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Mercedes Benz E240 WDB2100622B191230 - Does ECU shut down injectors if there is a fault? #

Posted by Paul Howd on May 11, 2009, 8:37 pm

Year of Manufacture *: X reg
Engine Code or Type *: V6
( Optional ) Scanner used: X431

Would I be correct in assuming that this system "Shuts down" injectors if the ECU feels they are faulty.

I am investigating a misfire (rear cylinder, NS bank) and have pined it down to a suspect injector.

I get a switching trace on start up (but with no obvious fuel flow, IE clearly misfires) which flatlines after about 15 seconds.

I will be removing injector for testing on my ASNU in due course so this is just a background ECU statagy quiery for now.

Paul

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Gerard O'Sullivan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2866' width='330' height='300' border=0 style='border:none;'> on May 11, 2009, 9:09 pm, in reply to "Mercedes E240-WDB2100622B191230 ECU Quiry"

Paul
A failing MAF on a Mercedes, particularly a V engine model, will cause a misfire and not set a MAF code.

May I suggest you scope the MAF before going any further.

Gerard

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Paul Howd <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5151' width='330' height='300' border=0 style='border:none;'> on May 11, 2009, 10:03 pm, in reply to "Re: Mercedes E240-WDB2100622B191230 ECU Quiry"
Paul Howd

A misfire involving an injector shutdown on one cylinder only??

(Though I will check out MAF when I get back to vehicle on wednesday)

Cheers

Paul

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Kevin Apps <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on May 11, 2009, 11:07 pm, in reply to "Re: Mercedes E240-WDB2100622B191230 ECU Quiry"
Kevin Apps

Paul
I nearly posted the same as Gerard (but he beat me to it).
And Gerard does know his way around Merc,s and lot,s of other makes

.
Gerard
Hi Mate.
Kev.

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5535' width='330' height='300' border=0 style='border:none;'> on May 12, 2009, 8:08 am, in reply to "Mercedes E240-WDB2100622B191230 ECU Quiry"
Alan Kane - Administrator

Hi Paul,

You are nearly correct. The ECU will shut down one or more cyls bases on its own monitoring of misfires rather that just a faulty injector. The ECU judges the state of misfire based on the time it takes the engine to accelerate from TDC to TDC after firing. Any thing that effects the combustion process will effect the acceleration after the firing stroke so a bad plug will set the same misfire code as an injector/MAF/compression etc.

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Paul Howd <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5151' width='330' height='300' border=0 style='border:none;'> on May 12, 2009, 10:30 am, in reply to "Re: Mercedes E240-WDB2100622B191230 ECU Quiry"
Paul Howd

That makes sence of something.

There were fault codes for misfires on various cylinders, but no indication as to what the cause might be. (ie no specific code for injector fault or anything else)

Will definitly check out MAF before persuing other optios.

Cheers

Paul

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Gerard O'Sullivan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2866' width='330' height='300' border=0 style='border:none;'> on May 12, 2009, 12:03 pm, in reply to "Re: Mercedes E240-WDB2100622B191230 ECU Quiry"
Gerard OSullivan

Paul

"There were fault codes for misfires on various cylinders"

This new information is another pointer towards a failing MAF.

Gerard

Re: Mercedes E240-WDB2100622B191230 ECU Quiry

Posted by Paul Howd <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5151' width='330' height='300' border=0 style='border:none;'> on May 12, 2009, 7:04 pm, in reply to "Re: Mercedes E240-WDB2100622B191230 ECU Quiry"
Paul Howd

I stand berated!

However, in my defence, the car had already been fiddled with by the owner and his freind, So I wasnt too sure about the reliability or relevence of fault codes so i was going back to basics (as it were)

The owner was convinced that it was a coil issue (Mercedes had replaced 5 packs six months ago at HUGE expence and he had tried replacing the sixth one, no doubt pulling various leads off in the process to find the, alledged, dud cylinder)

In my hour "slot" i was able to establish that the coil was OK and that the compressions were OK (the plugs on the affected cylinder had obviously never been "fired". though they seemed a bit oily (though not enough to cause a running problem I would have thought) hence the compression check-just in case!)

I was unable to find a switching trace on the relevent injector but then went on to find that I did get one, but only for the first 15 secs or so, after that the switching stopped and the trace "Flatlined"

During this time, the engin misfired. Sugesting to me, that the injector was not flowing fuel, despite being switched, due to some internal fault.

However, I will let you know how I get on tomorrow

(Picoscope is My Freind!)

Paul

Re: Mercedes E240-Fix (sort of)

Posted by Paul Howd <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5151' width='330' height='300' border=0 style='border:none;'> on May 14, 2009, 8:47 pm, in reply to "Re: Mercedes E240-WDB2100622B191230 ECU Quiry"
Paul Howd

Well, I have discovererd the problem (or the cause anyway)

Its not the MAF, (The MAF may be a bit less enthusiastic than it might be, but it is not the cause of the problem)

It is water in the fuel!

The OSR injector (the one nearest to the bulkhead) is at the low point on the injctor rail. I am guessing that water entering the rail "Pools" at this point producing a misfire on that cylindr. The ECU registers the misfire but can not "see" any reason for it so eventually shuts down the injector on the offending cylinder to protect the engine/cat from possible damage. and generates a non-specific fault code.

How I get the remaining water out of the system remaints to be solved.

But at least I know what I am dealing with now!

(As always, this fault only manifsted itself on the day the owner had decided to trade it in for another car, so he doesnt really want to spend much on it!)

Re: Mercedes E240-Fix (sort of)

Posted by Gerard O'Sullivan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2866' width='330' height='300' border=0 style='border:none;'> on May 14, 2009, 9:02 pm, in reply to "Re: Mercedes E240-Fix (sort of)"

Paul

Well done, take a bow.

I've found Wynns Dry Fuel to be great stuff entirely for dealing with any residual water after you've removed the bulk of it.

It's probably a good idea for you customer to move it on asap.

Gerard

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