Engine sensors... the solution or the problem?

[pan]

So are engine sensors the solution or do they just add to the potential problems with engines? Since buying our boat with twin MAN 800's they have performed perfectly, except for issues with sensors, this wouldn't be problem. but of course they put the ECU into safe mode, reducing engine revs & speed to around 12/15kt. That on short trips wouldn't be a big problem, but on a long voyage could be critical (weather windows etc), never mind the stress they cause, alarms etc.:ambivalence:

These sensors seem to work on the basis of measuring resistance, so I wondered if it would be possible to create a variable resistance gizmo that would plug into the wiring loom where the sensor connects, simulating the restistance of the sensor, so the ECU will not shut down the engine. Obviously this would be a temporary solution, but at least a good 'get me home'

As this forum is packed with extremely knowledgeable technical folk, I wondered if this is feasable?:encouragement:

 

[Croftie]

Coming from an automotive background, possibly anything that measures temperature could be substituted assuming you know what the resistance "window" is and that the problem does not lie in the wiring between the sensor and ECU. For any pressure/vac or rotational sensors then a simple resistance substitution is not going to work as these will probably use hall effect, inductance or similar. The great thing is that modern systems take info from so many sources that if one does go faulty the ECU can often override it and keep the engine going in safe mode. Remember to do a substitution you would need to know which component is faulty.

 

[pan]

From my experience it seems the main culprits are temp sensors, we have had oil temp & fresh water coolant fail (I am told these are common), the MMDS system does identify which sensor, it is obvious that there isn't actually an engine fault as the reading will rapidly bounce randomly from say 85 to 225. The problem is you can do a full re-set, but if the sensor has a fault it will manifest itself pretty soon after.

 

[pmagowan]

It would be a bit of a hack job when the real problem is that the company that sold you the boat did not give you an appropriate way to interogate and override your onboard ecu. In a safety critical system such as a boat engine (moreso than a car) it is important that we can override any arbitrary 'dumb' decision made by the machine. This may be a case of us simply accepting the damage that may be caused to the engine as the least of two evils, shipwreck and associated risk to life being the worst. Until we start to complain to manufacturers and stop buying their products this will continue to happen. Sensors simply give us more information and therefore are a good thing, the problem is the dumb ecu making a potentially dangerous decision and not giving us the power to override it.

 

[Nick_H]

Yep, agreed. We had a generator problem that was traced to a faulty sensor recently, and the boat we are cruising with had the exact same issue 2 days ago.

When mine went, the engineer didnt have the part with him, so he just bypassed the sensor to get the genny running again until he could come back to change it. I guess this wouldnt work if the sensor sends an absolute reading though, rather than just an overheat alarm

 

[Deleted User YDKXO]

So are engine sensors the solution or do they just add to the potential problems with engines?

We have MAN V12 diesels in our boat and probably like your boat, there is a frightening amount of information presented in the MMDS system most of which is provided by sensors and any one of which is capable of putting the engine into limp mode which is very scary. Yup I definitely preferred the days when all you got was engine oil pressure and coolant temp and an alarm if either reading went off piste

Mind you this is only the start of this sensor nonsense. When marine engines have to be fitted with diesel particulate filters and adblue systems, there'll be a whole load of additional sensors to stop the boat

 

[pmagowan]

We have MAN V12 diesels in our boat and probably like your boat, there is a frightening amount of information presented in the MMDS system most of which is provided by sensors and any one of which is capable of putting the engine into limp mode which is very scary. Yup I definitely preferred the days when all you got was engine oil pressure and coolant temp and an alarm if either reading went off piste

Mind you this is only the start of this sensor nonsense. When marine engines have to be fitted with diesel particulate filters and adblue systems, there'll be a whole load of additional sensors to stop the boat

The thing is that it is not the sensors that stop the boat. The sensors give additional information about the health of the engine. This is good. It is the ecu that stops the boat, often because it has responded as programmed because a sensor has read outside predefined parameters. This is a design flaw and should be brought up with the manufacturer. If an ECU is going to potentially put you and your crew at risk by unilaterally deciding to disable your engine then it should be a damn smart ECU. As it is they are simply dumb, programmed badly and do not allow the user to make decisions which may be required to protect the safety of his boat and crew. At the very least there should be a button to override the ECU in case of emergency. More sensible would be a display where the ECU tells you what the fault is, advises you that it thinks the engine should be put into 'limp mode' and then leaves the final decision to you. It is YOUR boat, not the ECU's or the guy who programmed it. YOU should make the big decisions and you should be able to decide to risk the engine to protect the lives of your crew.

 

[Portofino]

Mines not too bad pre common rail circa 2003 .-2876 like PANs 700 hp not 800 ,s
Older tech ?
They just alert ,not shut down .

Currently running with port oil temp sens alarm ,at start up I just delete it .
Symbol says sens alarm ,not actually the thing in this case oil temp too high .

