[Wouter XC70 D5 2011]

Hi all,

I have a 2011 XC70 with a D5 engine in it. It's my first "modern" Diesel and my first Volvo. It runs like a dream and I'm very happy with it.
Having worked on petrol cars before I used fuel trim a lot to give me an indication of engine "health".

Having recently picked up an Icarsoft Vol 3.0 scan tool I've been searching everywhere but I do not seem to be able to find any values resembling fuel trim on my car.

I have used the search extensively but came up blank so far.

My question is: Is fuel trim a value used in D5 diesel engine diagnostics ?
Am I looking in the wrong place or is the icarsoft vol 3.0 not able to show me fuel trim values? (seeing that it can access all available modules in the car and display the most obscure sensor values and perform resets on just about anything I find that hard to believe)

If fuel trim is not a value we look at in the D5 engine, what are some values to monitor or where can I find some more background information on general Diesel OBD diagnostics?

Who can point me in the right direction? tnx!

 

[Dyno]

I don't believe there is anything equivalent to the Fuel Trim that you find in in gas engines. The fuel trim values are generated while the engine is in closed-loop A/F control mode, and diesels generally run open-loop. They simply don't need the degree of A/F precision that gassers do.

Watch boost, injection pressure, and any channels and codes related to the aftertreatment system and you should be good.

 

[Wouter XC70 D5 2011]

I don't believe there is anything equivalent to the Fuel Trim that you find in in gas engines. The fuel trim values are generated while the engine is in closed-loop A/F control mode, and diesels generally run open-loop. They simply don't need the degree of A/F precision that gassers do.

Watch boost, injection pressure, and any channels and codes related to the aftertreatment system and you should be good.

Thanks for your reply! What you say makes sense although I do not yet understand how else a modern diesel would know how or what to compensate when it is not reaching stochiometric.
Did find myself a copy of "troubleshooting and repairing diesels" by Paul Dempsey. Only 400 pages until I should be a bit more "educated"

I will have a look at the boost and injection pressure values as well and find out what they can tell me.
Must say that a lot of information on the subject seems pretty hidden away. I guess most people only look at the data once stuff is already broken. Unfortunately for me I'm not most people 🤓

 

[Dyno]

You need to understand two essential diesel facts...
1. Air/fuel ratio is HIGHLY variable during normal operation (approx. 30:1 at full load and maybe 100:1 at idle)
2. Diesels never approach stoichiometric A/F. They always run "lean". Stoich is appox. 15:1 and as mentioned above, the closest they come is about 30:1.

Unless you have one of these...

 

[Dyno]

An acquaintance of mine...

Triple turbo inline-6 IH diesel.

Something to aspire to, perhaps.

 

[Wouter XC70 D5 2011]

You need to understand two essential diesel facts...
1. Air/fuel ratio is HIGHLY variable during normal operation (approx. 30:1 at full load and maybe 100:1 at idle)
2. Diesels never approach stoichiometric A/F. They always run "lean". Stoich is appox. 15:1 and as mentioned above, the closest they come is about 30:1.

Thank you! I feel like a whole new world has been opened up to me.
I dig the triple turbo build. Those are some insane fabrication skills!

For now I will just try to get a grasp of diesel mechanics and aim at having my D5 run healthy and reliably before I start stacking those turbo's

 

[Dyno]

I have diesel fuel in my veins and am happy go as deep down the rabbit hole as you can stand.