Injector not working?

ZISLANDER

MEMBER
2008 MERCEDES BENZ VITO
2.2L
4 CYL
TURBO
2WD
MANUAL
160,000 MILES

Dear Pros,

I am trying to diagnose what is going on with my Mercedes Viano 2.2. L from 2008 with 160'000km. (WDF36981313464707).
All injectors had been checked, cleaned and re-installed a few months back. For info also my battery is new.

The symptoms are white smoke that smells like diesel no matter if the engine is hot or cold, poor mileage and a shaky engine.

I started by unplugging the injector connectors one after another and I noticed no change when pulling out cylinder 1. Funny enough, the car stopped smoking with the injector 1 unplugged. With it plugged back it shortly started smoking again.
My OBD2 scanner gives me fault ECM 2268 component N14/3 Glow output stage does not work properly, this with 4 new glow plugs freshly installed. The car starts well so it tells me the glow plugs should be working fine.

Next, I tested the continuity of the wiring between the ECM and the injectors which is all okay.
With a multimeter, I am unable to read any resistance in Ohms across the any injector pins. I get about 2.4V on the power wire to the injectors.

Could my ECU be shutting off one cylinder due to a sensor fault or is it the obvious; a faulty injector sometimes stuck open, sometimes stuck closed?

Thank you in advance for your help

PS: I do not have an amp meter or oscilloscope.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,539 POSTS

It sounds like you have low compression in one cylinder which will cause the fuel not to be burnt and white smoke to be produced. I would do a complete compression test on the engine to make sure it is okay or not.

This guide can help:

https://www.2carpros.com/articles/how-to-test-engine-compression

and

https://www.2carpros.com/articles/symptoms-of-low-compression

and

https://www.2carpros.com/articles/the-reasons-for-low-compression

Please go over these guides and report back.

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Saturday, April 15th, 2023 AT 10:22 AM

ZISLANDER

MEMBER
3 POSTS

My scanner doesn't have the misfire function and since I don't have all the tools necessary to check the reminder of the parameters I went for a few basic tests.
The compression like you mentioned could certainly be the issue which would require testing.

I tested the injectors with a Noid light and all 4 receive signal for a few seconds before the ECU shut them off. The Bosch injectors are of piezo type. It could be that the injectors are electrically sound but mechanically the mechanism get stuck open or closed sometimes. The doesn't give me a code for injectors because it is good at detecting electrical faults but not so much mechanical ones.
The glow plug stage code could just be random with the engine running poorly.

Anyway, I am going to install a brand-new injector on cylinder 1 this week and will let you know if that solves it.

Thanks, and regards, E

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Saturday, April 29th, 2023 AT 3:04 AM

KEN L

MASTER CERTIFIED MECHANIC
47,539 POSTS

That would be great, I would check the compression as well.

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Sunday, April 30th, 2023 AT 10:01 AM

ZISLANDER

MEMBER
3 POSTS

Dear Pros,
Replacing the injector in cylinder number 1 for a new one did fix the issue. After installing it and coding it the car kept smoking a bit for a while which almost led me to believe that the problem persisted. However, after a few minutes the last residue of fuel in the exhaust burnt off and now it runs smoothly without any white smoke.

The diagnosis without advanced tool can be tricky. Also, if changing the injector make sure the injector seat is cleaned, the injector screw and copper ring are new. 7nm torque for the screw + twice 90° turn for final tightening.

All the best and thank you for the support.

Emmanuel

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Wednesday, May 17th, 2023 AT 7:41 AM

KEN L