Injector re-classification: what does it mean ?

[andreas_t]

Folks,

Can anyone advise me on what the MB dealership means by 'injector re-classification' ? - The injectors were replaced a couple of months ago, but horrible fuel consumption (see other thread) and I'm trying to work out what they REALLY did from the works invoice.

Can anyone advise please ? - Can they also advise on what SHOULD have been done ? - The MB dealer is driving me mad at the moment.

BTW, car is E220CDI W210 model 2001.

 

[se97mlm]

It would be very expensive for a fuel injector manufacturer to make fuel injectors all the same in terms of fuel squirted at a given pressure with a given electrical pulse length. Thus injectors are grouped into sets that have similar characteristics and sets for an engine are matched. They would have changed injectors for ones that closer matched the ones you had.

On older models, this is why all injectors needed to be changed at the same time - as a matched set. Newer technology allows the individual injetors to be coded according to their flow characteristics, and knowing the code of each injector, the ecu can apply the right correction to each cylinder so that all injectors inject the same amount.

More than that i can't say...

 

[silverarrow]

can mean a few things how much was the bill
the cdi injectors are weak and sub standard they are prone to many faults i got rid of my cdi due to fuel leaks o ring leaks no mbz support and lack of care from stealership ie nothing done under warr but no problem when out of warr
speak to www.dieselbob.co.uk or www.uniteddiesel.co.uk ask if recon injectors fitted by mbz from memory about £100 each not from mbz and they only last 100 to 120 k at best

 

[se97mlm]

and they only last 100 to 120 k at best

Don't understand the meaning of that comment: cdi injectors work on the fringes of possibility concerning physics and materials. Think how many injections there are in 100k miles... We don't complain that a set of low profile tyres cost £300 and need replacing after 10k - 30k miles now do we? Spare a thought for the feelings of the guys who design these parts.

 

[Dieselman]

Spare a thought for the feelings of the guys who design these parts.

No.. Go for it.

I understand your comment SE97 but it does seem strange that the old exposed pintle injectors with rubbing surfaces last a lot better than sac hole injectors.

I suspect different material choice ( read more expensive) would alleviate the problem of wear. Think about this many lorries do 100K in a year or two and don't need new injectors. They have been running high pressure injection systems for many years so why don't they suffer?

 

[se97mlm]

It comes down to number of cycles. A lorry engine turns max 2000 rpm, whereas a car 4600rpm. Cars have also more injections per revolution for noise, particle filters etc. so the lifetime is reach more quickly. Also, the truck parts can be made much larger, more space means more material can be used, thus more robust. The nozzle itself is not built to a price- the hole sizes and shape do not allow that. Did you know for example that the holes, although only a few microns in diameter are tapered to help stop lacquering? That kind of process technology just was not necessary on the old systems running at only a few hundred bar injection pressure.

Trucks btw mostly have integrated pump-injector systems like the VW PD systems or individual unit pump and injector systems. These are capable of maximum 2 injections per cycle. Current common rail allows up to 6

 

[Dieselman]

It comes down to number of cycles. A lorry engine turns max 2000 rpm, whereas a car 4600rpm. Cars have also more injections per revolution for noise, particle filters etc. so the lifetime is reach more quickly.

Good point.

Also, the truck parts can be made much larger, more space means more material can be used, thus more robust. The nozzle itself is not built to a price- the hole sizes and shape do not allow that. Did you know for example that the holes, although only a few microns in diameter are tapered to help stop lacquering? That kind of process technology just was not necessary on the old systems running at only a few hundred bar injection pressure.

Nor was it necessary due to the pintle creating a variable spray hole and being self cleaning.

Trucks btw mostly have integrated pump-injector systems like the VW PD systems or individual unit pump and injector systems. These are capable of maximum 2 injections per cycle. Current common rail allows up to 6

This doesn't bode well for systems utillising several pilot injections. This means injector life could be down to about 30K miles.
Are the CR injectors wearing the spray holes or the needle valve?

Lorries have been using EUIs for about 15-20 years without issues, but they still have a fine spray hole. The downsides to EUIs appears to be production costs and lack of fine control.

Another good reason to stick with "Der klunker".

 

[silverarrow]

all i know is modern high pressure direct injection injectors are not lasting as long as customers expect my old 190 diesel 2.5 did 300 k and no real problems but my c200 cdi i got p1ssed off with at 120k way too many faults
moreover bob at diesel bob tuning said loads of cdi merc injectors being recon at the moment and if my memory is correct even mbz up graded the cdi injectors and o rings and seals ummmm ummmm why ??????
perhaps so many leaking the old diesel injectors pre cdi lasted for ages i still feel / think the low sulphur has a lot to do with this.
ask how many cdi owners have had injector problems / recon parts would be interesting