CR Probs.

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Merlyn
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CR Probs.

Postby Merlyn » Sat Dec 17, 2016 8:59 am

8) Went out to a 550bhp/shp ship genset with management problems last week.
MIL light came on on control panel.
FCR system and 5 fault codes stored.
Erased codes and ran up the plant.
No FC reappeared so allowed engine to run for 6 hours, nothing reappeared FC wise so left the ship.
Next day MIL light came on again.
Went back to the job.
FCR system, nothing stored.
Started oscilloscoping system, all sensors and actuators and associating wiring etc and feedback situations, no faults found.
Thinking in great depth about the problem I noted that this exhaust system was fitted with a Catylistic Converter System with both an upstream and downstream O2 ( Lamda sensor ) whose downstream sensor was on top limits but not enough to trigger the necessary FC. Incidentally this is a four wire installation.
Different from a two or three one.
Scoping the sensor and observing the scope pattern against our library stored ideal readings for this engine model no etc I noticed pattern display differences on the voltage side throught the temp. ranges.
Removing the sensor with difficulty ( a lot of them grow/ weld themselves in there, don't rip the insert out ) and measuring the correct resistance it revealed it was well within limits again throught the temp. ranges.

So we know that the only item near to the manufactures listed limits on the engine is the downstream O2 sensor which clearly when scoped displays an " up on the mark " situation when running under load but when removed from the engine and tested for different temperatures for different resistances appears to be within limits.
What you going to do?
How are you going to handle this re the owners?
If you replace the O2 sensor and it doesn't cure the problem this could be your Xmas present to the owners as if you don't handle this situation correctly it's possibly down to you with accusations/thoughts of incorrect diagnosis flying around.
Just to add to the problem remember that this is an intermittent fault and that by disturbing something else you can put off the reoccurance of this defect and it might run on for several days before the MIL light reappears.
In other words we do not want a ( as we call it ) " since you situation " to occur.
So the fault would appear to lie in the downstream O2 sensor but when removed a series of static bench tests says it's ok.
So is it down to the sensor or what? Would you renew the sensor or not?
What you gonna tell the owners?
How are you going to handle it?
What you gonna do?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: CR Probs.

Postby JK » Sat Dec 17, 2016 11:19 am

We've run into impedance changes in wiring caused by temperature changes that caused erroneous signals.

Revolver
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Re: CR Probs.

Postby Revolver » Sat Dec 17, 2016 1:45 pm

Frigg around with the sensor some, almost sounds kind of like what happened in my last SUV haha. The heater circuit in the sensor ended up cooking and then eventually opened the circuit.

Is it supposed to be a 4-wire config?
Any work history recorded?

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JollyJack
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Re: CR Probs.

Postby JollyJack » Sat Dec 17, 2016 10:35 pm

Confirms my opinion of electronic controls, very reliable, it WILL fail.
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Merlyn
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Re: CR Probs.

Postby Merlyn » Sun Dec 18, 2016 12:44 am

Different temps on some sensors = different ohms readings, hopefully within makers specs.
Your heater sensor, did you mean the glow plug circuit one R ?
Some installations have a four wire loom but a three wire sensor fitted.
Redundant jobby.
No, no work history concerning this defect save for old FC's stored in its pea sided brain from old wounds which when erased did not return.
For example if it's a 24 v system every slavestart it ever had is logged.

Yes JJ I agree with you 100% but the million dollar question remains.
The diagnostic machine says the O2 sensor is on top limits so would you replace it?

The MIL light is the light that comes on when you get wound up JK.
Usually on the forehead, glows red.
Management Indicator Light.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: CR Probs.

Postby JK » Sun Dec 18, 2016 5:03 am

The MIL light is the light that comes on when you get wound up JK.
Usually on the forehead, glows red.
Management Indicator Light



Ah, that popping vein on the forehead, usually caused by trying to restrain a cutting remark to UM.


I've spent too many years buying, installing and wrangling suppliers. My in-depth knowledge is pathetic.
I've gone from knowing quite a bit about some things , to a little about a lot of things and well on to nothing about everything. This is evidenced by my inability to scan a bag of nuts at the grocery store yesterday. But that's a whole ' nother story.

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Merlyn
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Re: CR Probs.

