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Technical Soot issue

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Technical Soot issue

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David66

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Yo guys, new here.
I have a Fiat 500 1.2 petrol 2007. It has started to run rough and "jump a beat" while driving. I have noticed black smoke and a smell of petrol. OBD codes = 0. Checked the MAF....a bit wet, dryed it out. Took out the plugs and found them totally black sooted. Took out both O2 sensors with the same result. What the heck can it be....help?
 
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I'm thinking a leaking injector, or all of them if all plugs black.
Simple answer is too much fuel for the air.
A blocked filter will stifle the engine, but the air flow sensor should just inject less fuel. If the first oxygen sensor identifies the incorrect mixture, the ECU should weaken it off, although it will be constrained by limits, and the second oxy sensor will confirm or deny the catalyst is doing its stuff.
An ignition misfire will also cause these symptoms. Poor fitting plug leads can cause misfires, and the coils will work harder to get the spark out, which then causes coil failure. Make sure the leads fit onto the plug tops properly (sometimes difficult when the rubber boot grips hard).
Ideally you need software to read live data, so the fuelling and ignition can be 'seen'. that should show up injection or ignition issues.
 
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But 4 leaking injector overnight is a bit unlogical for me. As there are no codes for me to read out maybe something out of the odinary must be looked at?
Is there a way to measure the MAF sensor while running? maybe that thing is a bit off.
 
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I believe this car has a MAP sensor instead if it's naturally aspirated engine. Turbo engine has MAF.

So let's just assume that the car was serviced properly and it has good spark plugs. If you drive only short distances, there would be soot. It'll all clear and self-clean when you start driving longer distances.

If the engine burns a little oil, there would be soot too. :unsure: No EML for that.

How about PCV breather hoses? Evap?
 
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Great answers, thanks.
MAP / MAF...patatoe pataatoe, its the same sensor I am refering to. I swapped that for new one and the issue is a bit less (ie restless motor, black smoke), but still there. Took the O2 sensor off without much difference to the engine problem but then of course error code P0135 popped up. I will be off on a long drive tomorrow which will give me a better idea of the MAP sensor and if that was the problem.
I can let you all know that the plugs are brand new, MAP sensor brand new, 2 x O2 6 months old (they are my next suspicion even though they are new, they are not original and maybe have led to this issue). Both O2 sensors have been cleaned but clogged up with soot very quickly again.
The car starts without a hich, runs in neutral without a hich and has this "hiccup" while driving along most probably because of too rich a mix.
 
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The old O2 sensors had gone 250.000km and began to give error codes on and off. MAP sensor is a a product from Ie+ (whoever they are). It was the only sensor they had in store and I had to move a step in troubleshooting :). But why should other products than Bosch give more issues?
 
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I had one, car went into limp mode and was practically impossible to drive. Code was for range/performance. Changed back to old Bosch sensor, which still worked and it fixed it. Replaced it anyway when found a good deal on a genuine one because integrated temperature sensor wasn't showing accurate values. Then I stopped changing sensors when I learned how foolish it was.

I'm afraid that you should take into account an unlucky possibility that you have an oil burner there. That may be the reason why the sensors failed, not just the old age. It's quite high mileage already. Are all the lambda sensors genuine Bosch too? I've heard stories that only Bosch lambda sensors work properly while others may upset the fuel mixture completely. Also when sensors give codes, you should reset the code after replacing the sensor so that ECU can adapt. However catalyst might have failed if you had got a code for the 2nd lambda. :unsure: Hopefully it's not. Good luck.
 
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David66 said:
The car starts without a hich, runs in neutral without a hich and has this "hiccup" while driving along most probably because of too rich a mix.
Click to expand...

It's the lambada sensor.

If yours is a strange brand you never heard of, or unbranded, or spliced into the wiring of the original connector, rather than having its own connector, then dump it.

