Black Smoke only at Low Fuel Level

[scottgilliland2003]

Hello,

hopefully someone one can help with this?

2002 Clio DCi 65

the car runs perfect since I bought it last year with the odd minor wee problem which has never been a lot

being a dci of it's age it has the usual wee puff of black smoke, really nothing ever to worry about or sometimes even noticeable

Lately though over the last few months I've only noticed that when the car fuel level hits about 2 bars above empty it spews out smoke, starts off with more than the usual puff and by the time you hit 1 bar above empty even a small incline will make the car behind you disappear

it doesn't really become down on power but it will huff and wee but by being less responsive then when it gets going is when the smoke starts

The usual has been looked at like egr etc but that was only cleaned last week, this morning was the worst I have seen it.

i stopped at a garage put £20 in which brought it up to half, drove off and no more smoke even when you out the foot down

could it be a bad fuel level sensor? When the car is around 2 bars it's actually empty and sucking up some of the 12 year old dirt in the tank (if any)?

i assume it's not something serious if it's black smoke since that would mean excessive diesel rather than blue being oil? But fuel economy is never impacted as I still get around 500-600 miles to a tank

 

[scottgilliland2003]

Ok so as I said today is worst I have seen it and it continued to do it on the way home

You speed up slowly after maintaining a continuous speed and the car hinders, then you apply more throttle, a huge puff of smoke and as you speed up it disappears

seems to be around the 1.5-2k rev where it mainly hinders, ended up driving home through rush hour in 3rd gear at 50mph to stop people behind me flashing there lights

anyone have any idea at all?

thanks

 

[H182]

I have absolutely no idea, but if it only does it when the fuel level is low, keep it topped up above half a tank till you find a solution. Better for the car and the people behind.

 

[scottgilliland2003]

I have absolutely no idea, but if it only does it when the fuel level is low, keep it topped up above half a tank till you find a solution. Better for the car and the people behind.

It didnt do it on the way home after i had filled up

I have since then unplugged the EGR Valve and drove to work with not a sign of smoke and surprisingly not even an engine light since I unplugged the valve

I assume the EGR is faulty, causing less air to be reused in engine meaning fuel was burning? Not sure if thats correct but its how I am looking at it

Will know for definite tonight when I drive home using cars headlights behind me to check for signs of smoke

thanks for the reply

 

[sburrell93]

What you described in the second post is definitely the egr. I've had the exact same issues, same rev range everything. It's been faulty since I bought the car and I've just ran with it unplugged lol, stops all the black smoke!

The basics of it are the egr should close off completely under full throttle, only allowing clean air through. If it's faulty/stuck it'll be letting through recirculated exhaust air and so the fuel won't be burning cleanly, hence the black smoke.

 

[MartinR]

Egr valve. Take it off and give it a good clean.

 

[scottgilliland2003]

The egr was taken off the day prior to this post and cleaned

ive ran it two days with no egr plugged in and the car sounds better, pulls better and mpg shot up to 72mpg too, I did reset it but it usually would sit round 65mpg

so very pleased it wasn't anything major just a faulty ergr by the sounds of it

is there any issues running with no egr?

i plugged the OBD machine in and it didn't even bring up an error to say the egr was disconnected?