I have some limited tuning experience with hptuners and Mopar but none on Mercedes. I have just installed an OETUNING tune in my 2010 e350 cab and logged some fueling data with torque app today. To my surprise at WOT this thing is sitting at +25% short term fuel trim both banks and +20% long term trim on one bank and about +16% the other bank. Is this normal for these ECU's?

At part throttle LTFT often goes to +22%.

In the Mopar world part fuel trims like this would be close to setting a lean code but as mopar goes open loop at WOT and this thing seems to stay closed loop if have nothing to compare it too.

Gut feel is that the fueling in the tune is wrong either in fuel mass or pulse width. But its just gut feel.

Also at WOT it targets 13.5 to 13.3 I am used to best power AFR being closer to 13?

It does run OK and does not seem to knock. I have written to them to ask.

Comments?

Seems you have an exhaust or intake leak gong by these trims. Please clear adaptations via Xentry and monitor trims after checking for leaks.
For all technical support, please email sales@oetuning.com

Thanks.

How do I get hold of Xentry. All I have is dimsport tool.

I did email already.

I will check trims on stock tune.

I am used to adaptions being reset when tune is flashed. Is this the case on mercedes?

Its a dealer level tool. Many independent service centers own this equipment. For diagnosis, we recommend a trained MB tech with the required tools for the job.
MyGenius is just an OBD2 flash tool and is not designed for diagnosis.

I am using the torque app to measure trims and I am starting to think it does not report fuel trims correctly for this ecu.

It would be a huge favour if someone with torque and an m272 could take a look at what torque reports for their car for short and long term fuel trims. I have read other reports that say generic trim information. Is reported differently and Mercedes uses something cal!ex mixture forumulation percentage. Xentry reports different values to generic obdc
Please?

Unfortunately and app cannot replace a trained tech and a fully functioning diagnostic tool as far as identifying the issue and moving forward.
It sounds like over oiling your Green Filters has fouled your MAF. Due to this, we recommend dry filters on all MAF based cars to avoid unnecessary issues.

I took a look at the maf last night and the wire is all bright and shiny so I am not sure that is the issue. The vehicle drives well and is as economical as ever. If I had not looked at the trims I would be none the wiser. The filters are out of the box and have never been re oiled. I will get hold of some maf cleaner and some dry filters non the less.

I am leaning towards the idea that the Toque app incorrectly reports values for vehicles that are perpetually in closed loop (at least when not coasting)


I will thank you OETuning for your advice and support. When I get to the bottom of this rabbit hole I will post the result so as to share the love.

Now if someone with Torque and an M272 could just log some fuel trim data this would all be over in a jiffy.

Busted MAF. When I picked up the fuel trim issue I think it was dying because trims were haywire but it still managed to achieve commanded AFR pretty much. Then I cleaned the MAF with liqui moly MAF cleaner and that killed it. Almost straight away a code P0172 and P0175 which means it maxed out on fuel trims trying to fix a lean condition.

Just sharing.