I was just wondering if anyone has experienced these engines and would care to pass comment.
I've read the various magazine write-ups and it seems they have impressed the average journalist.
My wonder, asides from how they drive, is how reliable the units are. As I understand it, the common rail injection system is more advanced than that used in the various HDi engines, but on an HDi engine what is it's weak point? My money is on the injector pump being the weakest link on the TDCi engines, given the pressure it works at.
Cheers
Hew
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HDI engines, as used in Peugeot/Citroen cars ARE common rail (1st generation), and I believe that the TDCI engines use the 2nd generation common rail systems as do Renault with their latest dCI engines. I think these 2nd generation injection systems are manufactured by Delphi. Sorry, that is all I know, I cannot help with the expected reliability though, but I have a feeling some others will!
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Yes, the fuel injection branch of Lucas was taken on by Delphi but of course theirs is not the only common rail system. I am not familiar with the precise technicalities of the 2nd generation systems but the following may interest those who want to know the basic differences between the old 'pump-line-injector' (PLI) systems and the newer common rail systems.
The PLI system has a high pressure pump supplying fuel via a separate pipe to each injector with each injection event being controlled by the pump. Since fluids are virtually incompressible, the timing, volume and pressure seen by the fuel at the pump end of the pipe causes a 'squirt' of similar characteristics from the injector end . However any wear in the pump or injector, any imbalance in the length or bore diameter of the pipes, or any swelling of the wall of the pipe under pressure, will slightly alter the injection characteristics.
In a common rail system, the whole system is charged at the same pressure, which is usually much higher than in the PLI system so as to achieve very fine atomisation of the fuel from the injector and thus more complete and even burning and hence lower fuel consumption and emissions. The start and finish of each injection event is electronically controlled AT THE INJECTOR so can be more precisely timed than in the PLI system. A small pilot injection can 'light the fire' before the main charge is injected and so lead to a more gradual and quieter combustion and less emissions. (In very simple terms, a fast rise in pressure generates 'knock' and a fast rise in temperature generates nitrous oxides (NOx).) It is also possible (though I don't know if it is done in practice) for the ECU to monitor the injection timing and compensate for any wear in the injector.
These are some of the advantages of the common rail system. There might be a small chance of reduced reliability but the systems are so well made that I wouldn't think this is anything to be unduly concerned about. As an example of the precision engineering of these systems, it can cost an engine manufacturer more to buy in just the fuel injection pump of a PLI system than to make the whole of the rest of the engine.
The worst scenario might be 'hosing', i.e. an injector sticking open and allowing fuel under pressure to pour into the cylinder and cause serious damage but I haven't heard of this on a passenger car engine. There are some systems where the ECU can detect a sticking injector and close it down in microseconds to avoid hosing (I don't know if this is possible on passenger car systems).
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Delphi are what used to be called CAV/Lucas/Rotodiesel;I think.
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Does this engine still use a timing belt like the Tddi or has it gone over to a chain ?
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as far as i can tell there is a belt between the pump and the camshaft. I'm not sure how the drive gets to the pump. Hopefully there aren't two belts!
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Seems that the 2.0 Tdci in the Mondeo has a chain doing all the work, but the 1.8 Tdci in the Focus has a combination chain from crank to pump and belt from pump to cam just like the old Ford 1.8 diesel. Have just driven a second generation common rail diesel in the Citroen C3 and can tell you it's very quiet and refined. Feels like a petrol engine to drive, but with more torque. The best engine choice in the C3. And that's just the 70bhp 8v version. There's a 92bhp 16v on the way as well.
HJ
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I have driven both Focus and Mondeo TDCi. Both are quite lively with characteristics like an LPT petrol. The Focus one seemed a lot more refined.
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