is the oil vapors coming through breather system that gets sticky after you stop the engine, throttle body still hot for a while. That makes it not move free and if that persists, the electronics in the vslve gets damaged, but can still move sometimes, just not as it should.
One easy thing you can do is clean the IACV with break cleaner. Engine running, spray cleaner inside that little space on the throttle body and open the flap a little to take all in. Can do that on the flap too, oil gets on the throttle walls around the flap. See if that makes it better.

 

[Mike1alike]

And... Woo-hoo! Bravo, Spain! For winning the World Cup!

 

[ccavalles]

No, there isn't any problem in cleaning the spark plugs with break cleaner. I found something better and that's what I cleaned them with, the last time. Hot water, clothes detergent and citric acid (E330). And wash them with a toothbrush.
A graph with sensors voltage would help. I noticed on mine when I cleaned the plugs, that after cat sensor wasn't quite alive. That made it run rich although everything is saying that after cat sensor is not involved in fuel management. Replacing the sensor fixed it, but as I said, before replacing it I could see on the graph that sensor is not right.
Until getting the testing throttle body, take a look at yours. It looks like this, right, with that little divided part on the opening. That's the channell for the intake valve. Engine running, if you cover that area with your palm or fingers, you should feel vacuum, palm is sucked in. And continuing to cover it should make the engine stop running.
And it can run well at times because usually when it's something wrong with the IACV it doesn't just stop working, but ECU just can't correctly control it's movement. But sometimes it opens enough for the engine to run well.
Usually problem with IACV is the oil vapors coming through breather system that gets sticky after you stop the engine, throttle body still hot for a while. That makes it not move free and if that persists, the electronics in the vslve gets damaged, but can still move sometimes, just not as it should.
One easy thing you can do is clean the IACV with break cleaner. Engine running, spray cleaner inside that little space on the throttle body and open the flap a little to take all in. Can do that on the flap too, oil gets on the throttle walls around the flap. See if that makes it better.

Thanks, we will do those tests and thanks for the congratulations on the World Championship!

 

[ccavalles]

Here’s a photo from a while ago. When I made drainage holes for the air conditioner. Water was getting inside. It doesn’t have any type of condensation water outlet. With this, water no longer accumulates in the box.

 

[Mike1alike]

It doesn’t have any type of condensation water outlet.

It should have. A ruber outlet underneath. That can get clogged and if it does, water doesn't drain.

When you'll get to it, I'm interested, if you want to share, the code on the breather pipe there. And maybe a photo showing it, code and more of the pipe. Thanks!

 

[koalar]

It's obviously running very rich

It's going to cause other issues

Plug will start to short out

Pre ignition

Fuel dilution of the oil

And so on


We can physically see it's running very rich, both plugs and exhaust smoke

Is that what the O2 sensors are reporting or are they reporting incorrectly

Whats the volt on the pre cat O2 look like at idle

What's the voltage on the pre cat look like a 2.500K rpm

Post A scan

 

[ccavalles]

It should have. A ruber outlet underneath. That can get clogged and if it does, water doesn't drain.

When you'll get to it, I'm interested, if you want to share, the code on the breather pipe there. And maybe a photo showing it, code and more of the pipe. Thanks!

Following advice I saw in a group, what I did was make some holes in the box.

 

[ccavalles]

nothing disconnected, nothing strange.

 

[Mike1alike]

Video shows there is no vacuum leak.
Spark plugs and O2 sensor show there is not enough (almost none) air feed on idle. The IACV allows air feed on idle. I say that is the first point you need to make sure works correctly, opens when ECU asks it to open and travels free.
You can take the IACV out to clean it if it's not electrically damaged and you can replace it if it is damaged.

 

[Mike1alike]

And yes, reading the O2 voltage on idle and ~2500 RPM can tell a story. But I get that you don't have the diagnose to read it. Is that right?

 

[ccavalles]

Video shows there is no vacuum leak.
Spark plugs and O2 sensor show there is not enough (almost none) air feed on idle. The IACV allows air feed on idle. I say that is the first point you need to make sure works correctly, opens when ECU asks it to open and travels free.
You can take the IACV out to clean it if it's not electrically damaged and you can replace it if it is damaged.

I've cleaned this sensor. If it's the one that goes inside the body, can I use brake cleaner/ contact cleaner on it without taking the assembly apart?

 

[Mike1alike]

I've cleaned this sensor. If it's the one that goes inside the body, can I use brake cleaner/ contact cleaner on it without taking the assembly apart?

The one you cleaned is the MAP sensor. Its data is used too in fuel management.
This is the IACV and you can try cleaning it without taking it out, with engine running spraying brake cleaner/carb cleaner into that slot and opening the throttle flap after you do so, because otherwise engine will stall.

 

[koalar]

And yes, reading the O2 voltage on idle and ~2500 RPM can tell a story. But I get that you don't have the diagnose to read it. Is that right?

Give live data