 

[Deleted User YDKXO]

At the very least there should be a button to override the ECU in case of emergency. More sensible would be a display where the ECU tells you what the fault is, advises you that it thinks the engine should be put into 'limp mode' and then leaves the final decision to you. It is YOUR boat, not the ECU's or the guy who programmed it. YOU should make the big decisions and you should be able to decide to risk the engine to protect the lives of your crew.

Sounds sensible but I guess that the engine manufacturer would be delighted to walk away from his warranty if you press that button!

 

[pmagowan]

Sounds sensible but I guess that the engine manufacturer would be delighted to walk away from his warranty if you press that button!

I don't think that would be acceptable. I can understand the engine manufacturer arguing a point if you chose to use the boat week in week out after disengaging engine protection but, the bottom line is, that the engine should be fit for purpose. Part of that means that it needs to function adequately to get you out of a tight spot, even if that means overriding some protection mechanisms. The engine should just work. Your warrantee should only be voided if you are negligent in your managment of your engine and that does not, in my opinion, include overriding an alarm temporarily in order to get out of a tight spot. It would not take them long to lose their reputation if they felt otherwise.

 

[Trundlebug]

At the very least there should be a button to override the ECU in case of emergency. More sensible would be a display where the ECU tells you what the fault is, advises you that it thinks the engine should be put into 'limp mode' and then leaves the final decision to you. It is YOUR boat, not the ECU's or the guy who programmed it. YOU should make the big decisions and you should be able to decide to risk the engine to protect the lives of your crew.

I agree, at least in major part.

The problem at the moment is that if one of the 30 or so sensors fails or develops any kind of fault, a large yellow or red warning light comes on which says "ENGINE MANAGEMENT FAULT" - which means nothing, as it should really say "Temp sensor failure".
Then reading the manual it will say something like "Take to Main Dealer or serious problems could ensue".
Which serves to put the fear of God in anyone.

As you say, the ECU's are dumb. You wouldn't have thought it was beyond the wit of man, and certainly not enginners to just get the ECU to say WHICH of the sensors is faulty, and output that to the dashboard. And it shouldn't be in the form of a fault code either, FFS.
If it knows a code that can easily be converted to a text message in plain English.



I guess they figure it keeps their dealers and engineers in jobs, but really it shouldn't be as hard as it is to decipher what the fault is.
If an ECU knows there's a fault, then it knows why it thinks there's a fault and should tell you as much.

 

[Deleted User YDKXO]

I don't think that would be acceptable. I can understand the engine manufacturer arguing a point if you chose to use the boat week in week out after disengaging engine protection but, the bottom line is, that the engine should be fit for purpose. Part of that means that it needs to function adequately to get you out of a tight spot, even if that means overriding some protection mechanisms. The engine should just work. Your warrantee should only be voided if you are negligent in your managment of your engine and that does not, in my opinion, include overriding an alarm temporarily in order to get out of a tight spot. It would not take them long to lose their reputation if they felt otherwise.

Try telling that to somebody like Caterpillar! We use a lot of their industrial engines in my business and if an alarm goes off and the engine goes into limp mode, it can only be reset by a Cat technician with the right software and if you so much as attempt to reset yourself, the warranty is voided. Don't forget that this kind of stuff provides excellent business for the engine manufacturer's service agent at about £600 a shot:disgust:

 

[pmagowan]

Try telling that to somebody like Caterpillar! We use a lot of their industrial engines in my business and if an alarm goes off and the engine goes into limp mode, it can only be reset by a Cat technician with the right software and if you so much as attempt to reset yourself, the warranty is voided. Don't forget that this kind of stuff provides excellent business for the engine manufacturer's service agent at about £600 a shot:disgust:

That is entirely up to the customer. If we, as customers, refuse to purchase their engines then they will soon change tune. Perhaps we need to get a campaign going. If a boat gets wrecked and some people die as a result of such an ecu related decision I suspect things would start to change pretty sharpish.

Alternatively, surely it is not beyond the wit of man to hack their ecu and come up with 3rd party ECU's which do the same job but give the user the final say. The manufacturer is accountable by both UK and EU law and so can not simply say 'no, warranty is void'. All products must meet statutory requirements such as being free from manufacturing defects, and being fit for purpose. In my opinion, and IANAL, an engine that shuts down every time a minor sensor fails is not fit for purpose in a marine environment.

 

[Deleted User YDKXO]

That is entirely up to the customer. If we, as customers, refuse to purchase their engines then they will soon change tune. Perhaps we need to get a campaign going.

