Wideband Lambda Question
Discussion
Evening gents,
A techie question for those clever people on here. I understand that narrowband lambda will simply tell the ECU either OK, Lean or Rich and wideband will actually tell the ECU the AFR so it knows how rich or lean the engine is running. I also understand that on narrowband the ECU either runs closed loop at idle or partial throttle where it adjusts the fuelling based on what the lambdas are saying but on full throttle it will run open loop where it ignores lambda and refers to the map is it cannot adjust the fuelling quick enough.
In my mind ideal scenario would be run of Lambda all the time so the ECU is essentially self mapping and constantly adjusting the fuelling in real time according to the target lambdas values. Is this how wideband lambda works or does that still have open and closed loop operation?
Please feel free to correct me on any of the above if my understanding is not correct.
A techie question for those clever people on here. I understand that narrowband lambda will simply tell the ECU either OK, Lean or Rich and wideband will actually tell the ECU the AFR so it knows how rich or lean the engine is running. I also understand that on narrowband the ECU either runs closed loop at idle or partial throttle where it adjusts the fuelling based on what the lambdas are saying but on full throttle it will run open loop where it ignores lambda and refers to the map is it cannot adjust the fuelling quick enough.
In my mind ideal scenario would be run of Lambda all the time so the ECU is essentially self mapping and constantly adjusting the fuelling in real time according to the target lambdas values. Is this how wideband lambda works or does that still have open and closed loop operation?
Please feel free to correct me on any of the above if my understanding is not correct.
Hi
You are pretty close to the correct understanding. The narrow band sensors, are "narrow" band meaning that the precission of the measurement is only accurate in a narrow band around 14.7 AFR / lambda 1. This makes them unusable if you want the engine to run very lean of very rich.
The wide band sensors do have a "wide" band of AFR where they are thrustable in their messurement.
For the fuling strattegy (open loop/closed loop) is it prefferrable to run closed loop as much as possible, but due to the inertia of the regulation loop, are there situations where it's nessasary to go in open loop mode. eg. when blipping the throttle do you need a rich mixture (accelleration pump effect) and when you engine brake from wigh revs do you need no fuel at all. So in these situations do you go for an open loop strategy.
I'll post a couple of pics from My ECU later today for further explenation
You are pretty close to the correct understanding. The narrow band sensors, are "narrow" band meaning that the precission of the measurement is only accurate in a narrow band around 14.7 AFR / lambda 1. This makes them unusable if you want the engine to run very lean of very rich.
The wide band sensors do have a "wide" band of AFR where they are thrustable in their messurement.
For the fuling strattegy (open loop/closed loop) is it prefferrable to run closed loop as much as possible, but due to the inertia of the regulation loop, are there situations where it's nessasary to go in open loop mode. eg. when blipping the throttle do you need a rich mixture (accelleration pump effect) and when you engine brake from wigh revs do you need no fuel at all. So in these situations do you go for an open loop strategy.
I'll post a couple of pics from My ECU later today for further explenation
Maybe this thread gives you a little bit more information about Wideband Lambdas:
www.pistonheads.com/gassing/topic.asp?h=0&t=13...
www.pistonheads.com/gassing/topic.asp?h=0&t=13...
That is screen is unreal. I cannot even begin to imagine how you have designed that. Incredible!
Will that work with the newer MBE ECUs specifically the 9A8 and 9A9? The reason behind the wideband question was I am keeping an eye on aftermarket ECUs and I am trying to work out which features I need. I like the look of the new TVR Power MBE ECUs as a retro fit option for my Griff and the fact it is a drive in drive out service. TVR Power are offering the 9A8 and 9A9 MBE ECUs, I believe the 9A8 is narrowband but the 9A9 is wideband and also supports knock sensors. I have been speaking to Power about the possibility of adding an ODBII interface so that any garage can diagnose EFI faults with standard tools. I have a 14CUX handheld tool for my current ECU but I don't like the idea of having to have a laptop with specific software on to diagnose issues with an aftermarket ECU. That screen would most certainly solve that problem.
