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When the throttle off over run cuts fuel on deceleration the trim% goes way up.
I have it set at off 2800rpm and back on at 2700rpm. Problem is when i get back on the throttle its really rich because the trim % sees a lean mixture. Is there anything i can do about the trim % adding so much fuel on throttle off over run. Adaptronic select 440d using wari sometimes Eugene.
Sounds to me like a programming error on the part of Adaptronic. Getting a fix for it probably won't happen so maybe try one or more of the following:
Set a higher minimum load MAP (or TPS) for closed loop. This will turn off the correction under the same conditions that will also engage throttle off overrun.
Decrease the max amount of correction allowed in closed loop or increase the Proportional/integral values so it reacts quicker.
Lastly, just don't use throttle off overrun, it's really only for fuel mileage, and it's probably not safe if you are premixing because when it engages you've got no lubrication.
Sounds to me like a programming error on the part of Adaptronic. Getting a fix for it probably won't happen so maybe try one or more of the following:
Set a higher minimum load MAP (or TPS) for closed loop. This will turn off the correction under the same conditions that will also engage throttle off overrun.
Decrease the max amount of correction allowed in closed loop or increase the Proportional/integral values so it reacts quicker.
Lastly, just don't use throttle off overrun, it's really only for fuel mileage, and it's probably not safe if you are premixing because when it engages you've got no lubrication.
I'll look at what the settings are. Oil metering pump only operates when you hit the accelerator. So on deceleration the metering pump is not adding oil to the fuel. I dont have a metering pump i premix. But not to worried about lack of lubrication on decel.
It always pumps oil, just more on throttle, less off throttle. It's a very small amount, but without any fuel or oil, if you were cruising down a long downhill just using engine braking, that could be a long period of spinning rotors without any sort of lubrication.
Good tips listed there. I'll have to check my logs to see if I'm seeing the same effect on mine. Regarding adaptronic's responsiveness, they're actually really responsive to bugs. I emailed them about getting the low oil pressure safety triggered when first starting the engine because pressure hadn't built up for a second or 2 and they had a new firmware/software build out within a couple days that had a time delay adjustment.
It always pumps oil, just more on throttle, less off throttle. It's a very small amount, but without any fuel or oil, if you were cruising down a long downhill just using engine braking, that could be a long period of spinning rotors without any sort of lubrication.
Just so you know premix leaves a film on the housings one of the many reasons it's superior to OMP. If anything if it's a rich spike like my car I say it squirts a bit of premix/fuel before you have none, my car spikes rich for a second I'm not that worried about it.
I'm aware of how both premixing and the OMP function when it comes to lubrication and I wouldn't say either is "superior" to the other for all driving conditions. It depends on your typical running conditions, but it's been debated to death and not really worth getting into again.
I just came off the top of Mount Washington this weekend, a 6,000ft mountain road descent. That's the type of drive I would not want to take without an OMP unless I disabled overrun. I'm talking about 15 minutes of descending a mountain road with no throttle, just engine braking and occasional actual braking. The OMP in my setup keeps the engine internals oiled even when the injectors are turned off. Premix will probably keep the housings lubricated for a while...but I don't think it will hold up to several minutes of the engine spinning at 4,000RPM with no re-application.
Back to Holdfast's original question. I just looked at my recent logs. I see a trim spike when overrun disengages, however it doesn't result in a rich spike on my AFR log, I see about 1/2 second of +10 trim (the max allowed in closed loop) that eventually settles down as the engine catches and the AFRs settle. This is for a map (not tps) based tune with throttle body injectors, so it takes a moment for the fuel to coat the manifold after the injectors turn back on. Note that this was light application of throttle while cruising at 40 mph @ 2500 RPM (4th gear). Pressing the throttle in this case did not engage the asynch accelerator pump.
Just so you know premix leaves a film on the housings one of the many reasons it's superior to OMP. If anything if it's a rich spike like my car I say it squirts a bit of premix/fuel before you have none, my car spikes rich for a second I'm not that worried about it.
As chuyler pointed out, there are many pros and cons to both types of setups which are well documented on this and other forums. However, I think the reason you think premix is superior to OMP is plainly incorrect.
If it is 2 stroke oil and it is suspended in the atomised air fuel mixture, a greater proportion of it is likely to be burned away rather than deposited on the housings. Conversely, the OMP system dribbles oil directly onto the centre of the apex seal where heat (and friction) is highest. It remains an oil, is not suspended in the AF mixture and is less likely to be burned away, but rather dispersed across the apex seal, with a concentration around the centre of the apex seal. In both systems, unburnt fuel will wash the oil away from where it is needed to a degree (counteracting the rich spike before overrun). But, of the 2 systems, the OMP is more likely to leave a film on the housings - this is precisely why Mazda moved the oil check valves to the rotor housings and used them exclusively in that location on the 13B-REW onwards. On the flipside, this is the same reason why OMP could lead to additional carbon buildup if there is more partial combustion of the oil.
04-20-19, 02:17 AM