The marine engine market is a pinprick on the back of an elephant to the likes of Cat, Cummins and Volvo compared to their truck and construction machinery markets so I don't suppose they're going to lose much sleep over this. In any case, its the 1st owner that makes the decision on which engines to put in his new boat and he's not likely to be worried about sensor issues since compared to subsequent owners of his new boat, he's the least likely to experience sensor problems. Sensor issues are far more likely to be problems for secondhand boat buyers but those buyers have little or no influence over how sensor problems are processed by the ECU

 

[pmagowan]

The marine engine market is a pinprick on the back of an elephant to the likes of Cat, Cummins and Volvo compared to their truck and construction machinery markets so I don't suppose they're going to lose much sleep over this. In any case, its the 1st owner that makes the decision on which engines to put in his new boat and he's not likely to be worried about sensor issues since compared to subsequent owners of his new boat, he's the least likely to experience sensor problems. Sensor issues are far more likely to be problems for secondhand boat buyers but those buyers have little or no influence over how sensor problems are processed by the ECU

I suspect the engines are out of waranty by then anyway. So, for a second hand boat buyer the thing that might help would be a new 3rd party cpu that simply relays the appropriate information to him, maybe through his MFD, in English. It might give a recommendation or a 'seriousness level' and then let him take control. CAT may not care but the people who make and sell boats may, as should the people that buy them. Unfortunately, as is always the case, if buyers don't give a damn about what they are buying then you can hardly expect the manufacturer or the vendor to care. I don't have the luxury of owning boats with engines of this size but they say the same problem is going to come to the smaller sailing yacht market as engines evolve to meet regulations. Luckily Beta-marine who make my engine have a user installed and serviced waranty so they don't make you jump through expensive hoops just to keep their dealers happy.

 

[davids0865]

Do you guys with newer boats with ECU's not have an OBD port (on board diagnostics) as in modern cars, as when my Jeep throws a code to trigger the Engine Management warning light I plug the reader into the port, it tells me the code number and it's english (ish) translation? The better more expensive reader I now have looks at all 30 modules on board the car, including Transmission, Suspension etc.

On the point of the origonal question about sensors, the Jeeps with a MB diesel have a liking for dropping oil into the swirl flap actuator, a £1000+ dealer job, the forums have found that a 10p 4.4k resistor between the middle two pins fools the ecu, as swirl flaps are purely for emmissions results, most never bother having the actuator repaired, I carry the resistor in the glovebox ready, so , in principle there shouls be ways of bypassing many of the onboard sensors, but you need a techie to advise what the signal is, and that would be cutting of their nose??

 

[pmagowan]

Do you guys with newer boats with ECU's not have an OBD port (on board diagnostics) as in modern cars, as when my Jeep throws a code to trigger the Engine Management warning light I plug the reader into the port, it tells me the code number and it's english (ish) translation? The better more expensive reader I now have looks at all 30 modules on board the car, including Transmission, Suspension etc.

On the point of the origonal question about sensors, the Jeeps with a MB diesel have a liking for dropping oil into the swirl flap actuator, a £1000+ dealer job, the forums have found that a 10p 4.4k resistor between the middle two pins fools the ecu, as swirl flaps are purely for emmissions results, most never bother having the actuator repaired, I carry the resistor in the glovebox ready, so , in principle there shouls be ways of bypassing many of the onboard sensors, but you need a techie to advise what the signal is, and that would be cutting of their nose??

I was sorry to here about your recent demise.

 

[Portofino]

Coming back to MAN MDDS screen ,well the older Vs for those interested I have some pics .
Manuals on the boat ,but from memory there are 3 levels
1 sensor error - the engine functions as normal - only identifies the sensor
2- actual thing error eg water temp 95oC this - goes into limp mode , once outside preprogrammed range .
3 - fault eg overheat 115 oC ( or what ever ?) - stops the engine preventing serious damage .
All three are date/ time stored for future retrieval .
Sorry about pic quality -I was mucking about @ 10 knots pootle -Eventually found optimum = 825 rpm reduced consuption. To 15L/h @ 9 knots -

 

[davids0865]

I was sorry to here about your recent demise.

Thank you Terry is gutted.

 

[pan]

The MAN MMDS system is pretty good at identifying the source of the fault and even gives readings, so that's not really the issue, and you can do a soft reset, the problem is that a faulty sensor will continue to trip the ECU into safe mode (safe for the engine that is), I suppose as been mentioned above the solution would be either intelligent ECU or an override for the operator. It's quite obvious when the sensor is faulty the read out will be all over the place, clearly a constant high reading is likely to cause engine damage and the ECU must enter safe mode or simply lose the engine altogether!

Whilst it would be great to re-programme the ECU, that's not going to happen, so back to my original suggestion, perhaps a homemade variable resistor with the correct values that could be plugged into the sensor connector would provide a temporary solution? Assuming of course you can get the manufacturers resistance parameters for the sensors.

This above is probably just a 'pipe dream', but wonder how many times forumites have experienced simple sensor faults as opposed to actual engine faults, in my case 8 sensor faults to 0 engine faults!! At £200-£300 a pop it's a nice earner for the manufacturer, especially when you can find similar spec sensors at anything from £10 to £70...