w211 320 cdi faulty injectors ?

[mark123]

hi
had mb 24 hour breakdown out yesterday as engine turning over but not firing up.
he plugged in a computer which came up with nothing, so he sprayed (what i think was) easy start or something similar into engine whilst i turned it over, the car started and the technician advised me that the fuel injectors were at fault. is this a common symptom as i cant find anyone else with similar problems?
also, i have started the car this morning and it works fine
im a complete novice when it comes to mechanics so im at the mercy of the garage
any help would be greatly appreciated
thanks in advance

 

[Number_Cruncher]

I would be extremely wary about that diagnosis. How does starting the engine using Easy Start (yuk!) tell you that the injectors are faulty? Suely after the Easy Start has done its damage, for the engine to keep running, the injectors have to work.

Is this a common rail equipped car?

If so, I would be looking more at how well the fuel pressure builds up during cranking. If the pressure doesn't build up enough, the ECU won't signal the injectors to open at all.

 

[mark123]

thanks for the advice number cruncher.
how do i tell if it is a common rail?
would the car run for any length of time if it was the injectors as i went out for 5 mins this morning and it seemed fine?
what dammage does easy start do ? as i just put my trust in the technician as he was from mb, now i am worried

 

[Number_Cruncher]

>>now I am worried


Please don't allow me to worry you - I don't know enough about the specifics of these cars to be taken all that seriously.

If your car is a common rail diesel, then what I do know is you can't do diagnostics on them with a can of Easy Start - the system is really quite complex, and poke and hope repairs will cost you dearly. Effectively what I'm saying is that you should expect to see more evidence of what the fault actually is before you buy parts to fix the problem.

Also, with common rail engines, you are almost better off going to a diesel injection specialist rather than to a dealer. Poke and hope is, sadly, still a common way of attempting to fix faults.

 

[mark123]

hi number cruncher
done a bit of research cdi stands for common rail direct injection ! so yes it is a common rail, as the car is under warranty i am taking it to the garage tommorow so hopefully they will be able to fix it under the warranty terms.

thanks again

 

[Number_Cruncher]

>>yes it is a common rail

Yes, I *thought* so.

Effectively, the engine managemnt computer needs to see certain values from key sensors in the system, notably the pressure sensor in the common rail, before it will begin to signal the injectors.

Perhaps by using some sniff, the engine began to turn quickly enough for the fuel pressure to rise beyond the threshold. But, that's just a guess - the proof will be seen when the live data are reviewed during a cold start.

If it's all covered by warranty, then you may not be too bothered if the garage tries a poke and hope repair rather than doing a thorough diagnosis - that way, you get more new bits on your engine! ;-)

 

[compress ignite]

"Easy Start" (Ether)

I know Ether is a big No No for pre-chamber diesels like 617,602,603 series.

'Burns out the glow plugs...and/or superheats the inside of the combustion
chamber... for starters.

Generally if it needs Ether...and gets it...it will soon need even more very
expensive repairs.

 

[Dieselman]

The injectors have a habit of leaking air into the system on switch off. This stops the engine starting until enough fuel has been passed to force out the air.

Have the injectors leak off flow tested.

 

[sweeper]

I would be extremely wary about that diagnosis. How does starting the engine using Easy Start (yuk!) tell you that the injectors are faulty? Suely after the Easy Start has done its damage, for the engine to keep running, the injectors have to work.

Is this a common rail equipped car?

If so, I would be looking more at how well the fuel pressure builds up during cranking. If the pressure doesn't build up enough, the ECU won't signal the injectors to open at all.

I agree completely, i had an AA man out to one of our leased vans at work as it wouldn't start, i pointed out to him that the van had experienced the same fault a year before and it had lost electrical power to the ecu this showed up by not bringing the glow plug light on, so without checking anything he pulled the air intake pipe of and squirted easy start in! "what the ***k are you doing" i said, "well your glow plugs aren't working and this will get it going" my reply was "i'll leave you to it then" and walked back in the workshop, bearing in mind this was a direct injection engine, not a cold day either, it wouldn't have needed glow plugs to start, 10mins later he was towing me to the local VW dealer.
One problem with the diagnostics on a modern engine, people plug the box in and it says no faults and they're lost, i had one recently, vehicle wouldn't start (common rail DI engine) plugs in diagnostics and no faults recorded, now you have to go in a read the parameters as you try and start and look for an abnormality in the figures, in this particular case there was low fuel pressure and a new pump was required. Perhaps these technicians require more training? I know some of ours do!

 

[Dieselman]

plugs in diagnostics and no faults recorded, now you have to go in a read the parameters as you try and start and look for an abnormality in the figures, in this particular case there was low fuel pressure and a new pump was required.

Surely that should have recorded low rail pressure.