D3 Start issues with a twist (maybe??)

It’s called a crank position sensor on our engines (CPS) and yes, they’re temp sensitive and can cause these issues. It’s a ***** to change with access behind the turbo and drive shafts. It a a four hour job to get to, but doable without body or engine removal. I had mine done and all my weird start issues were solved.

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Originally Posted by Eric SDV6SE

I'd be taking it to a diesel fuel injection specialist and getting them to do a leak down test of the injectors, you'll probably find that whilst they are getting pulses, they are probably reaching the limits of their flow range ( I.e they are wearing out). Reason for poor starting is that they cannot atomise the fuel enough to create combustion. As you said, you have o2cand pressure, so fuel being the only variable, and if pressure from thr lp and hp pump is good, it has to be on the fuel rail, and most likely injectors. The pcv in the fuel rail can stick too, but that usually gives a code, so I'm leaning toward your injectors being the culprit. If they are, best bet is to replace all 6, don't forget you'll need new fuel connection pipes and crush washers too, usually provided with the new injectors.

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To be that bad you would have low rail pressure while cranking.

Engine Starting
During starting, the fuel rail pressure must be at least 150 bar. Should the pressure be below this figure, the injectors will
not operate, resulting in the vehicle not starting

Which is about 2200psi before it'll fire injectors.

If they were not atomising the fuel you would have white smoke aswell

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Originally Posted by Graeme

It's located on the left side on the TDV6.

Crank angle sensors can deteriorate with age. Monitor its live values as the engine is cranked to see the stability or otherwise of the signal produced.

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Thanks for your comments everyone.

Is the live value visible through a Gap tool? I had a quick look this morning and couldn't see it listed.

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Originally Posted by josh.huber

To be that bad you would have low rail pressure while cranking.

Engine Starting
During starting, the fuel rail pressure must be at least 150 bar. Should the pressure be below this figure, the injectors will
not operate, resulting in the vehicle not starting

Which is about 2200psi before it'll fire injectors.

If they were not atomising the fuel you would have white smoke aswell

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Thanks Josh,

If the pressure is too low, will the ECU not signal the injectors or do the injectors have the smarts to refuse?

I want to clarify as our mechanic advised he was seeing pulsing to the injectors.

Michael

The Gap tool can show live values for the crankshaft position sensor.
The injectors don't have any smarts so seeing pulses means that they should be opening.

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Originally Posted by swiftnets

Thanks Josh,

If the pressure is too low, will the ECU not signal the injectors or do the injectors have the smarts to refuse?

I want to clarify as our mechanic advised he was seeing pulsing to the injectors.

Michael

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Hey mate, as graham said if the ECU doesn't see enough pressure it won't signal the injectors. But if it isn't seeing crank position it also won't. It would be best to get a decent Auto eject to scope the crank position sensor. Especially if it plays up all the time. Doesn't have to be an LR expert. You can buy the manuals with the diagrams off this website. And they are a bargain.

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Originally Posted by Graeme

The Gap tool can show live values for the crankshaft position sensor.
The injectors don't have any smarts so seeing pulses means that they should be opening.

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I must be missing something, or my app is. I have looked through the complete list of live values and can't see one that says what I understand to be Crankshaft Position Sensor.

Thanks again for all the suggestions.

Graph live values, engine, engine rpm, which is taken from the crankshaft position sensor. The rpm should increase in a couple of steps from turning over prior to firing, then the first fire increases the revs substantially then proper idle revs. Any dips or zero moments indicates a faulty sensor.

Be good to graph it against the rail pressure too

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Originally Posted by josh.huber

Be good to graph it against the rail pressure too

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https://uploads.tapatalk-cdn.com/202...ff64bd0ed7.jpg

This was a hot start. I'll do a cold start later, but at least you should see engine speed before rail pressure