AIR/FUEL RATIO

[Afour]

Hi All

After watching this weeks wheeler dealers and touching closely on AFR, I thought I would look at mine.

I am using paid TORQUE OBD generic app that connects to ECU via Bluetooth.

Upon starting from cold I was idle at 15:2ish but soon changed to 29:4 after driving.

It stayed at this figure throughout my drive home and at idle once I got home only reducing between gear changes.

my question is this, is this something I should be worried about or is this quite normal or is it just the highly recommended app??

Car is 2010 Citroen C5 2.0 HDI 163bhp auto tourer and is completely stock.

Thanks in advance

Nigel

Edited by Afour on Friday 27th May 12:11

[FordPrefect56]

Jeez.

[stevesingo]

If you Google Diesel engine AFR, you will understand the range which is normal for an diesel engine.

I diesel will run over a wide range of AFR, from about 14:1 at full load on boost, down to 70:1 at a part throttle cruise. Unlike a petrol engine which in emission controlled catalyst equipped engines will be 14.7:1 at part throttle and about 12-13:1 at full load due to the engine output being controlled by the amount of air being ingested (via the throttle), and the correct fuel being added afterwards. A diesel ingests all the air it can and a fuel appropriate to the load is added. Small load= a little fuel added to the ingested air and you get a lean mixture. Large load= more fuel added to the same amount of air and you get a richer mixture.

[Afour]

Thanks Steve

I did google a tad but was mainly finding articles for modded cars with wide band etc, so that's when I thought id come here and ask the good people, that was certainaly a more in depth answer I was looking for other than "jeez" ;-)

Thanks again

[99hjhm]

Is the car running fine?

[stevieturbo]

Afour said:

Hi All

After watching this weeks wheeler dealers and touching closely on AFR, I thought I would look at mine.

I am using paid TORQUE OBD generic app that connects to ECU via Bluetooth.

Upon starting from cold I was idle at 15:2ish but soon changed to 29:4 after driving.

It stayed at this figure throughout my drive home and at idle once I got home only reducing between gear changes.

my question is this, is this something I should be worried about or is this quite normal or is it just the highly recommended app??

Car is 2010 Citroen C5 2.0 HDI 163bhp auto tourer and is completely stock.

Thanks in advance

Nigel

Edited by Afour on Friday 27th May 12:11

To be fair....Jeeez is a pretty suitable response

Especially when used shortly after Wheeler Dealers.....and then a generic app which cannot give accurate or even usable AFR's and then add to that on a diesel.....an american owned auto diesel at that ( stock ? I guess that means standard in English )