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Thread: Individual cylinder trims getting me down

  1. #1
    Constant Bitrate AutoWiz's Avatar
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    Individual cylinder trims getting me down

    I think I need help in finding a new Engine Management System. I currently have an all aem(series2) setup. the last component I purchased for my 2.0L Honda build is aem's 4 channel wideband controller. my specific goals for this component is to enable individual cylinder fuel trims in feedback, or closed loop operation. in aem tuner the individual cylinder fuel trims are a 2-d map that lets me adjust injector duty cycle vs. rpm but in a fixed manner. this will allow me to compensate for the allowable differences in cylinder compression or injector flowrates from one cylinder to the next, but will not help the other 3 cylinders from leaning out should 1 injector hang open or 1 spark plug not fire. upon consultation with aem, i am told they do not have any controller that supports 4 channels of o2 feedback. and do not have any intensions of creating or supporting this feature in the future that they know of. so, I need to steer myself towards a new ems. one that will support 4 channels of o2 feedback. not just monitoring. I am looking to tie each injector to a different o2 sensor and have each cylinder trim itself. anybody here have any suggestions on which brand or specific ems will or might support this feature???

  2. #2
    Raw Wave
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    IOW O2 sensors are not fast enough? (Just as I thought.)

    So are they fast enough to react to a single cycle (2 crank rotations)? Not that I think they can be mounted in each header, and I suspect with a newish engine (4 valves per cyl etc) you would not want long headers...(??)

    The only method I know for what you want is ionic. O2 sensors just don't cut it - tho I may be out of date re O2 sensor technology (not that afaik the basics have changed - ergo, still useless).

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    Constant Bitrate AutoWiz's Avatar
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    aem uses bosch 4.2 uego o2 sensors. they are among the best on the market. and they never need a free air calibration. the 4 channel wideband controller is designed and built for individual cylinder fuel trims, so It doesn't have to operate or switch at a higher speed than any other o2 application would. it will trim at the same speed as always, just localized to 1 cylinder. it comes with tall and finned o2 bungs to tig weld into exhaust header primaries. it's just that usually this setup is used for very high horsepower applications and at the track only. and usually track cars don't even use o2 feedback.

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    Raw Wave
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    So are you saying they have an output reaction time of (say) 10mS or less?

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    Constant Bitrate AutoWiz's Avatar
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    what I am saying is moving an 02 sensor from the collector to a primary and having it read 1 cylinder does not require the o2 sensor to have a faster reaction time. i'm not looking to trim individual combustion events, just individual cylinder fuel trims. in feedback. so if 1 fuel injector fails, the ecu doesn't dangerously lean out the other 3 cylinders trying to compensate.

  6. #6
    Raw Wave
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    Yeah, but what I was saying was that afaik, O2 sensors were not fast enough. You said they were but later that you could not trim properly which sounded to me like a timing/delay issue.

    So what is the reaction time of the 4.2 uego 02 sensors?


    BTW - when I say DIY EFI, I mean DIY programming etc - not the mere DIY tuning. Hence fully configurable as you want. If that can use existing hardware, fine, but my DIY EFI/EMS was a full build.

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    Constant Bitrate AutoWiz's Avatar
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    megasquirt is so much less than aem's series 2 ems'. I did my homework. yes you can solder chips to a board, but in the end, the aem solution has better features, a more intuitive software suite, is more reliable, and 3 times as much money. proof of this is everybody I have told I want to switch to a different ems asks me the same question. "how much do you want for your aem ems?" I have one friend who wants to trade me for his hondata s300, one friend wants to trade me his 3rd gen megasquirt. I have seen homemade or home assembled megasquirt systems, and imho they are like a radio shack build your own fm radio vs. a fully equipped sony home theater system. the entire ems-4 with connector and completely sealed (waterproof, shockproof) enclosure fits in the palm of my hand. the electronics inside are too small to come in a megasquirt kit. it is all surface mount stuff. not the silicone board with a million holes you get from megasquirt. to build all the features the ems-4 has into a megasquirt, it would be huge. the built in 8mb datalogger, the usb 2.0 connection, the canbus, sequential injector and coil drivers, 8 g.p.i.o.'s with 4 of them supporting pwm. and though I am not positive on this, I am relatively sure that megasquirt will not drive an engine to 25,600rpm. I will never spool my engine to those speeds but it is so comforting to know that even when I am screaming my motor to 9,000rpm, the ecu is not on the verge and beginning to skew injector or coil triggering. anybody that knows of aem and has something else is always and only because of money. nobody says "because aem can't do this or that" or "because aem is unreliable" or any other complaints other than because the controllers are so expensive. and well as always in this life, you get what you pay for. and while I am currently unable to find the specific reaction time of the bosch wideband 4.2 or 4.9 sensor, some controllers sample the o2 reading every 2ms.

