Hard to start w212 e220

[Luxton84]

Hi looking for some advice please.
I have a w212 e220 cdi 2010, in the morning the car will start but cut out straight away then on the second go it will turn over 8-9 times before starting. Once the engine is hot it will start first time every time but leave it 4-5 hours and back to not starting first time. I have done a full service including fuel filter and can't find any fault codes using icarsoft mb v2. There are no obvious fuel leaks and Once started it runs perfectly. Eny help would be greatly appreciated.

 

[alexanderfoti]

The next time it cuts out, turn key off and back to position 2,leave it there for 10 seconds then go straight to start.

If it starts, issue is with low pressure side, air leak or something similar.

 

[Luxton84]

The next time it cuts out, turn key off and back to position 2,leave it there for 10 seconds then go straight to start.

If it starts, issue is with low pressure side, air leak or something similar.

Iv tried this but it makes no difference. On the second try it turns over 8-9 times then starts regardless of the time I allow it to prime. I suspected air getting in the fuel lines myself as a number of my old Mercs had that issue (o-rings in the fuel line) however this engine (om651) has apparently resolved this issue with difference fuel lines.

 

[alexanderfoti]

That engine can still get the problem, but it's internal to the HPpump where the air gets trapped.

In your cars, its probably leak off from the injectors, it needs a leak off test carried out and some monitoring of the rail pressure when it won't start.

 

[Luxton84]

That engine can still get the problem, but it's internal to the HPpump where the air gets trapped.

In your cars, its probably leak off from the injectors, it needs a leak off test carried out and some monitoring of the rail pressure when it won't start.

OK thanks for your help

 

[Exp21]

Hi, can't you from icarsoft check the rail pressure during cranking when it won't start? You could make an idea

 

[alexanderfoti]

Yes it will tell if it it's not starting due to low rail pressure but then you have to find where its going.

 

[Luxton84]

Hi, can't you from icarsoft check the rail pressure during cranking when it won't start? You could make an idea

Yes I can, it's between 3-4 bar with low pressure before start and 350ish bar high pressure on idle.

 

[Luxton84]

Yes it will tell if it it's not starting due to low rail pressure but then you have to find where its going.

The rail pressure is all good. I don't believe it's pressure related as icarsoft is showing 3-4 bar low (before engine starts) and 350+ high on idle.

 

[alexanderfoti]

The rail pressure is all good. I don't believe it's pressure related as icarsoft is showing 3-4 bar low (before engine starts) and 350+ high on idle.

Min rail pressure to start is 240-260Bar

 

[Luxton84]

Min rail pressure to start is 240-260Bar

Yes it is when cranking... well more like 300 then once started and idling it then settles at around 350.
When the key is in position 2 (the one before cranking) the fuel pump is activated and the pressure goes from 0 to 3-4 bar. Once the engine is warm it will start first time and all of these figures stay exactly the same.

 

[alexanderfoti]

Ah I see, so you have 300 bar and no start?

 

[Luxton84]

Ah I see, so you have 300 bar and no start?

Yes, I don't think the issue if fuel or pressure related.

 

[alexanderfoti]

can you check cam/crank sync during non start?

 

[Luxton84]

can you check cam/crank sync during non start?

Yes I did and that was interesting. During the first start of the day (when I know it won't start first time) the icarsoft said "cam/crank no sync limp home mode" yet on the second attempt to start the car (when I know it will start) it did sync successfully. I only discovered this a couple of hours ago when I tried starting the the for the first time today. Iv just ordered a new camshaft sensor. Hopefully this will resolve the issue. Personally I thought camshaft sensors where only a problem when the engine was hot but that might not be the case.

 

[alexanderfoti]

Yes I did and that was interesting. During the first start of the day (when I know it won't start first time) the icarsoft said "cam/crank no sync limp home mode" yet on the second attempt to start the car (when I know it will start) it did sync successfully. I only discovered this a couple of hours ago when I tried starting the the for the first time today. Iv just ordered a new camshaft sensor. Hopefully this will resolve the issue. Personally I thought camshaft sensors where only a problem when the engine was hot but that might not be the case.

Does seem to point to cam or crank. I suppose next step is to see which value stops changing during crank (cam or crank) on actual values. Could be battery voltage related.

 

[alexanderfoti]

Could also be worn chain/failing tensioner. How many miles?

 

[Luxton84]

Does seem to point to cam or crank. I suppose next step is to see which value stops changing during crank (cam or crank) on actual values. Could be battery voltage related.

I did suspect battery as its only showing 12.55v when the car is off and engine not running which is only just about executable. Its showing 14+v when the engine is running so I know the alternator is ok. I would suspect other issues if it was the battery though. As mentioned above once the engine has started everything else is spot on. I think my next step is to replace the camshaft sensor then go from there

 

[Luxton84]

Could also be worn chain/failing tensioner. How many miles?

120,000 miles. I know the om651 engine is known for timing chain issues but there is no unusual sounds during start up or eny unusual noise at all.

 

[alexanderfoti]

120,000 miles. I know the om651 engine is known for timing chain issues but there is no unusual sounds during start up or eny unusual noise at all.

Unlikely to be chain at that mileage IMO