Postby Merlyn » Sun Dec 18, 2016 5:33 am

Metric or Imperial nuts?
Maybe you need to dig out your old thread gauges, you know, 55 degrees for Whitworth/BSF and 60 degrees for that foreign stuff, Metric.
That way I figure you won't go home with the wrong nuts in the future.
Just a thought.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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D Winsor
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Re: CR Probs.

Postby D Winsor » Sun Dec 18, 2016 5:40 am

Where the sensors seem to be within proper parameters when tested, I'd probably start checking pinch points in the wiring harnesses on the engine and control box glands for bad or cracked insulation or damaged shielding, loose or broken terminal strip connections inside the control panel and external junction boxes and corrosion on circuit board connections.
I would also check for changes in air flow around the engine from the ventilation system, any kind of evidence of water or moisture (condensate) around connections and the CPU cooling fans.
Most control systems like this use a 24V DC power supply with a battery backup and sometimes faults in the power supply can cause false or intermittent faults elsewhere that are difficult to trace. I would therefore check the DC power supply to the unit starting with the batteries and then the charging unit itself. It is possible that there may be a fault in the charging circuit (diodes, filter capacitors or switching relays) and the charging unit is sending a high voltage spike through the system, or there is a major DC voltage drop when switching to the batteries, possibly when the charger goes through a self test cycle. It is also possible the control circuit is sensing a spike, through the ground connection from a faulty power supply on another piece of equipment. On one ship I was on any kind of electronic power supply that was plugged into the ship's main power supply including the capacitor starters for high tension lights would suddenly catch fire and burn out. The fault was traced back broken diode insulators in the DC Power Supply and Static Inverter for one of the ship's radars that was sending high voltage spikes to ground every time the radar was turned on. If the exact time of day is known when the fault occurs it could help determine if the charging circuit or the power supply for another piece of equipment could be causing the problem.
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

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Re: CR Probs.

Postby Revolver » Sun Dec 18, 2016 8:11 am

Well by, just say you measurements on that sensor were no good. Replace it, you know you have a good one, problem gone A-ok, problem comes back tell them it must be a combination of the sensor and something else. ;)

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Big Pete
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Re: CR Probs.

Postby Big Pete » Mon Dec 19, 2016 4:31 am

As Revolver says, it is on its limits, change it and then that is one possibility resolved, if it is on its limits it is unlikely to get better, unless you want to go back next week to change it and boost that pension a bit more so you have some cash to Bunker your little yacht.
If the fault comes back then there are other faults on the system, a lot of good suggestions above.

I like the one about looking for common factors when the problem occurs, time of day load on the engine, other auxiliaries running etc, this might be one of Sherlock Holmes's 3 pipe problems.

Good Luck,

BP.
It is always better to ask a stupid question than to do a stupid thing.

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Merlyn
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Re: CR Probs

Postby Merlyn » Sun Jan 15, 2017 2:14 am

Replacing the downstream Lambda on this particular job would ( although it's on top limits ) clearly show that when the engine is run up it still shows the sensor to be on top limits even though it's a brand new Bosch one ( and not a Woolsworth one ) and the original fault to still be present.
In other words it's exactly the same.
Made lots of mistakes like this back in the eighties when CR management systems really came into play down our way and renewed actuators and sensors unnecessarily because of one reason.
They were the SYMPTON and NOT the CAUSE.
As the Lambda sensor tests ok throught different temp ranges on the bench perhaps ( as I have been caught out before ) it's better to look elsewhere for the CAUSE and not as displayed, the SYMPTON.
The next step?
Enter the Wiggle test.
Unclip all wiring from the ECU feeding the downstream Lambda sensor and with another person checking the multiplug feeding the sensor observe any voltage changes to the heater circuits etc ( if fitted with same ) when wiggling the loom.
If you are lucky enough for it to show up straight away then slit open the loom exposing the four wires entering the main loom sometimes, in this case locate the fault being a chaffed/ working wire, make up and solder/let in new sections as necessary. This next step can expose the sensor loom wiring disappearing into the main loom thereby revealing fifty plus wires so this is not for the faint hearted nor the shaky hand mob.
Plus if the fault is not apparent it could be construed by some that many hours have been wasted but anyone worth his salt knows that diagnostics is the art of elimination throught all and any testing.
All wiring now exposed on with the next stage of elimination.


