Can't Diagnose power loss - 2002 311 CDI UK spec


New member
I'm certainly not much of a mechanic, so a lot of this might be mumbo jumbo :)

Recently had a starting problem - it wouldn't ! Then it would .. Last time this happened was several years ago and I was recovered and it was diagnosed as an injector.

At the same time there was power loss and the LOD on the scan gauge would rarely go over 75% .

So, as the symptoms were the same I presumed the same. Took things off for a look and found black death (It's smelt like it for a while) Second time I've had it.

Cleaned it up and changed the injector which was completely lost in tar, presuming it had overheated and worn or something.

Ran great for a day. Then the problem returned. Noticed there was air in the fuel lines. If I took the breather off the fuel filter and filled it with a pipette, it would then start after a short churn. The bi-metalic ? fuel return would just cycle the fuel (MAINLY AIR) though as it was cold (nothing coming from the return to tank). Stopping, pipette, start, repeat would clear most of the air and it would start/run ok. (though I think each time you take the breather screw out 100ml gets syphoned back into the tank as it never seems to completely clear doing it this way).

After a couple of days, noticed the air always returned. As it was due, changed oil, oil filter, air filter, fuel filter (with water sensor). Still the same. Changed the o-rings on the fuel pipes to the fuel filter - fixed.

Ran fine for a couple of days, then power loss. Then no starting ..

Decided I'd changed the wrong injector. Using a flir, the manifold from 1 looked colder, so changed 1.

Ran fine for a couple of days ........ then power loss (today) .. then not starting. Leave it 15 minutes, clean MAF (always looks oily - so also changed the crank case oil separator black cyclone thing on the top of the engine yesterday).

I did order a new maf and housing but ordered the 5 wire one, mine is a 3 .. so need to order another one.

So today .. 75% LOD and about 26 MAP for most of the time. With sometimes 99% LOD and 32 MAP.

Left it running at one stop and the engine note changed. Sounded "growly" like the air is resonating back out. No boost ..

It's done this a few times over the last 15 years, normally I just stop it and re-start and it's fixed.

Didn't want to stop it today so watched the numbers .. MAP 14/15/16 max - LOD - interestingly upto 99% ... ??????

It did the same a few weeks ago before I changed the injectors and it was MAP 14/15/16 and LOD max 75%

So, I'm confused..

I stopped in the end as I couldn't get up hills .. actually, I waited for a downhill straight (not wanting steering lock accident) with no one around, turned it off, turned it on .. no power at all .. rolled to a stop.

... cleaned MAF .. waited .. started .. 26 MAP (max) and 75% LOD (max) - except for the odd time setting off when it shows more for a second.

Any ideas ????????????


UK 2004 T1N 313CDi
Have you scanned for codes with a Sprinter specific scanner? Note your ScanGauge may not read all stored codes if you use that.

Often codes will be stored but will not light the CEL but can identify faults such as loss of vacuum turbo boost control.



New member
Thanks Keith.

Didn't check for codes :) The Scan Gauge says 2 codes, but only shows p0000 , which I think is fairly generic due to not being able to read the real code.

But, as you mention this could be something to do with vacuum turbo boost control, so I'll investigate that further. This might be the problem when it's been sat idling for some time, but doesn't' explain the problem of not starting when hot and randomly loosing power and only showing LOD of 75% and MAP of 26 in those situations.


New member
So this got worse ..

The weird no turbo, vacuum type issue stayed permanent for a day - then fixed itself .. The vacuum was working fine - so no idea what that was.

The 75% injector loading and lower boost got worse/more consistent and mixed with hot start problems, eventually needing 1.5 hours to cool with the bonnet open from engine off to re-start being possible.

For anyone else with the same issue, this was an easy fix. A Faulty Crank Shaft Position sensor (not the crank case position sensor which can also give similar symptoms).

So €10 for a new one and half an hour to change and viola ! Fixed !

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