996 Engine Temp Reading Low

Normal for Ducatis on an open road. The thermostats used open early, so the motor runs cool. Not when you get caught up in traffic though. Then the temp rises rapidly till the fan or fans cut in at just over 100c.

 

They all do that sir, mine barely gets over 65 on the open road although just recently it has been even lower

 

Try opening the throttle

 

Hmmm... Can't help wondering if the ecu is still giving a rich mixture at that temperature

 

80 sounds about right, at least my 916 will run at around 80 degrees (a few more on a hot day, a few less on a cold one) on the open road. Will soon hit high 90's - 100 in traffic though.

Incidentally; I also have an oil temp sensor fitted to the pickup filter bolt and the oil is normally around 8 - 10 degrees cooler than the water...

 

Open road bike water temp for my 999 is 70c.
Oil temp for my 320d is a rock solid 100c once warm.

 

OR, the thermostat starts to open at 75c so the engine is supposed to run at that sort of temp most of the time, it seems cool but that is how it is designed. The accuracy of the gauge is indicative at best and I suspect mine is slow and out calibration due to the inevitable glass crack allowing moisture into the mechanism. I have seen these bikes running at steady indicated temperatures on the open road anything from just over 40 to 85. For the ecu it will match the mixture to the coolant temperature all the time (separate sensor than the gauge) as that is part of the ecu operating strategy, it will not enrich the mixture outside of the set up parameters in the ecu map unless the temp sensor (a thermistor) is out of range.

 

Interesting...
So there is never a cut-off point, after which the mixture remains the same with no further enriching. The ecu just keeps on adjusting the mixture to whatever temperature is recorded by the sensor.
Even so, it would still seem sensible to optimise the engine temp to something that requires minimal enrichment.

Also interesting that there is more than one sensor. My fans switch on sequentially as per spec at 101c and 103c, so it seems the sensors are at least in synch with each other and probably correct. My 999 runs at 70c on the open road, so how can the thermostat not be starting to open until 75c? If that were the case, the engine would be running cool without even having any circulation through the radiator?? Is the oil cooler that effective??

 

Fair point re th/stat operating temp but probably due to a combination of operating variances on temp gauge, th/stat and other sensors. Just because it says " 75 deg" do not take it as being 100% accurate just as you would not take your speedo to be totally accurate at all times.

 

My 996 used to run at 80 unless being thrashed. My 1098 engined 996 runs exactly the same.

 

That rather ties in with my cynical suspicion that Ducati have never bothered to fully develop the cooling system.
My feeling is that they threw something together that warms up quickly, works on track and when being thrashed by test riders through the hills around Bologna. They then checked the fans stop the motor overheating when stationary and declared job done.

 

OR, hope this is not too lengthy but it may help to understand the ‘enrichment’ you referred to is not how the system works with a modern(ish) fuel injection systems. The 1.6 ecu on the 748/9xx maintains 256 set points based on throttle position and engine speed which each have an optimum injector opening time to provide the right quantity of fuel for each set point to get the best burn. When these three control elements are plotted they produce a three dimensional graph which is the ecu ‘map’ that we hear so much about – a plotted map looks a little like geographical relief maps of the countryside with throttle position, engine speed and time on x, y and x axes. The air temperature sensor, barometric pressure sensor and coolant temperature each provide constant trim adjustments to the duration of that fuel pulse at each of the 256 set points. The coolant sensor for example adjusts the mixture/injector open time by as much as +45% at -5c to -3% at 125c. The above is a simplified explanation of the system as there is much more to it than I can write down/understand.

In theory if the bike is properly mapped every one of those set points with all the trim adjustments would produce a perfect air fuel mixture just below 14:1 for all engine operating conditions. When you custom map, that is what you are trying to achieve and the only way to get the map as complete as possible is to spend hours on a dyno with a very accurate exhaust analyser checking as many of the set points as is practical. If you then add the variables for each bike which can include blocked or lower efficiency air filters, dodgy/ dirty sensor plugs, slightly out of calibration sensors, variable fuel pressure and worn throttle/injector components you can see why generic chips sold with an exhaust are at best approximate for any bike and the only way to get it running as well as possible is to custom map it on the bike.

Modern engines tend to not have the traditional cold running enrichment but are more likely to have maps that produce the best burn/lowest emissions throughout the throttle/rev range. This is the reason why vehicles are not fitted with a choke or cold start injector anymore. The cold start button on the 74x/9xx is actually just a lever that opens the throttle butterfly a little and increases the engine speed.

For the thermostat opening at 75 means it will start bleeding coolant through at that temp but it will shut again if the coolant drops below 75 to maintain a steady operating temperature. If the bike has an oil cooler or any airflow it will always have some other cooling effect and it will usually run at a temp close to the thermostat set point. Gauge and thermostat accuracy is indeed questionable and the main thing is that it runs on the open road at a steady and predicable indicated temperature. I think you may be right about the cooling systems but they all seem to operate at a tight range on the open road and the design for Italy at least means it is overspec for road riding in the UK

My 999 also runs at 70c but 68 on colder <10c days. According to the factory manual the thermostat starts to open at 65 +/-2c, first fan comes on at 101c second comes on at 102c, then go off at 100c (first) and 101c (second)

 

Wow, Denzil, please don't apologise for going into detail - always keen to learn.
My current ecu is from an 848 and flashed with a 999 map (courtesy of Chrisw) but with the same PC111 that was attached to the original ecu. The PC111 was set up on a dyno and seems to fuel now just as well as with the original. Do the same 256 points still apply I wonder??
The 65c you mention in your final paragraph makes lots of sense because, like your own 999, mine runs at 70c on a warm day and 68ish when it's cooler.

Still can't help thinking the fuelling would be more efficient it the motor ran 10-20 degrees hotter. If the gauge reads 101c when the first fan starts, that indicates to me that the gauge is pretty accurate and that the sensors are in synch.