PD or Common Rail

[asthpsw]

I'm looking for another TDI up to 4 years old, the problem is I want a body style similar to my 2001 Toledo .................so there isn't a Seat suitable so I'm looking for a VW Jetta although if the car / price was right I would go for an Exeo or an A4.

The Salesman at the dealers don't seem to knowledgable when it comes to PD or Common Rail.

Is there a definate advantage of Common Rail over a PD (even if only less strain on the Cam Belt !)

How can I tell if a 2.0 Litre 140BHP TDI engine is a PD or Common Rail. Are all 2.0 Engines 16V

Is there anywhere I can tell by when the car was first registered.

What is VW's equalvalent to the S-Line ?

Paul

 

[Riggz1]

Hi, I would go for the CR unit every time. I have had no DPF issues at all.
Also I believe R-Line is VW sports trim line

 

[bald_eagle]

PD all the way,
legendary engines,power and torque no contest,use the right oil and they go on forever,check these forums and you will find very few cambelt issues and any there are are usually from incorrect fitting.

i would recommend the 1.9 130bhp asz engine if available in a car your after

 

[asthpsw]

I know I raised the question last year but I want to see if experience (ie more time since the CR has been out) if anyone has got any more comments on PD vs CR and problems with either that are unique to each type of injection system ?.....am I right in saying there is more to go wrong on the PD ? (with 4 individual Pumps ?). The reason I ask is I've been searching for a Leon Sport with a CR engine yet I can save myself £1000-£2000 by going for a PD unit............
Is the cam belt change interval more frequent on the PD ? (ie 16 Valves & 4 high pressure pumps to operate cams for ?

Thanks

Paul

Paul

 

[Seatmann]

The PD has a pump, four separate solenoid injectors, it's really not that different to the common rail. The PD is also a very tried and tested engine that's very easy to tune.

 

[markmeus]

My Ibiza is common rail, advantages that I can see over PD are that it is quieter, and costs less to tax. Otherwise it's much of a muchness. PD engines are easier to tune, ECU protection on the CR engines makes it harder.

Also PD engines seem to provide more consistent fuel consumption, CR can range from poor to very good, depending on the colour of the moon and how far you pulled your socks up! (In all seriousness though my MPG does seem very variable depending on temperature.

 

[eta76]

leave the 170bhp 2.0 TDI PD... and go for the CR
Lots of DPF problems, many have two-mass-flywheel problems, injector seem to fail at a number of engines. There is a recall for them in the UK. In The Netherlands they keep ignoring the problems..

 

[Seatmann]

The CR was only brought out to deal with emissions but if like me you blame cows for that then let the car fart it's heart out

 

[asthpsw]

The PD has a pump, four separate solenoid injectors, it's really not that different to the common rail. The PD is also a very tried and tested engine that's very easy to tune.

Thanks from everyone, I thought that the PD had a pump as you say but then 4 individual pumps on the injectors "PD" (controlled by the solenoids) and it is these pumps that cause extra stress on the camshafts thus on the cambelt (more so when going to 16 valves) and also the reason why the oil for PD's have to have a high shear stress level.

The CR I thought had one very high pressure pump fed to a single "pipe" shall we say which the injectors get their feed from.

Paul

 

[Muttley]

Well, the cam failure associated with using the wrong lubrication on a PD engine is of the exhaust cam lobes and lifters, so that's where the worst shear stress is found. The PD cams have roller rockers.

The 2 litre engines, PD and CR, both have four-valve heads and all-roller rockers. The CR engine is based on the PD, replacing the PD injectors with common rail ones, leaving the valves, rockers and cam lobes the same.

The CR pump is driven by the cambelt, which is longer in the CR engine and takes a very convoluted path, as the CR pump is hung off the front of the cylinder head. As with all the TDI engines, the coolant pump is still driven by the cambelt.

