T1N Fuel Injectors Information

jackbombay said:

I have some smoke at start up and a slight miss at idle, ...

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One of my injectors was replaced to fix the same issue for me, but I don't know what technology was used to identify it since it was replaced by the dealer under warranty. Although Dennis pooh-poohs it, I think the "shade tree" leak-off test (cranking rpms) would find it.

Here are the injector test results,

talkinghorse43 said:

One of my injectors was replaced to fix the same issue for me, but I don't know what technology was used to identify it since it was replaced by the dealer under warranty. Although Dennis pooh-poohs it, I think the "shade tree" leak-off test (cranking rpms) would find it.

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I don't poo poo it as you write!
Its simply a rudimentary test .
The only way you can effectively judge injector operation is to get them tested on a machine as I have indicated.

A few weeks ago I spent three hours at my local Bosch injection supplier going over failure examples and re-hab of injectors in their establishment. Not just on Sprinters, but Cummins and GMC Duramax.
One thing that struck me most was the wear caused by water and contaminated fuel that had been passed by high injection pressures over the bleed tube and ball/seat arrangement.

Even looking at attempts by Bosch to chrome plate these very fine components in their replacement injectors seems in some cases had little effect. Primary concern is that of reducing failure due to poor handling, questionable repair techniques and use of bad contaminated fuel/filtration.

I would conclude that the biggest impediment to accepting this fact is one major issue and one alone & that is the cost to maintain or put right the underlying problem.
Most so my customers don't want to go there !
But if you want it to run right them sometimes the mantra had to be fix it right first time!
Dennis
Mechanic

lindenengineering said:

I don't poo poo it as you write!
Its simply a rudimentary test .

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Bosch doesn't present it as a rudimentary test, but a useful screening test (below from their brochure attached to an earlier post):
"To be able to repair a vehicle quickly
and cost effectively, the fault must first
be localized to a particular subsystem by
a process of elimination. Mechanical and
hydraulic faults are often analyzed first.
A variety of testers are deployed for the
purpose, including the back flow meter,
specially designed for testing of
Common-Rail injectors.
Back flow leak tester enables return flow
measurement on Common Rail injectors
(including Piezo injectors) on passenger
cars and commercial vehicle systems.
Adapters allow connection of many
injectors to the device."
Based on my limited experience and the above, it seems to me that if there are operability problems (i.e., smoke, miss, etc.) that can't be traced to another source, one of the first injector tests would be the leak-off test(s) to identify the problem injector and then the testing you propose to pinpoint the problem. Or, do you advocate a prophylactic regimen of pulling injectors (in the absence of apparent issues) and subsequent detailed testing?

PS - Seems there might be more than 1 leak-off test procedure - do you have procedures for leak-off tests at other than cranking rpms?

jackbombay said:

Here are the injector test results,

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I have attached a recent presentation by Bosch that helps make sense of your injector test results. A quick scan of the data you shared (post 22) tells me that the failed injectors didn't miss the mark by much.

talkinghorse43 said:

A quick scan of the data you shared (post 22) tells me that the failed injectors didn't miss the mark by much.

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Interesting, before I pulled them thevan was smoking quite a lot, 10 miles on the cruise control at 55 mph, slow to 335 through a small town, then 3/4 throttle to accelerate back up to 55 on the other side of the small town would leave an embarrassingly large cloud of rather dense black smoke. The exhaust stank at idle and was a bit smoky till the van was all the way warmned up.

The new injectors made a massive difference with regards to smoke reduction.

I'll check the link now, but maybe none of those tests address spray pattern/fuel atomization so while an injector can test almost good it will still make a lot of smoke due to a worn/bad injector nozzle?

talkinghorse43 said:

...

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When you had rust/high pressure rail damage due to water in fuel did you also replace the high pressure pump? Or just the rail and rebuilt injectors?

I'm wondering how far I should go to ensure I don't end up with more injector issues from the same event.

jackbombay said:

When you had rust/high pressure rail damage due to water in fuel did you also replace the high pressure pump? Or just the rail and rebuilt injectors?

I'm wondering how far I should go to ensure I don't end up with more injector issues from the same event.

