DIY EOBD and Injector overfuelling check (CDI2)

stumo

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ML270CDI x3 2002,03,04 | Sprinter 316CDI 2003 LWB
I have created an OBD2 ELM327-like Bluetooth device that gives you access to many more channels in your CDI2 car. Normal off-the-shelf ELM327 devices only give you very basic channels on CDI2, mine gives those and extra channels.
Extra channels like:
  • Engine oil temperature
  • Transmission oil temperature*
  • Fuel rail pressure
  • Fuel low pressure
  • Fuel temperature
  • Commanded EGR control
  • Commanded boost control
  • MAF
  • Injection volume (giving accurate fuel consumption)
  • Engine torque*
  • Torque converter torque*
  • Transmission speed sensors*
  • Actual Gear position*
  • MB Star "smooth running" injector test.
  • Read and clear codes.
*722.6 transmission only.

The device plugs into your OBD port just like any other ELM327, but it gives you a lot more info. Just connect it to any BT OBD2 app like Torque.

The smooth running test is done in the background every time the car is stationary and at idle. There are configurable parameters to set thresholds (ECT, RPM, LOD) for the smooth running test to start/stop.

The smooth running test (usually done using MB Star Diag) puts the ECU into a special mode where it measures individual cylinder accelerations. The ECU then adjusts each fuel injector volume to try to keep the accels even. This means an injector with a relatively large negative correction is overfuelling. If you catch that situation early enough, you can save your engine/vehicle from the scrapheap.

MB Star says you need to do the test at idle and Neutral. I have found that a bad injector shows up better in D if you have a 722.6. For this reason, my device will do the test any time the engine is at idle regardless of gear.

I have released the Arduino source code I wrote free of charge, because I like to contribute to this community with ideas and methods to keep your vehicles running longer.

So you have everything you need to make your own device same as mine at the following link.
https://sprinter-source.com/forums/index.php?threads/87110/post-914245

I use an old Samsung android phone with the Torque Pro app as a permanent mini-dashboard. (See more photos in that linked thread).
20200801_102937_HDR.jpg

I am considering making a small batch of these for people who can't make their own. These will be based on ESP32 rather than Arduino and will also have WiFi and an extra EOBD ISO15765 CAN socket so that things like a HUD can be plugged in as well. If you are interested let me know.

I may also be able to create a version of this for CDI3 if there is demand.

CDI2 vehicles are OM611, OM612 and OM613 powered cars, SUVs and vans circa 98-06'.
 
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MinionBob

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Nice work.

I think you would get more uptake if you put a price on the forum for the ones you make.
 
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stumo

stumo

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Your Mercedes
ML270CDI x3 2002,03,04 | Sprinter 316CDI 2003 LWB
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Its on the Sprinter forum link, I think I would do them for AUD$200 +shipping, but I haven't prototyped out exactly what hardware/connectors/case I would use yet.

You could make the Arduino version yourself for under $100 in parts depending on where you buy. Add a few hours of soldering time.

Its a very nice upgrade to older vehicles though. Its good to keep an eye on oil temps and trans temps especially if you tow or drive a heavy Sprinter like a motorhome. And the continuous background overfuelling injector test could save you a small fortune if an injector goes bad and starts melting down a piston.
 
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