Check very carefully for further damaged/burnt wiring tracking over etc etc.


Conduct further tests as necessary on other wiring.
Check all spades/connections for continuity and security
(Well done to Dave Winsor here at this point )
Should all be ok at this point then we have to look at the ECU as this output signals are ECU controlled.
I see we now have five wired oxy sensors coming out, it all seems to change continually all the time
Yet again this particular problem vividly illustrates that what has now with CR defects become relatively common place and that saying we invented over here comes once again to the forefront.
Cause not symptoms ruling applies once again.
It's the cause we are looking for and although we may well have to get that from the symptom we cannot ( as we did back in the eighties ) go about renewing components willy nilly on the basis of " well the FCR clearly stated that the part in question was not working correctly."
Been on loads of jobs whereby the ECU and other parts were replaced by others quite unnecessarily so, although they were the symptom they were not the cause.
Injectors is a favourite one that springs to mind.
" No 3 injector faulty " says the FCR so in goes a new one and when it starts missing again and it's re read what does it say?
The FCR states exactly the same.
" No 3 injector faulty "
The FCR tool cops the blame when in actual effect it's a loom problem causing the misfire all along or the wrong signal being received from the ECU.
Although it clearly said no3 injector faulty, yes it is but only because it's not being fed with the right signal.
So by replacing the " faulty " injector the FCR will be telling you it's still faulty.
Just to confuse things even further over the years I have been caught out and wasted much time and thereby money with faulty new parts thereby really confusing the issue.
Faulty new injectors for example, we have allways had the kit on hand to test the mechanical injectors throught the years but the new common rail injectors present a different method of testing completely.
Utilising the original injector testing machines and a special modification re piping together with an electrical " break out " box we can test the CR injectors but can perform only a " function test " on them but cannot write a programme for them which of course the engine ECU does.
Another thing that has happened throught history is you remove the new part, send it back to the makers who test it, say nothing wrong with it, you look everywhere else on the engine, refit the " nothing wrong with it " part and hey presto, guess what?
It's up and running on all cyl.
Personally I hate people / firms who do this just to cover their own ass and smokescreen the true situation.
Another one that springs to mind is the code thrown up telling you each and every injector is faulty.
Some manufactures have built into the software a TTG factor (time to go ) which means that when the engine has competed the several thousand hours logged it will throw up the fault code telling you a complete injector change is necessary despite the fact the engine runs sweet as a nut.
Another new learning curve here to be learnt.
As on this installation the injectors have to be programmed to the ECU when fitting a new set but I have learnt that you can cheat the ECU by re programming the original injectors and the ECU thinks it's got a new set fitted.
Off it runs for many many more hours but to cover your ass and avoid any " since you jobs situation " it is imperative to keep the owners/operators of all stages of all work being conducted and keep the door open re further different faults which may well now appear although originally they were not present on the original inspection. ( no " since you " remarks wanted nor apply here )
This particular intermittent fault was caused by bruised wiring tracking over possibly accelerated by temp. changes ( well done BP here ) and not visible to the naked eye whereby the wiring had not been centralised correctly during the original installation some years earlier when clamped up to the bracketed clamping arrangements.
So top marks to Dave Winsor here , could be an opening for him over here should he ever up anchor but looking up his lat./long. I figure that he would not be able to go home for dinner and as such it's back to the heavy weather gear for him.
And JJ?
See what you are missing Eh?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JollyJack
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Re: CR Probs.

Postby JollyJack » Sun Jan 15, 2017 11:37 pm

I don't know about CR problems, but I do have a CPP problem. When I look down, I can't C my PP>
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Merlyn
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Re: CR Probs.

Postby Merlyn » Mon Jan 16, 2017 12:24 am

Crank Position Problem?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: CR Probs.

Postby JK » Mon Jan 16, 2017 5:20 am

Hehehe, JJ. Bulbous bulb needs re-engineering, but I'll bet you're as streamline as a seal.

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Merlyn
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Re: CR Probs.

Postby Merlyn » Tue Jan 17, 2017 8:47 am

If you subscribe to JK's theory be very worried JJ.
Although Bulbous Bows were all the rage they are now cutting them off re reduced speed steaming coming to the forefront concerning a lot of the Container shipping lines.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.


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