Troublesome limp mode on 2006 315CDI

veezee

New member
Hi everyone,

I am experiencing serious issues fixing a limp mode happening with my NCV3 10/2006 315CDI sprinter here in Europe (Belgium). Maybe there will be some suggestions out there about what to do? It has 210,000km and is equipped with the OM646 engine (2,148 cc, 148 hp). This model is equipped with a sequential twin turbo. The vehicle is in very good condition for age, but....

History of what has been done:

  • The vehicle entered limp mode and was diagnosed by Mercedes dealership as needing turbo replacement. Restart of the engine did not fix the problem. Engine light/pictograph was on.

  • Turbo was replaced by family mechanic using a reconditioned turbo. It did not fix the limp mode. It came back after driving 10km.

  • Error code was P2359 (in French: regulation de la pression de suralimentation - Avarie de fonction). The limp was usually triggered by being on a relatively steep road, often on highways (gear 6) but not always (it can also happen on gear 3 of manual gearbox).

  • The two electrovannes of the turbo (also called pressure converter I think) were then changed, thinking it was the next most logical move. The car went fine for 400km and then limp mode came back. At this stage, restart of the engine was fixing the problem for a moment. Same error code.

  • We happened to be in another country when that happened and so the car was checked by another mechanic (UK). He did a smoke test to search for leaks and could not find anything. From his experience of this model, he changed some electrical wiring (3 wires) linked to the turbo that can often be a problem in these models because they accumulate water and can become faulty. That did not fix the problem. Limp mode was coming regularly, but totally randomly. Not obvious pattern of why it happened except usually on steepish road.

  • The mechanic then checked/changed from spare sprinter all the sensor he could find but without any success. Limp mode was coming back.

  • Then vacuum pump was changed because it seemed that changing the electrovannes earlier helped having limp mode coming back less often and somehow the vacuum pump is linked these pressure sensors. But again with no success. Limp mode came back, this time after 500km.

This is where I am at. The UK mechanic thinks that the turbo that was installed by the family mechanic is faulty. I believe he is genuine in his thinking because he did not charge anything for all the work he did (because he did not find the fault). The family mechanic does not think it is the turbo causing the limp mode because of the the type of turbo it is. It is not a variable one, it is very mechanical so if it was faulty, the limp mode would not be triggered so randomly and would be more noisy (which is not the case, it seems to be running smoothly). It would be more systematic (his words).

Would there be any suggestion by some expert in this forum for potential things to look at? I know the EGR valve is one but the UK mechanic was saying that there would be another error code showing up. Any help would be greatly greatly (greatly) appreciated.

Thanks,
Vincent
 

Eric Experience

Well-known member
Vincent.
Your engine is very close to the end of its life at 200km. To find this particular problem you need to use a vacuum gauge to monitor the vacuum operating the turbos. Vacuum leaks can cause the ECU to loose control of the turbo. To determine the health of your engine measure the oil pressure at idle when hot. Eric.
 

veezee

New member
Hi Éric. Thanks for the reply. Quite surprised hearing 200,000km means close to the end of such an engine. This goes against everything I have seen so far with lots of them going 400,000km if well looked after.
About the test younpropose, could you give me a bit more information about what it woukd show me. Would it point towards an engine failure?
Thanks for the help,
Vincent
 

Eric Experience

Well-known member
Vincent
The 150 hp engine fails due to main bearing caps flexing. The test point for oil pressure is on the timing case cover near the belt tensioner it on the intersection of 3 stiffening ribs. The plug is a 10 x1 thread. Eric.
 

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