    AEM has plug n play ems systems that come with or you can download tune files for and from there it is a matter of tuning. the ems-4 is a universal standalone engine controller. it can be used on a single cylinder 2 stroke, it can be used on a v-twin, or a 3-cyl. geo, or a 4 cylinder, or even 6 or 8 cylinders with batch firing and waste spark. setting up this controller falls more under the category of programming than it does tuning. seriously. you have to tell it how many teeth are on the crank wheel and cam wheel, wether you want it to trigger off of rising or falling edge, wether each wheel is a missing tooth design, and what type of sensors they are(optical/hall or magnetic). then once that is set right, you have to tell it what injectors and coils you wanna use, and at how many teeth on the crank wheel you want each coil and injector to fire. before you can even start setting up a fuel or ignition map, you first have to configure all the breakpoints. so you really create your own maps. and the breakpoints don't have to be linear, so you can have more cells in the idle area if you wanna try to get the smoothest idle possible out of it. I strongly encourage you to download the latest version of aemtuner and just look around at/in it. the software is free. it is as diy as you'd ever wanna get.

    my problem isn't that my o2 sensor isn't trimming. it works fine. it is that I know that if an ignition coil arcs to ground rather than through the spark plug and that 1 cylinder doesn't fire, the 1 wideband I have downstream of the collector is gonna see rich and lean then other 3 cylinders out. this same thing will happen if an injector fails. or if 1 injector stops firing and is getting no fuel whatsoever, the ems will never see this or at best it will riched the other 3 cylinders a touch. I want feedback, or closed loop, or automatic trimming on each cylinder individually instead of looking at the exhaust of all 4 cylinders together. I want more precision in my engine's fueling than an average afr of all cylinders. I want to treat each cylinder like it is it's own engine.
    Last edited by AutoWiz; 01-20-2014 at 06:45 PM.

  8. #8
    Raw Wave
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    Are you replying to me? If so I don't understand why you are repeating the obvious.
    And maps? Hey man, I'm into self tuning, Maps are things those primitive Haltechs have (all 32 of them LOL!).

    So, what is the response time of the Bosch 4.2?

  9. #9
    Constant Bitrate AutoWiz's Avatar
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    that is going to be determined by the guage/controller for the wideband. some controllers and I believe my ems-4 look at it every 2ms. as far as how fast the actual element can respond in relation to a given combustion event would greatly depend on cylinder volume vs. exhaust diameter and length up to the sensor and maybe exhaust backpressure should also be a part of that calculation to be accurate. yet another reason to move the o2 sensor to just a few inches off the head.

  10. #10
    Raw Wave
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    No. The "sense" time of the 4.2 - ie, how long between a "sample" until its equalisation or equilibrium chamber (or whatever they call it) has the appropriate reading ready. Since that depends of how far off stoich it is, let's assume it's at 14.5 or 14.2 (or whatever the 4.2 quotes) instead of 14.7, and let's not worry about how the sample is triggered (ie, how ever many mSecs after ignition).
    I know EMSs can sample however often, but I want to know the 'reaction' time of a wideband like the 4.2 (which of course is slower than narrowbands assuming the same technology).

    If it were 2ms and your ems-4 looks at it at that rate, I fail to see why you cannot trim appropriately. You should have all the info required. (Granted, IMO it's the same as a typical "self learning" process, and some consider that "impossible"...)

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