Evaporative emission purge issue

FR200

FR200
Apr 3, 2017
84
1
London
Hi

I had an issue with a P0441, Evaporative emission issue. Am going to get this N80 valve replaced, but wanted to ask, when this thing plays up, does the car seem to consume more fuel?

Filled up full tank, on half now and I've only done 60 miles. London driving on auto. Is that normal??

Leon FR 200
 

Speed-FReek

Active Member
Jun 12, 2013
1,108
17
South Oxfordshire, UK
60 miles to half a tank? No, something definitely isn't right there, even if you were doing lots of short stop start trips there is no way it should be using up that much fuel.

The tank takes 55 litres (12 Gallons) so that means you are using 27.5 litres (6 Gallons) in 60 miles. That calculates to only 10mpg! :-o

If you can find someone with VCDS or OBDeleven who is near you then it would be worth taking a log of the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) parameters to try and find out how the ECU is actually fuelling your engine.
 

FR200

FR200
Apr 3, 2017
84
1
London
Does this make any sense to you bro
7b30db47e8502c6ce3102a5e15df80f3.jpg


Leon FR 200
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,284
2,713
I don't have an FR. But I've got the P0441 on my Cupra and also my mpg isn't great. But I'm having the N80 done this weekend, so I'll let you know if it improves my MPG anyway. As for the logs, I'm no expert but I thought as long as fuel trims were within 10% you were alright. My long term is 3.5 and short term moves been 0 and -2.7. The video I watched on youtube said if you add em together it should even out. But... hopefully someone who knows what they are doing will be along shortly :)
 

Speed-FReek

Active Member
Jun 12, 2013
1,108
17
South Oxfordshire, UK
I see nothing obviously wrong there with the current fuel trim values displayed. However that said, the values have been taken with the car stationary and idling. If the fuelling has only recently started being a issue then the LTFT value (which is an average value over a long period of time) will likely be skewed.

I would recommend doing the following:-

  1. Reset/Clear the LTFT value so the average value for that starts being calculated from scratch again.
  2. Take the car out on the road (once the engine is up to full operating temperature) and get a passenger to take a note of the STFT values. During normal driving it should mostly remain within the -10% to +10% range.

Then in a few weeks after you've done quite a bit of driving, take another look at the LTFT value which will then have a newly calculated average value covering those few weeks of driving.
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
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Just got back from garage. Full service. New oil, plugs. And had n80 replaced. Made 0 difference to my mpg. Now just have to see if I get evap code again.
 

Speed-FReek

Active Member
Jun 12, 2013
1,108
17
South Oxfordshire, UK
Just got back from garage. Full service. New oil, plugs. And had n80 replaced. Made 0 difference to my mpg. Now just have to see if I get evap code again.

If you've just picked up the car from the garage then surely you're not going to know if the mpg has improved until you've driven it a fair distance? Unless is your garage is 300 miles away (?)

I would ignore any mpg reading on the dash for a while until things have had time to settle down and average themselves back out again.
 

FR200

FR200
Apr 3, 2017
84
1
London
My garage is 200 miles away, and man, it's gone worse. It's like I'm afraid of pressing on the pedal now. And no mad driving, just normal driving. I'm going on Monday to have a full vcds scan, but wanted to know, would that pick all the issues up?

Leon FR 200
 

Steede

Active Member
Jun 23, 2013
119
0
Ireland
I've had that Evap error on my fr replaced the n80 valve and after a while it happend again. Didn't do anything to my mpg though
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,284
2,713
If you've just picked up the car from the garage then surely you're not going to know if the mpg has improved until you've driven it a fair distance? Unless is your garage is 300 miles away (?)

I would ignore any mpg reading on the dash for a while until things have had time to settle down and average themselves back out again.

So far since Saturday I've done 130 miles. Worrying my LTFT has gone up to 11.7. But car seems to drive fine. I've got just above half a tank. I average about 200 miles to a full tank. I'll see how this tank goes, then fill up, reset and see what I get for the next tank.
 

FR200

FR200
Apr 3, 2017
84
1
London
My full tank was about £65, Filled up v power petrol from shell. On empty now, Odo says 170 miles.

Leon FR 200
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,284
2,713
Hmmm, have you previously got better mpg? My Cupra drinks petrol. I get 200 miles to a full tank. I reset the trip counter every time I fill up. So I know exactly how many miles I've got out of a tank. But I spend a lot of time in traffic. Kills the economy. I can imagine if the traffic was insane, I'd be getting 180 miles to a tank.
 
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