The "hiccup" you notice (I'm going to guess it's around 1600-1800rpm) is when the lambda heater switches off, since at that point the exhaust gas is hot enough to keep the sensor going. If the lambda is weak, frail or faulty, it can't cope without the heater helping it, and it goes into "surrender" mode, so the ECU takes over and switches to a default fuelling map, which is rich.

Buy an OE, Bosch or NTK lambda. They cost a fortune, but they have the one upside that they actually work.

You could try breakers to get a low mileage one from another car... but make sure the plug connector shape matches yours and that the length of the cable will be long enough, since there are different Euro- spec' cars out there, even with the same engine, so there's a potential difference in the sensors.


Ralf S.
 
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Ralf S. said:
It's the lambada sensor.

If yours is a strange brand you never heard of, or unbranded, or spliced into the wiring of the original connector, rather than having its own connector, then dump it.

The "hiccup" you notice (I'm going to guess it's around 1600-1800rpm) is when the lambda heater switches off, since at that point the exhaust gas is hot enough to keep the sensor going. If the lambda is weak, frail or faulty, it can't cope without the heater helping it, and it goes into "surrender" mode, so the ECU takes over and switches to a default fuelling map, which is rich.

Buy an OE, Bosch or NTK lambda. They cost a fortune, but they have the one upside that they actually work.

You could try breakers to get a low mileage one from another car... but make sure the plug connector shape matches yours and that the length of the cable will be long enough, since there are different Euro- spec' cars out there, even with the same engine, so there's a potential difference in the sensors.


Ralf S.
Click to expand...
Hi Ralf
Thanks for a concrete answer. Others have also anwered with their experiences of non-Bosch components. I have actually driven the car with the Lambda sensor disconnected and it drove better (but still a lot of petrol running through the system of course), but withou the hiccups. I found out that they are of american origin. I will be trying a couple of used original ones this weekend to see if there is any difference.
I will get back to this thread with an answer a soon as I have feedback :)
Regards
 
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If it's American it should be reasonably okay, quality-wise. It may be worth tracking down the lambda relay (not sure whether 500s have one.. but older cars used to) and/or making sure that the lambda sensor is getting current and is sending out the correct signals. I think the signal variance is something like +/- 0.5A ... which is why even a small variance or poor connection (especially the spliced-in wiring type) can cause problems.


Ralf S.
 
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David66 said:
Hi Ralf
Thanks for a concrete answer. Others have also anwered with their experiences of non-Bosch components. I have actually driven the car with the Lambda sensor disconnected and it drove better (but still a lot of petrol running through the system of course), but withou the hiccups. I found out that they are of american origin. I will be trying a couple of used original ones this weekend to see if there is any difference.
I will get back to this thread with an answer a soon as I have feedback :)
Regards
Click to expand...
I did wonder about the lambda this is why I suggested disconnecting it, yes the car will run a little rich but they always do when going off the mapping only, I was trying to think what would cause too much fuel and thought duff inputs would possibly cause too much fuel?

Note on the Bosch part finder there are different ones for Euro 6 and earlier so make sure you get the correct one
this maybe the correct one https://www.boschaftermarket.com/gb...sors/products/F00HL00356/vi/vehicle/SVNKJrIS/

 
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SOLVED!
Lets just go through what was done.
1.) MAF/MAP = little change. Maybe due to worn out sensor but did not solve the issue.
2.) Only checked the idle valve because of maybe restricted air flow.....worked fine.
3.) Changed sparkplugs and cables because of milage (60.000 miles). No change.
4.) O2 1 + O2 2. Both cleaned and swapped around with no change. Found a used one at the local car dump (from a Punto 1.2). little change
5.) Changed electronic distributer with on found at local dump. BIG Change but not quite there.
6.) Changed camshaft sensor with one found at the local dump.....bang on = Solved the issue entirely

So thanks to the crashed Punto at the local dump with doner parts the car is running perfectly again. I would also like to thankyou all of you guys with good input and ideas. And by the way ALL parts changed on my car are Champion and/or Hella

Have a great day :)
 
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Ignition coil in proper english....sorry :)
see attached foto
 

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