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I didn't have the dealer do anything with the pump (rebuilt unit from the good Doktor, installed before the water event) or the injectors (I haven't done anything either). They did replace the plastic suction line from the filter to the low pressure pump (I was sitting on one I purchased years ago because the filter end fitting was dodgy). They may have cleaned the piping (internally) on the high pressure side, but I didn't instruct them to do so (the intake manifold recall was wrapped into this repair, so many things could have been done - they did replace the coolant, which is not in the recall scope of work). I wrote earlier that I had a miss at idle for some time after the repair, but I remember now that miss was only when cold (initial start) and disappeared after warming up. Doesn't miss at all presently.
Your issue seems to be longstanding, so my experience (~3 winter months elapsed from water contamination to repair) may not be the best guide.

For anyone with a no start situation due to low fuel pressure because of one or more leaking injectors, the leak off test is invaluable.
On the other hand, there are many things that the leak off test does not tell you about an injector. That's where the DAD, other higher end scanners can tell you some more things and finally the actual injector tester that Dennis is talking about for a complete picture.
I don't think we should make more of the test than is due, nor should we be quick to dismiss it. It is simple. It is rudimentary. It is also very good at what it does. It's not good for much else.

Type2Teach said:

It is also very good at what it does. It's not good for much else.

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Yes it is!


It let me know my cam position sensor was likely on the way out as opposed to my injectors returning too much fuel to the tank.

Actually, the leak off test just told you it -wasn't- the injectors that were causing your no start issue. It didn't tell you that is was the cam sensor. You just used the info from the leak off test to know to look at other components of the starting requirements. Fuel pressure loss elsewhere, cam sensor, crank sensor, etc...

Type2Teach said:

Actually, the leak off test just told you it -wasn't- the injectors that were causing your no start issue. It didn't tell you that is was the cam sensor. You just used the info from the leak off test to know to look at other components of the starting requirements. Fuel pressure loss elsewhere, cam sensor, crank sensor, etc...

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Very true, I suspected both, and the cam sensor was cheap enough that I just bought it and that was indeed my problem.

Type2Teach said:

For anyone with a no start situation due to low fuel pressure because of one or more leaking injectors, the leak off test is invaluable.
On the other hand, there are many things that the leak off test does not tell you about an injector.

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I didn't have a no start situation, but a miss at idle - twice. The leak-off test found both of those injectors and new injectors fixed the issue. So, the "rudimentary" test you described in your thread can be more useful than you think.

No return is bad. You have to wonder where that fuel is going. The injectors rely on so much return to cool their solenoids, our recent visit to Williams Diesel in Ocala shed a lot of light on the common rail. Too much return is not good either as it starts to rob rail pressure from other injectors.
These are super high pressure injectors with components that move less than 10 microns in some cases. It's not enough to verify you have a shot. If any injectors are stuck open, this will ruin the motor fast.

The improper coding won't make the motor not run. The coding is for injector mass adjustment. Basically the coding is assigned based on how an injector performs at multiple points along the fuel curve, it's offsets to adjust how long the injector should stay open for. We are talking about microsecond level adjustment.

The injectors can fail at multiple points but be okay at idle.

Lindenengineering, I wish I had read this before replacing the nozzles in my injectors! I thought keeping them in the original location would perhaps be safe, but apparently not, ha! That said, the engine actually starts and runs, drives slowly with low power. I *think* I reassembled them all correctly...so at this point can I send them out for testing and recalibration? Who's the go-to place if so? The Bosch injector shop here in Oregon laughed and said they can sell me reman ones for $333 each. Anyone have experience with the reman injectors sprintersupplier sells for $175?
Lastly, a European supplier I buy a lot of parts from lists several choices for the T1N OM612. What p/n am I searching for?

The part number for the 2002 to 2003 engine is 6120700487/87.
Trade price starts at about $192 each and retails around $345,60 a pop, here in the US,
Dennis

Trade price = what a repair shop can buy for? What vendors are recommended?
I've inquired to sprintersupplier to find out who rebuilds the ones they sell.
It seems I should be able to have mine calibrated and coded though, right?

A short answer is NOT necessarily.
In short the internal port drillings inside the injector body get eroded and using a microscope they look like the Grand Canyon. When eroded to excess they affect the vital injection control of the internal ball & set operation of the injector.
For that reason your injectors might not pass muster and demand total replacement .
Dennis

I'd like to hear feedback on what sources are worth buying from. The pricing is all over the map from $175 to $400. However there are some new Bosch in EU for $234.

I would assume NEW Bosch injectors will have the IQA etched into the injector bodies?
Thanks for your guidance, this is my first time dealing with Mercedes CR injectors, all of my past work has been in the VW world.