Stuck with this ML and need some advice

Orlando Technician Ontario Posted   Latest  
2011 Mercedes-Benz ML350 Bluetec 4Matic 3.0L (642.820) 7-spd (722.9)
Excessive Fuel Consompution

Hello all. I have this ML350 Blutec that is about to drive me up the wall. Customer brought it in with a concern of excessive fuel consumption. This how ever is after the software was modified to remove DPF monitoring. I believe the vehicle was setting codes for a DPF and a cleaning didn't resolve it. So after the software was modified he claims that his fuel economy went from about 800+ km/tank to about 600, maybe 650 at best.

When sitting in the car idling the range data on the instrument panel drop pretty fast. You can lose about 8-10km of range in a minute or so just idling. The bar graph that shows you your L/100km usage is pegged max at 20+L/100km. As your city driving the milage drops at a steady rate. Hit the highway and it will start to climb a bit after so steady driving. A few minutes ago I started the vehicle and it showed 627km left. Went for a short drive, got back and it showed 484! I parked it and midway through writing this I went to move it and it was at 602km remaining.

I asked my boss to call the guy who modified the software so we can have him flash it back to stock. I have a very good feeling that whatever was done to the software somehow messed with the ECM can't see anything in the data stream that would point me to something being off. One of the NOX sesnors is broke, a DPF temp sensor isn't working and apparently the "tuner" may have removed the Adblue module. Of course the car hasn't set a code for any of these things. I think I may have been chasing my tail over errors someone else made.

Before I see if I can get the stock software put back in, is there anything else I can check for on the vehicle that may dedicate why it's behaving like this? Thanks.

Caleb Technician
Caleb Default

Was the exhaust system removed? Did the tune just stop monitoring the DEF, DPF, SCR,and EGR systems or did he actually shut them off so that EGR is always closed, DEF never sprays and regen never occurs???? If he shut off these systems as most "delete tunes" do without putting a straight pipe exhaust on it he is going to very quickly clog the DPF Filter. If I was you I would put the car outside…

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Orlando Technician
Orlando Default

SO I just got some more info. It didn't have a DPF issue, in fact it had an issue with the SCR. Something was changed and it didn't fix the issue so the pump was removed and the software modded. It look like he disabled the SCR and DPF system because if I unplug the DPF sensor it never sets a code for it, or the non working temp sensor. I don't think anything was done with the EGR system because…

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Robert Engineer
North Carolina
Robert Default

Hello Orlando, Caleb has told you exactly right. Also Ontario probably has emissions inspection. I would not put my name on this car even if it is a good customer unless he wants to put everything right again. If the trap is there it is certainly plugged up. bob

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Mike Technician
Mike Default

Think ur right plugged filter on exaust side , we have a truck taking the system off . Then taking with other shop mangers in area for semi trucks they have Sean shops remove the Def part block of part then filters plug up . Also think,they said 2025 or something going for 0 emmiss stuff out the exaust system

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