 

[asthpsw]

Thanks to all.
I went and tried a Leon Sport 2009 59 reg with 140bhp PD engine (thought I'd give it a go in view of above comments) the only problem I had was the fact it only had any 'torque' after about 2000RPM then it shot off .....is the normal ? The car has only 20K on the clock. It was a bit disappointing as my dear old 110bhp pre PD with 113K on clock picks up well from 1500 RPM (at thats with sticky vanes)
Is that right what I experienced in the PD ?
Paul

 

[eta76]

170bhp here.. And I had the same thoughts.. Had a chipped 110bhp to 140bhp. And had massive torque from 1000rpm (for as I remember it )
It is harder to make a nice dragstrip start. As it does little at the lower rpm's.
But I was told the massive torque in the lower rpm's was a killer for crankshaft etc.. So I still thinks it sucks.. But it is a nice experience when the torque come in.

 

[Seatmann]

I think it's because they're 16 valve engines, not sure but I know that's what it's like with N/A petrol engines with 16 valves, all the poke is further up the rev range.

 

[asthpsw]

Thanks I can understand that in a N/A petrol engine due to the lower intake / exhaust velocity - but this was very un-nerving at roundabouts and junctions it was much the same as when my old 110bhp had just gone into limp mode and pulling away at junctions. A 143 CR Exeo that I drove recently had power from below 1800RPM.
Paul

 

[Muttley]

More aggressive emission control on the later engines limits the power that can be delivered at lower revs. Basically, California hates diesels.

 

[asthpsw]

thanks again however wouldn't I have found that on the Exeo 143bhp CR as this is even newer than the Leon PD unit we are discussing.

Paul

 

[Muttley]

The move to CR was prompted by the fact that the PD system isn't able to perform the tricks needed to get the emissions down. CR injectors can deliver fuel at full pressure in several different, variable, doses at any time during the firing stroke. The PD injector has a built-in two-stage profile and varies injection quantity by cutting off the tail of the delivery. Not good enough any more.

 

[asthpsw]

Thanks Muttley - So the lack of torque in the 16V PD is down to more efficent injection control ? Was thinking earlier I used to drive an old 130BHP 1.9 PD Audi A3 (ie 8 Valve) and there was torque right from 1000RPM - the Leon PD I tried yesterday ought to have a health warning . 'beware no torque below 2100' ! I can't believe thats how VW /Audi wanted it.
Paul

 

[Muttley]

There's probably more than one factor at work here.

The TDI 140 Sport has a Front-mounted intercooler (like my older TDI 150 Sport, but a different IC design) which means more pipework and a larger pressurised volume between turbo and inlet. Combined with the larger turbo on the Sport model this can make for some slight delay before the boost builds at low revs, compared to an engine like the old TDI 110 ASV, with its SMIC and short pipes. You may well find the boost and torque is there, just after a split-seconds delay.

Beware of talking about efficiency in the same sentence as emission control. All emission control measures make the engine less efficient, meaning less mpg. Such abominations as EGR actually increase the particulate emission ("smoke") as well as decreasing the efficiency - the purpose of EGR is to reduce peak combustion temperatures to inhibit the formation of nitrogen oxides, NOx.

So the CR diesel as installed in the car isn't necessarily more efficient, but can be made so, with its complete flexibility with respect to injection timing, quantity and pressure. This allows better combustion control at lower revs (multiple small injection quantities, I think) getting back some of the torque that the PD loses when subject to later emission control regs. I haven't researched this a great deal, mind, and I could be wide of the mark.

 

[asthpsw]

Thanks again Muttley from what I seen of your previous advice over the years on this site you are probably bang on the money. Picking up on something you've said : taking the 140 BHP engine regardless of whether its a 16v PD or CR if it sits in a 'Sport' version of the car then it has a different IC ? (and resulting pipework ?)

You've said the magic word ERG that would be the first thing I'd want to turn off or reduce. (this is to stop inlet clogging) but from what you say there could be other benefits.

I must admit I was expecting others to have noticed the drop in low down power on the 16v PD that I was expecting loads of replys saying that they had thought the same.

Paul