320CDI (OM613) Missing a beat.

[ringway]

2002 320CDI (OM613).


I started my engine last night (it had been running for 15, miles 40, minutes before that) and it was a little hesitant to fire up (as though started without waiting for heater plugs to get to temp) and although not too noticeable, ran as though missing a beat on tickover.

When the engine was "missing" the dash lights flickered in unison with the blip.

After turning off and restarting, the car returned to its usual perfect running state. Any ideas?

TIA.

Paul.

 

[BlackC55]

Sounds like a missfire. Possibly from a faulty injector

 

[ringway]

Sounds like a missfire. Possibly from a faulty injector

Cheers Olly, I hope not!

It had 6 new injectors at MB Macclesfield about 18 months ago, but I have noticed that the injectors don't have much insulation aroung the wires to them, so maybe that is related to the problem?


Thanks.

Paul.

 

[BlackC55]

Bung it on a Star and check the injector values jsut to be sure.

Why 6 injectors? They hardly ever go all at the same time!

 

[iscaboy]

Bung it on a Star and check the injector values jsut to be sure.

Why 6 injectors? They hardly ever go all at the same time!

cos you never ever do 1, or 2, you always do the set, so they all present the pump with the same break pressure.

this was of course before the days of common rail rubbish.

 

[ringway]

Bung it on a Star and check the injector values jsut to be sure.

Why 6 injectors? They hardly ever go all at the same time!

Cheers Olly, I'll get it read on star and see what happens.

I had 6 new injectors because MB Macclesfield thought it was a good idea (car was producing a lot of smoke and had been stood for a year before I bought it). Yeah, I know..

It does run superbly now though (apart from the recent blip).

 

[BlackC55]

Well this is a common rail.

Is common rail rubbish?

 

[BlackC55]

Cheers Olly, I'll get it read on star and see what happens.

I had 6 new injectors because MB Macclesfield thought it was a good idea (car was producing a lot of smoke and had been stood for a year before I bought it). Yeah, I know..

It does run superbly now though (apart from the recent blip).

Your fuel pipes are new?

 

[ringway]

cos you never ever do 1, or 2, you always do the set, so they all present the pump with the same break pressure.

this was of course before the days of common rail rubbish.

You can do a single injector as long as you program star to recalibrate the pressure for all 6.

 

[ringway]

Your fuel pipes are new?

Yes. All new now.

 

[BlackC55]

Yes. All new now.

Good. I was wondering if there could be a little air bubble in there causing a slight int miss.

 

[iscaboy]

Common rail isn't new, it's been done before and it had it's problems back then too.

Detroit diesel essentially use a common rail, a high flow fuel pump circuit that feeds each injector, and each injector is its own injection pump too, so the 8v71 would circulate 45 gallons of diesel every minute to the injectors.

I know the new common rails are more electronic, and higher pressure than the detroits for example, but the inherent problems with the system are the same, while on the face of it a simple high pressure pump with no metering or timing integrated sounds a lot better and easier to do than a traditional pump, the fact is the traditional pump has billions of hours of installed use, and does metering and timing extremely well.

The only thing it doesn't do very well is high RPM, hence the introduction of DPA pumps, and of course they brought their own problems (one cracked injector line = no start and pissing leaks if it is running) and it seem to me that CR is an attempt to cure the problems caused by DPA... there was an old woman who swallowed a fly...

and all of this comes back to trying to make lightweight high revving diesels, again, why?

if you want high power and low weight and diesel fuel then go 2 stroke, ideally an opposed piston with no crankshaft like the rootes listers.

diesel only beats petrol on two things in the real world (price per litre per Btu) and that is torque and longevity, but making a diesel lightweight and high revving kills both of those too...

an old and very true saying, people buy the horsepower and drive the torque.

People will diss my old 603.912 as being a weedy 115 BHP, I doubt anyone knows the torque figures, or how they compare to the newer MB 3 litre 6 cylinder diesels.



so back to the question, is common rail rubbish, yes it is, if you want the engine to still be running like new 20 years later, like mine is for example... but not if you want to reduce the build cost of your new 3 litre 6 cylinder diesel engine by around £500 to £750 per engine, then common rail is great.

 

[BlackC55]

I look after a CR car that has done 560,000 miles and it is pretty much all original other than the 'box. They are reliable; maybe not as much as the old style DERV.

But they drive 200 times better are better on fuel etc etc.

I dont agree on all levels.

 

[iscaboy]

I should also say, since we are talking MB here.

The new common rail blue efficiency engine run the common rail at 200 bar, all the time, that is a large energy soak, and the injectors are actuated by piezo electric stacks.

You ask whether this is good or not, well, let me put it this way, the print head of an inkjet printer is, wait for it, a piezo electric stack, it is in functional terms identical to the MB injector, except for two things, one, it uses ink not diesel, two, it is fed at atmospheric pressure not 200 bar.

Know any inkjet printers that will last 20 years?

Know any machine shops that can refurb and repair them when they go wrong?

 

[BlackC55]

I should also say, since we are talking MB here.

The new common rail blue efficiency engine run the common rail at 200 bar, all the time, that is a large energy soak, and the injectors are actuated by piezo electric stacks.

You ask whether this is good or not, well, let me put it this way, the print head of an inkjet printer is, wait for it, a piezo electric stack, it is in functional terms identical to the MB injector, except for two things, one, it uses ink not diesel, to, it is fed at atmospheric pressure not 200 bar.

Know any inkjet printers that will last 20 years?

Know any machine shops that can refurb and repair them when they go wrong?[/QUOTE]

Not yet but give it time.

Lets start a poll!

 

[iscaboy]

Know any machine shops that can refurb and repair them when they go wrong?

Not yet but give it time.

Lets start a poll!

Nope, maybe 100 / 150 years down the time when we can manipulate things routinely at the nano level, until then these components are a lot like hard disk heads, we can assemble them, but not repair them, throw away and fit new is the only option.

I'll grant you that mass outsourced production to china and standardisation across ranges could bring unit costs down to the point where it is the same as changing a spark plug.

but I used to run kit that had spark plugs that were made to be disassembled and repaired or refurbished, not thrown away.

when I started out you rewound and rebuilt dynamos, starters, magnetos, even alternators, now it is all throwaway, and I'm not impressed with it.

 

[ringway]

Good. I was wondering if there could be a little air bubble in there causing a slight int miss.

Good point. I'll have a look.

Apart from the one-off blip the other day she's never missed a beat and I'd like to think there aren't many that run as well as my engine does.

I replaced the long fuel line from the rail to HPP a few weeks ago (the others were replaced a few months ago) so I'll start with that one.

 

[camerafodder]

if you want high power and low weight and diesel fuel then go 2 stroke, ideally an opposed piston with no crankshaft like the rootes listers.

They did have a crankshaft

 

[iscaboy]

They did have a crankshaft

not connected to the pistons though...

I can see this branching off into swash plate motors, aspin heads, lanchester, crossley...

three current threads about problems with CDi, all of which can only happen with CDi, eg leaking rails, kinda supports my assertion...

 

[ringway]

three current threads about problems with CDi, all of which can only happen with CDi, eg leaking rails, kinda supports my assertion...

Erm no..

I don't have a leaking rail!

Read the thread from the start and you'll find out that I had a slight blip on tickover.

I haven't had time to investigate the problem but all has been well since then.

I've driven a 300TD and nice though it is, for fuel economy and performance it is a long way behind the CDI's.