c220cdi injectors

turbospud

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my 75k 2003 220cdi is suffering from uneven idle almost a misfire at idle only runs fine when up from idle,fairly certain its an injector thats not functioning right,its been on star and shows nothing untoward,so how do i know which one it could be or do all of them need overhauled
 

rpe2

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It is the same on Mrs E's C270. Suspect an injector worn as smooth running test shows 2x injectors only just within spec. If star shows nothing untoward, it may be an expensive shopping trip to achieve not much.
 

Alex Crow

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smooth running test on star is pretty much always diagnostic of injector idling faults. the mechanic should also have done a das compression test, especially if no injectors exceeded the +5mm/hub maximum value.

did your man do these tests turbospud? these type of injector faults never log codes....
 
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turbospud

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think it was code faults he was looking for but none showed,the screen shows m/s time for each injector which would have been within limits.
i suspect its the nozzles or the injector itself thats not right,but how do i find which one it is when its mechanical rather than electronic.
it is something that will need repaired because its an auto,tickover is very rough
 

MB TECH WARRINGTON

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think it was code faults he was looking for but none showed,the screen shows m/s time for each injector which would have been within limits.
i suspect its the nozzles or the injector itself thats not right,but how do i find which one it is when its mechanical rather than electronic.
it is something that will need repaired because its an auto,tickover is very rough

2 ways to test, individual injector quantity correction on star, a rough running caused by injector would show in the actual values but will not give a fault code.

or leak off test using measuring apparatus#

A special tool is only as good as the person using it, i find that most using them are tools themselves.:rolleyes:
 

Alex Crow

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think it was code faults he was looking for but none showed,the screen shows m/s time for each injector which would have been within limits.
i suspect its the nozzles or the injector itself thats not right,but how do i find which one it is when its mechanical rather than electronic.
it is something that will need repaired because its an auto,tickover is very rough

i suspect that, as mb tech says, your expert is somewhat less than expert!

the symptoms you describe are classic for an injector fault, he wasted his time looking for fault codes and should have concentrated on the smooth running and compression test, as i said.

you say that the 'm/s (sic) time .........would have been within limits' but did you see the screen, and do you know for sure exactly which computer sytem was used - mb quantify injection for cdi engines in mm3/hub (cubic milimeters per stroke) not the ms (milliseconds of injection period) used for me engines.

it is always possible that we misunderstand your symptoms or cause, but if it were an injector fault, whether electronic or mechanical (invariably mechanical) the das (star) tests would have picked it up.

the smooth running feature of your engine management uses highly accurate crankshaft speed data to asses the acceleration provided by each power stroke. it constantly alters the correction amounts for each cylinder to achieve 'smooth running', it is these correction quantities that the smooth running monitor screen displays. the ecu will only correct within certain limits, and it is an injector that is running at the maximum limit that we are looking for - ie an injector that fails to deliver the needed crankshaft acceleration, even with the maximum possible correction factor.

i pity your poor expert being subjected to this informed scrutiny though, perhaps as i said we misunderstand your problem!! could even be collapsed engine mounting - hard to say from my keyboard.;)

good luck turbospud, and keep us informed. :D
 
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turbospud

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i suspect that, as mb tech says, your expert is somewhat less than expert!

the symptoms you describe are classic for an injector fault, he wasted his time looking for fault codes and should have concentrated on the smooth running and compression test, as i said.

you say that the 'm/s (sic) time .........would have been within limits' but did you see the screen, and do you know for sure exactly which computer sytem was used - mb quantify injection for cdi engines in mm3/hub (cubic milimeters per stroke) not the ms (milliseconds of injection period) used for me engines.

it is always possible that we misunderstand your symptoms or cause, but if it were an injector fault, whether electronic or mechanical (invariably mechanical) the das (star) tests would have picked it up.

the smooth running feature of your engine management uses highly accurate crankshaft speed data to asses the acceleration provided by each power stroke. it constantly alters the correction amounts for each cylinder to achieve 'smooth running', it is these correction quantities that the smooth running monitor screen displays. the ecu will only correct within certain limits, and it is an injector that is running at the maximum limit that we are looking for - ie an injector that fails to deliver the needed crankshaft acceleration, even with the maximum possible correction factor.

i pity your poor expert being subjected to this informed scrutiny though, perhaps as i said we misunderstand your problem!! could even be collapsed engine mounting - hard to say from my keyboard.;)

good luck turbospud, and keep us informed. :D

thank you both,i think he dosent know enough on how to use it properly but im not qualified to use it either,as you say someone with more experience will narrow it down,i did see the screen which showed engine running data but wouldnt know what values should be there and he didnt do any smooth running tests.
compression test on cylinders would not be needed i think, as it runs fine when above tickover.
i think even i would find a collapsed engine mount:lol:,the movement on the engine at idle has been enough to wear out the air filter rubber mountings though
 
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turbospud

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to update this for future referance it was one of the injectors that was faulty,didnt show on star or leak off the first time,retested recently on leak off and there was a slight extra amount comming from no4,new one fitted at £180 now running smoothly and returning 53mpg :D
 

rolfy

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Hi Spud

Had a very similar problem to yours and, because there were no fault codes, Indy thought it was transmission/torque converter related (car would judder at low revs). ATF change and some American tranny fix did nothing.

It was only when he actually drove the car that he realised it was engine related and found a worn injector tip causing a misfire under low fuel loads. It was on this forum (Wireman et al) that the possibility of an injector problem was first raised.

Like, you c.£180 on a new injector fixed the problem.

Wonder how many torque converters have been replaced to "solve" this problem?

Glad you got sorted.
 
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turbospud

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its just as well it wasnt at the main dealer they would have changed all the injectors and the torque converter:lol:must have been a worn tip or gunged with the supermarket crap that the wifey puts in it.
it has taken a while to show itself as faulty
 

Martin Jennings

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A lesson I learned ages ago! Never use supermarket crap diesel! Been loads of discussion on here about it as well. Glad you got it sorted anyway.
 

rf065

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A lesson I learned ages ago! Never use supermarket crap diesel! Been loads of discussion on here about it as well. Glad you got it sorted anyway.

That would be the same crap supermarket diesel that comes from the same refinery as everyone else's diesel? :confused:

Russ
 


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