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  #1  
Old 07-21-2010, 09:20 AM
latief's Avatar
1993 300E 2.8- M104
 
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Location: Gainesville, FL
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How to diagnose bad injector(s)?

This seems to me to be a tough one, but how can one diagnose a bad injector? evermore, what goes bad in the injector anyways? when i worked on mine, i did not see any areas that could potentially fail other than seals, pintle cap...etc..

I am talking mainly about the ones on the m104 engine......

Thanks

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  #2  
Old 07-21-2010, 01:15 PM
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Not to hyjack, but to draw more info: if one were to replace their injectors, namely in a w124 (103 OR 104), are they just a drop in replacement (other than changing the seals/holders)? Or are these something that need balanced and tested like I've always heard the diesel ones should be?
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  #3  
Old 07-21-2010, 01:49 PM
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Quote:
Originally Posted by MattBelliveau View Post
Not to hyjack, but to draw more info: if one were to replace their injectors, namely in a w124 (103 OR 104), are they just a drop in replacement (other than changing the seals/holders)? Or are these something that need balanced and tested like I've always heard the diesel ones should be?
You'd need to get your replacements pop tested by someone or do it yourself...
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
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  #4  
Old 07-21-2010, 01:51 PM
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Quote:
Originally Posted by latief View Post
This seems to me to be a tough one, but how can one diagnose a bad injector? evermore, what goes bad in the injector anyways? when i worked on mine, i did not see any areas that could potentially fail other than seals, pintle cap...etc..

I am talking mainly about the ones on the m104 engine......

Thanks
Usually people talk about too much smoke and poor idle / poor mpg - eventually the injectors get blamed and replaced.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #5  
Old 07-21-2010, 03:14 PM
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Originally Posted by Army View Post
You'd need to get your replacements pop tested by someone or do it yourself...
And this just confirms that they are working correctly before they are installed, right?
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Old 07-22-2010, 03:11 AM
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Originally Posted by MattBelliveau View Post
And this just confirms that they are working correctly before they are installed, right?
From the little I know - having never done the job yet - you need to set the pressure at which they spray out the fuel. New ones are not balanced they are just assembled. I've just bought some reconditioned ones from a supplier in the UK that balanced them for me. They set the pressure to be slightly higher than the specified (as per the FSM) to allow bedding in.

These are mechanical components that wear and so I guess somewhere there will be a gap that gets bigger as a result of use which in turn I guess will change the pressure at which these things spray.

When I fitted by new reconditioned injectors I also replaced the heat shields which (I have read here) are meant to be a one time fit only - they provide a seal between the injector and the pre-chamber.
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #7  
Old 07-22-2010, 05:48 AM
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I replaced all 6 on my M103 and cured the hard starting problem I had even though they only had 60K miles on them. Wish I had done it sooner.
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  #8  
Old 07-22-2010, 07:08 AM
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M103 injectors are a third of the price of M104 injectors.

You don't bother playing around refurbing M103 injectors - just replace them with new.
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  #9  
Old 07-22-2010, 07:50 PM
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Hello, i have never uploaded a file before, but hopefully this works and the following info can be of some use to you: http://www.filefactory.com/file/b2af194/n/fuelinjectors.pdf (if anyone knows of a better way to host a file please let me know )

From past experience, CLOGGED electronic fuel injectors seem to cause: 1. poor mileage and 2 poor performance.


NOTE *** A couple of the previous posters have posted info about their injectors, however we need to realize that there are numerous types of injectors out there. In Army's case i believe that he is talking about DIESEL INJECTORS which i believe can be cleaned and calibrated. and tilac1 i believe is refering to MECHANICAL INJECTORS(for a gasoline engine) and i am not sure wheter or not these can be calibrated.

to Latief. i have the same M104 as you, and we have ELECTRONIC FUEL Injectors, which can be ultrasonically cleaned, however from what the guy at the Bosch fuel injector service shop told me, they can not be calibrated. As long as the injectors are clean, they should all flow the same. he also mentioned that MB fuel injectors do not respond well to cleaning.

HAve your injectors flow tested, and make sure that they are all within atleast 5% of each other. all 6 of mine had nearly identical flow, however one of them leaked, so i had to replace it, because the leak caused rough startups.

good luck
tim

Last edited by timmyr; 07-22-2010 at 08:24 PM. Reason: can not get link to work
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  #10  
Old 07-22-2010, 08:35 PM
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Quote:
Originally Posted by latief View Post
This seems to me to be a tough one, but how can one diagnose a bad injector? evermore, what goes bad in the injector anyways? when i worked on mine, i did not see any areas that could potentially fail other than seals, pintle cap...etc..

I am talking mainly about the ones on the m104 engine......

Thanks
Your EFI injectors can be flow tested as previously mentioned. Otherwise they can be cleaned and thats about it. These injectors are extremely reliable (much more so than the Kjet injectors in the M103) so they normally work or don't work. I rare cases they can leak but this is a symptom of a failed fuel filter.

Your mercedes uses the same style EV1 injectors.
http://fordfuelinjection.com/?p=82

The same type of Bosch injectors were used on millions of other non mercedes cars. You can look up the PN on the side of the injector (start wtih '0280 xxx xxx') and find another set of EV1 or EV6 injectors from another car that flow the same rate.
http://www.witchhunter.com/injectordata1.php4

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  #11  
Old 07-22-2010, 10:46 PM
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1993 300E 2.8- M104
 
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Thanks for the valuable info tjts...i guess they should be fine,,,,i am still dealing with a mixture off issue, and I have changed everything i could think off except for the injectors...I am not planning to change those any time soon since they cost a fortune....
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  #12  
Old 07-22-2010, 11:07 PM
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Prime suspects would be O2 sensor,the air flow sensor or clogged injector. Is your check engine light ON? What are the symptoms?
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  #13  
Old 07-24-2010, 04:28 AM
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M104 Injectors ...

My M104 is fitted with mechanical CSI injection (Bosch KE). Later M104s had the electronic system.

Thus, DIFFERENT INJECTORS.

You need to specify.

In my case, the injectors have injected for nearly 360K Kms and seem to be doing fine (excellent performance and 30 mpg). If you really feel they need to be replaced, the part number is A0000785823 and list price in UK is about 50 each. Discounts are usually available.

You need to replace the seals and no calibration is possible or required.

RayH
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  #14  
Old 07-24-2010, 11:14 AM
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The 93 2.8 is an EFI motor.

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