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Discussion Starter #1
Hi,
I got alfadiag up and running today and have been playing around. I still felt like the car was holding back, so have been looking into what might be doing this.

I logged the lambda sensor over about 8 minutes. The engine was warm as I had been on a few runs, though had stopped for about 10 minutes.

The first few readings say:
Cold or Open Circuit which is fair enough (this lasts for about 33 seconds)

Then, the from about 33 seconds till about 1 minute 10 seconds i get either rich / cold or open circuit (Assume car running richer till its up to temp)

After that it constantly goes between lean and rich. Quite a few times
S.C to Gnd/Sensor lower limit
comes up - anyone knows what this means?

Anyway, it goes between lean, rich and the above, though mostly rish, and hardly ever lean.

Then, its almost equally between S.C to Gnd/Sensor lower limit and Rich. Though a few times here and there Cold or Open Circuit pops up - even 8 minutes in!


What do you think - duff sensor?

There aren't any fault codes coming up by the way
 

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Discussion Starter #2
Oh, also i was getting bad mpg.

I changed the thermostat last week, and measured up 2.97 litres for 22 miles, which was an average day going to work and back. This was 33 mpg which i was happy about - but i dont think i managed to fill up to the top, as I did the test again twice last week - it was something like 12.23 litres for 41 miles (15mpg) and tested again today - 49.6 miles for 12.6 litres (17.9mpg)

Its possible that the thermostat isnt good as it wasnt an oem part, though the car still gets hotter quicker than before.

Also, as I have been playing with alfadiag, i must be losing a few mpg's to the couple of performance runs.

But I still think thats really bad - and would make sense if the car is running rich 80% of the time. What would cause it to run rich? The only thing i can think of is a bad MAF, or indeed if the thermostat isnt good and its getting hotter than before but still not hot enough
 

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Oh, also i was getting bad mpg.

I changed the thermostat last week, and measured up 2.97 litres for 22 miles, which was an average day going to work and back. This was 33 mpg which i was happy about - but i dont think i managed to fill up to the top, as I did the test again twice last week - it was something like 12.23 litres for 41 miles (15mpg) and tested again today - 49.6 miles for 12.6 litres (17.9mpg)

Its possible that the thermostat isnt good as it wasnt an oem part, though the car still gets hotter quicker than before.

Also, as I have been playing with alfadiag, i must be losing a few mpg's to the couple of performance runs.

But I still think thats really bad - and would make sense if the car is running rich 80% of the time. What would cause it to run rich? The only thing i can think of is a bad MAF, or indeed if the thermostat isnt good and its getting hotter than before but still not hot enough
Faulty lambda sensor could also cause this.
 

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I think I have same issue, holding back and bad fuel consumption. I'm gonna try a different Lambda as I changed Maf and no difference.
 
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