Limp home mode OM648
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Joined: Dec 2012
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Limp home mode OM648
So... My status on the car...
2004 W211 320cdi automatic gearbox.
My friend cleaned out the DPF catalyst and the next day I went to the computer company. Ofc I got check engine light after driving a couple of miles with empty dpf. But after optimization the car seems to go in limp home mode.
The ECU guy believes it has something to do with the engine, I tried to unplug EGR and oxygen sensor 1. But still it's in limp home mode.
When starting the car i can Rew it to 4500rpm about 2 seconds and it goes to 2999rpm (limp mode)...
He said that he fixed everything with dpf sensors and EGR. So those values should not give the limp home mode.
- 500000 km
- swirl flap mod
- Cleaned(emptied) DPF
- Company optimized ECU and removed DPF and EGR values.
- no fault codes (except some for the instrument cluster, but I had these codes before and it run ok)
Last edited by Thomas Wester; Sep 20, 2021 at 09:33 AM. Reason: Pictures
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Yes. But none. First time you can rev it to ~4500rpm and it goes down to 2999rpm with full throttle.
EGR was cleaned and worked before deleting it through ECU programming and I had full power even with ECL on after cleaning the DPF catalyst.
Swirl flaps newer was an issue but I made the mod anyway. Should not have anything to do with limp home mode. I tested to remove the 4,7k ohm resistor and check engine code "swirl flap" came on. So that's ok.
The car runs great, but slow.. i wanted to get 280hp instead of 80hp after this fix 😅
EGR was cleaned and worked before deleting it through ECU programming and I had full power even with ECL on after cleaning the DPF catalyst.
Swirl flaps newer was an issue but I made the mod anyway. Should not have anything to do with limp home mode. I tested to remove the 4,7k ohm resistor and check engine code "swirl flap" came on. So that's ok.
The car runs great, but slow.. i wanted to get 280hp instead of 80hp after this fix 😅
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Joined: Jun 2016
Posts: 161
Likes: 33
From: Orlando, Florida
2005 E320 CDI (SOLD); 2008 ML320 CDI 4MATIC
Your scanner snapshot indicates your engine is om642 V6. OM648 is an inline 6 & I don't think MB installed DPF on any of those. Snapshot indicates boost pressure & temperature readings that are implausible. Intake manifold pressure appears to be significantly lower than atmospheric. Vaporized oil from CCV is recovered through turbo inlet & can coalesce in intercooler & seize up 'swirl flaps' range of motion also. The CDI-4 control unit will reset itself between drive cycles & allow engine to operate at full power until implausible value is encountered & reported by one or more sensors to trigger limp mode. In my case, turbo actuator was culprit but I'm thinking your issue is more complex. How was DPF cleaned? Back pressure of exhaust reporting 0 hpa & downstream temperature sensor reporting implausible value + soot content of DPF reporting 128% would tend to indicate engine is struggling to 'breathe' due to back-pressure of exhaust. A clogged DPF is like having bananas in tailpipe so if engine is unable to exhale, logic dictates it will be unable to inhale as well until exhaust constriction is cleared. There should be 'Stored & Current' DTCs in CDI-4 from these implausible sensor readings. I suspect DPF is source of your troubles.
Last edited by PSDCampervan; Sep 20, 2021 at 07:11 PM.
Thread Starter
Newbie
Joined: Dec 2012
Posts: 5
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Your scanner snapshot indicates your engine is om642 V6. OM648 is an inline 6 & I don't think MB installed DPF on any of those. Snapshot indicates boost pressure & temperature readings that are implausible. Intake manifold pressure appears to be significantly lower than atmospheric. Vaporized oil from CCV is recovered through turbo inlet & can coalesce in intercooler & seize up 'swirl flaps' range of motion also. The CDI-4 control unit will reset itself between drive cycles & allow engine to operate at full power until implausible value is encountered & reported by one or more sensors to trigger limp mode. In my case, turbo actuator was culprit but I'm thinking your issue is more complex. How was DPF cleaned? Back pressure of exhaust reporting 0 hpa & downstream temperature sensor reporting implausible value + soot content of DPF reporting 128% would tend to indicate engine is struggling to 'breathe' due to back-pressure of exhaust. A clogged DPF is like having bananas in tailpipe so if engine is unable to exhale, logic dictates it will be unable to inhale as well until exhaust constriction is cleared. There should be 'Stored & Current' DTCs in CDI-4 from these implausible sensor readings. I suspect DPF is source of your troubles.
I made the wrong engine settings on Delphi obd reader. It is the OM648 engine.
The DPF is empty. I don't know why it says 128% when it's empty.
Do you think it's possible the swirl flaps are the issue? They are not even connected to the swirl flaps engine. And as i mentioned i made the 4,7k ohm mod.
But no fault codes what so ever. I will connect the Delphi unit again and change engine settings and see if it changes values.
Last edited by Thomas Wester; Sep 21, 2021 at 01:24 AM. Reason: Pictures
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Joined: Apr 2007
Posts: 633
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From: USA
2006 E320 CDI
if the swirl flaps’ link rod is disconnected from the servo motor then the swirl flaps can move from pressure, they should be tie wired open so they can’t move.
Last edited by ot1; Oct 10, 2021 at 07:51 PM.
