Dead or dying maf? there's another option!
I know there's already a thread on maf replacements etc, but I don't want to hijack it.
It's something I've been working on since my own mass air flow sensor died, it's actually taken some time (months) to develop but i'm virtually ready to add it to our lineup and will be my first step into the world of 75 tuning.
It's essentially a mafless remap, but it does things a little differently from what research i've been able to conduct from the norm.
The role of the maf sensor as we know, is to give the ecu a means to control EGR operation, but also to be able to provide a reasonable value representing the availability of oxygen in the cylinder, which allows us to limit the fuel delivered so as to reduce soot formation. This has a drastic impact on a vehicle's performance as when you put your foot down, what torque you're requesting with your foot may or may not be delivered, and one of the conditional values on this being the mass air flow measured. So when a sensor fails, you can sometimes get an artificially low reading, meaning you lose performance. Worse still, if it fails in the wrong way it can also cause the egr to open unnecessarily, which causes a complete loss in performance! Which can be sudden and a bit unnerving.
Most ecu's though have support for multiple ways of fuelling, for example some (like the rover sdi's) use air pressure to meter air availability, some use maf sensors (like the 75) and newer cars broadly use lambda sensors now.
The good news is, after a bit of testing, the rover 75 actually supports fueling by manifold or boost pressure. This has to be enabled by a switch in the software, but it means you can say goodbye to the maf sensor forever.
This is a bit different to how some mafless remaps work, because a lot of these cause the ecu to think the maf is not present, and it instead 'assumes' from the engine speed etc what the maf reading would normally be, which as has been commented on in the past, isn't entirely as accurate even though it releives a lot of the symptoms.
By adjusting the mapping to fuel on on air pressure instead (a feature that is included in the rover 75 ecu's - just disabled by default) you can once again create realistic fuelling for the whole rpm and load range, using accurate sensor feedback (for example the air pressure is temperature compensated) and is quite ideal for both standard cars, and cars that have a performance remap on them. I've used my own 75 tourer as a test subject for the development of this mapping technique and i've tried it with both a fairly standard level of tune with the maf sensor deleted, and with a performance tune. In both cases i've had a fairly good result (the 115 map honestly is slow on a tourer though, it has to be said!) but with my performance map on it, it absolutely flies as well. The car runs quite clean, though I've got a very agressive map on it at the minute which hazes a little. The fantastic thing is though with this mapping technique I can fine tune it with precision by logging boost against rpm so I know where exactly in the map to adjust the fueling if it's too smokey, or increase fuelling if it doesn't smoke and we want a little more responsiveness.
The fantastic thing about this is, even though the maf sensor goes in the bin, we retain full control over smoke and fuel quantities etc with a large high precision fueling map. I've done hours of testing with this, i've put hard cut fuel restrictions in based on both engine speed and boost pressure for example and experienced the 'brick wall' affect when i've exceeded this boundaries on the road - real world tests that tell us that mass air flow is being disregarded in favor for boost pressure.
I've just been chatting to some tuners and most have been surprised that this is possible on this ecu - so I just want to say, it is possible, and theoretically it does mean people may not ever have to put out on a maf sensor again. This does not necessarily tie people to a map, though the patch is applied using the same techniques.
The location of the switches do vary between software versions, so I've been collecting readouts of 75 ecu's, but the actual implementation of the software patch is fairly uniform. I don't know if it's worth investing much time into getting a solution available for all 75 and ZT revisions but if there's any demand for such a service I'm willing to look into it.
This has been a long project for me, I'm a bit stubborn about solving these problems so it's nice to be able to post up and say 'weve got rid of the bugger!' haha. It's been work because we've had to literally reverse engineer parts of the software, but we got there.
The 75+ZT diesel community has options now, anyway!
It's something I've been working on since my own mass air flow sensor died, it's actually taken some time (months) to develop but i'm virtually ready to add it to our lineup and will be my first step into the world of 75 tuning.
It's essentially a mafless remap, but it does things a little differently from what research i've been able to conduct from the norm.
The role of the maf sensor as we know, is to give the ecu a means to control EGR operation, but also to be able to provide a reasonable value representing the availability of oxygen in the cylinder, which allows us to limit the fuel delivered so as to reduce soot formation. This has a drastic impact on a vehicle's performance as when you put your foot down, what torque you're requesting with your foot may or may not be delivered, and one of the conditional values on this being the mass air flow measured. So when a sensor fails, you can sometimes get an artificially low reading, meaning you lose performance. Worse still, if it fails in the wrong way it can also cause the egr to open unnecessarily, which causes a complete loss in performance! Which can be sudden and a bit unnerving.
Most ecu's though have support for multiple ways of fuelling, for example some (like the rover sdi's) use air pressure to meter air availability, some use maf sensors (like the 75) and newer cars broadly use lambda sensors now.
The good news is, after a bit of testing, the rover 75 actually supports fueling by manifold or boost pressure. This has to be enabled by a switch in the software, but it means you can say goodbye to the maf sensor forever.
This is a bit different to how some mafless remaps work, because a lot of these cause the ecu to think the maf is not present, and it instead 'assumes' from the engine speed etc what the maf reading would normally be, which as has been commented on in the past, isn't entirely as accurate even though it releives a lot of the symptoms.
By adjusting the mapping to fuel on on air pressure instead (a feature that is included in the rover 75 ecu's - just disabled by default) you can once again create realistic fuelling for the whole rpm and load range, using accurate sensor feedback (for example the air pressure is temperature compensated) and is quite ideal for both standard cars, and cars that have a performance remap on them. I've used my own 75 tourer as a test subject for the development of this mapping technique and i've tried it with both a fairly standard level of tune with the maf sensor deleted, and with a performance tune. In both cases i've had a fairly good result (the 115 map honestly is slow on a tourer though, it has to be said!) but with my performance map on it, it absolutely flies as well. The car runs quite clean, though I've got a very agressive map on it at the minute which hazes a little. The fantastic thing is though with this mapping technique I can fine tune it with precision by logging boost against rpm so I know where exactly in the map to adjust the fueling if it's too smokey, or increase fuelling if it doesn't smoke and we want a little more responsiveness.
The fantastic thing about this is, even though the maf sensor goes in the bin, we retain full control over smoke and fuel quantities etc with a large high precision fueling map. I've done hours of testing with this, i've put hard cut fuel restrictions in based on both engine speed and boost pressure for example and experienced the 'brick wall' affect when i've exceeded this boundaries on the road - real world tests that tell us that mass air flow is being disregarded in favor for boost pressure.
I've just been chatting to some tuners and most have been surprised that this is possible on this ecu - so I just want to say, it is possible, and theoretically it does mean people may not ever have to put out on a maf sensor again. This does not necessarily tie people to a map, though the patch is applied using the same techniques.
The location of the switches do vary between software versions, so I've been collecting readouts of 75 ecu's, but the actual implementation of the software patch is fairly uniform. I don't know if it's worth investing much time into getting a solution available for all 75 and ZT revisions but if there's any demand for such a service I'm willing to look into it.
This has been a long project for me, I'm a bit stubborn about solving these problems so it's nice to be able to post up and say 'weve got rid of the bugger!' haha. It's been work because we've had to literally reverse engineer parts of the software, but we got there.
The 75+ZT diesel community has options now, anyway!
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publié par vb @ 11:28
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