Will that work with the newer MBE ECUs specifically the 9A8 and 9A9? The reason behind the wideband question was I am keeping an eye on aftermarket ECUs and I am trying to work out which features I need. I like the look of the new TVR Power MBE ECUs as a retro fit option for my Griff and the fact it is a drive in drive out service. TVR Power are offering the 9A8 and 9A9 MBE ECUs, I believe the 9A8 is narrowband but the 9A9 is wideband and also supports knock sensors. I have been speaking to Power about the possibility of adding an ODBII interface so that any garage can diagnose EFI faults with standard tools. I have a 14CUX handheld tool for my current ECU but I don't like the idea of having to have a laptop with specific software on to diagnose issues with an aftermarket ECU. That screen would most certainly solve that problem.
A shot from a dyno session yesterday from a Triumph TR6 with a eaton compressor and a Vems ECU. The wideband sensor is absolutely needed to get the fueling right, and most of all, a helpfull friend when it comes to all the small adjustments of throttle pump, varmup fueling, idle control etc.
Another shot, showing the car running stable at 2000 rpm, with a lean mixture to save fuel, then hitting the pedal, closedloop is turned off as the throttle pump effect is present (it's a little too lean at this stage) and as soon as the circumstances are stable do it swithc closed loop on again (the red bar show's EGO on) And under engine breaking and in idle are EGO off (my choise in the setup)
Another shot from my M, where I run with dual wideband lambda's (red and green line in the bottom window) so each bank of cylinders are adjusted. This do allso give a warning if the 2 banks are not equal in lambda, typically if one cylinder is misfiring.
And ofcause my 0-100kmh run in 3.8 sec :-)
Another shot, showing the car running stable at 2000 rpm, with a lean mixture to save fuel, then hitting the pedal, closedloop is turned off as the throttle pump effect is present (it's a little too lean at this stage) and as soon as the circumstances are stable do it swithc closed loop on again (the red bar show's EGO on) And under engine breaking and in idle are EGO off (my choise in the setup)
Another shot from my M, where I run with dual wideband lambda's (red and green line in the bottom window) so each bank of cylinders are adjusted. This do allso give a warning if the 2 banks are not equal in lambda, typically if one cylinder is misfiring.
And ofcause my 0-100kmh run in 3.8 sec :-)
Don't know if my software will work with the newer MBEs as I don't have the possiblity to test it.
Regarding the choice of Lambda Sensors: Go the Wideband Lambda way, they are much better overall, more reliable.....
Regarding your wish of an universal OBD2-Check possibility: I won't go this way, because the standardized OBD2 Protocol won't let you go into the details. But if you have a fault, these details could be handy. Get the proper USB-Interface for the new MBE and the software from them. This would be the best way to go.
You could buy a used small computer like a Sony Vaio UX or Vaio P and you can diagnose the whole ECU everywhere....
Regarding the choice of Lambda Sensors: Go the Wideband Lambda way, they are much better overall, more reliable.....
Regarding your wish of an universal OBD2-Check possibility: I won't go this way, because the standardized OBD2 Protocol won't let you go into the details. But if you have a fault, these details could be handy. Get the proper USB-Interface for the new MBE and the software from them. This would be the best way to go.
You could buy a used small computer like a Sony Vaio UX or Vaio P and you can diagnose the whole ECU everywhere....
Many thanks for the info gents, you have convinced me dual wideband is the way forward. I like the idea of running dual wideband lamdas to see the exact AFR between the two banks. Thanks for taking the time to post up all those graphs with explanations Mads that really helps and much appreciated
Interestingly enough MBE are re-designing their MBE995 display, apparently replacing it with a screen. I wonder if they have taken any inspiration for your epic screen Oliver.
http://www.sbdev.co.uk/Engine_Management_Systems/E...
Interestingly enough MBE are re-designing their MBE995 display, apparently replacing it with a screen. I wonder if they have taken any inspiration for your epic screen Oliver.
http://www.sbdev.co.uk/Engine_Management_Systems/E...
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