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| air fuel ratio monitoring https://www.slantsix.org/forum/viewtopic.php?t=23966 |
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| Author: | Pierre [ Tue Jul 10, 2007 10:05 am ] |
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Sam, I think thats a bit exaggerated. I can show you some of my logs if you want that show you "steady" afr in closed loop. There are several things that affect afr that are out of your control closed loop takes care of. Engine wear, weather, etc. Your not going to get the best mpg you can without closed loop no matter how good your tune is. A small amount of bounce is ok. Variations in exhaust pulses, sensor sensitivity, controller/ecu reporting speeds, you can't control everything. A 100%, rock steady, never budges a bit reading indicates theres some averaging going on somewhere, but thats expected otherwise the display would be changing so fast you can't make sense of it. ECU's themself aren't realtime either. They can change pulse width several times a second so they appear to be, but if you want to get technical about it anything digital isn't real time. |
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| Author: | Matt Cramer [ Tue Jul 10, 2007 4:28 pm ] |
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They both have their place, but closed loop control is best used as minor corrections to a well dialed in fuel table, not as the primary means of controlling the fuel delivery. Although each have their place, I would assign the open loop tuning considerably more importance. |
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| Author: | Sam Powell [ Tue Jul 10, 2007 9:05 pm ] |
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OK, maybe you are right, it is a bit of an exageration, but it looks pretty good. At this point, with the Accel, I have not figured out how to chose an Af ratio other than 14.7:1 in closed loop with a narrow band sensor. I have the broad band installed, but only for the gauge, not for closed loop with the ECU. If I had their wide band kit, which is quite expensive, I could request a specific AF ratio, and it would meet it. That would be great, and maybe some day I will go that route. But with the narrow band sensor, it seems as if 14.7 is it. With Mega Squirt you can fool the narrow band by changing the cross over voltage, and thus force the AF ratio higher if you want. I have not yet found a similar trick for the Accel. I am trying to tune my crusie AF ratio to 16:1, so chose to run in open loop. It appears to hold that pretty steady on the wide band gauge, as I am cruising down the road, as long as I am in the same cell of the map. Of course transients change everything, and do upset the applecart, so to speak. Once the TPS sits still for a second, it settles down again. But I still c ontend that open loop is not that bad if you are willing to tinker with the tuning. And, at least with ACcel, it offers more flexibility if you dont; have their wide band kit. Sam |
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| Author: | Pierre [ Tue Jul 10, 2007 10:10 pm ] |
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Sam if you had good luck with narrowband go for it, I didn't mean to imply it was bad. Clever way of not having to spend more money for the legit kit for your ecu. Running closed loop with an out of whack table will lead to large swings but with megasquirts Autotune it makes quick work of flattening it out, as long as its not so rich to begin with that its misfiring. Fyi - no computer can dictate "I want this afr at that point" using narrowband unles its 14.7. The crossover point setting in megasquirt is to accomodate for the sensor, not for your desired AFR. A narrow band will tell you lean, stoich, and rich, no more no less. Not how lean, or how rich. In the megamanual at this page it basically says if using a narrowband, tune the area to 14.7 then gives the formula for how to adjust the VE table artifically to get the desired afr. While this does force the engine to run at desired afr, it also defeats the feedback mechanisms of the o2 sensor. Incidentally, how much does Accel want for their wideband addon? |
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| Author: | emsvitil [ Tue Jul 10, 2007 11:40 pm ] |
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I think the innovate box can output a signal that mimics a narrowband O2 sensor, and that output can be at any AF ratio........... |
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| Author: | Sam Powell [ Wed Jul 11, 2007 4:52 am ] |
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Pierre, the Accel wide band kit was around $1000 when I purchased the ECU. The irony is that now I have spent nearly that between the original Lamda Boy, and the Inovate I just purchased. But, I bought the Lamda Boy back when I was using MS. Ems, are you saying you think I can take the output from the Inovate processor box and feed it to the Accel ECU? If that is the case, I can specify a specific AF ratio for each cell in the VE table, and perform a function similar to auto tune in MS. I wonder how I would find out if this is possible, and how to do that wiring if it is? Most likely the tech support for Inovate would be where to start. I think there is an output pigtail from the gauge itself which might mean the gauge ends up being in series with whatever other hardware this is intended to feed to. I suspect the gauge output might be for their datalogging system. You can tell I have not opened up their soft ware and studied it yet. There still is not time for that. Maybe next week. WE have a big sale at work this weekend, and in addition I am participating in a model railroad convention this week as well. Sam |
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| Author: | Pierre [ Wed Jul 11, 2007 10:11 am ] |
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Sam, as long as the output mimics a narrowband (or can be programmed to mimic it) yes you can do that. I know the LC-1 kit can, but your particular kit, I'm not sure. |
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| Author: | emsvitil [ Wed Jul 11, 2007 2:40 pm ] |
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Start at page 13.... http://www.innovatemotorsports.com/supp ... Manual.pdf this is for LM1, hopefully yours has same function. |
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| Author: | Sam Powell [ Wed Jul 11, 2007 4:26 pm ] |
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Thanks Ems, I glanced at the manual in the link, and then went out and saw that my kit has the LC-1 and the xd-16. I really wish they would use words instead of acrnyms to name products. There are too many unassociated letters out there in the world now. I am never sure if I got the letters right, and they are so easily confused when only a single letter changes in the acronym. I feel pretty certain that people at Inovate know what the letters stand for, and that they make perfect sense, but they don't mean anything to me, at least at first. Sorry for the rant. I have the CD that came with my kit, and will soon get to reading that text. I don't know how different they are. Thanks again for taking the time to look that up for me. Sam. |
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| Author: | Matt Cramer [ Wed Jul 11, 2007 5:55 pm ] |
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Sam, Here's the LC-1's own manual. The software you use is identical to the LM-1's, and even is called an LM programmer, which can be a bit confusing. Many of the Innovate letters do stand for something, or at least appear to based on Innovate's literature. While they never outright say that the letters stand for anything, they often have a generic description of the product that matches up to the initials. Here are the ones that I'm fairly certain of: LM - lambda meter LC - lambda cable DL - data logger SSI - simple sensor interface TC - thermocouple MTS - modular tuning system There are a few that they haven't explained. Here is some speculation on my part about what other product names could mean. LMA - extension of the LM XD - extendable display DB - digital basic G - gauge I think they called the LC-1 a "cable" because it's a small device designed more to pass the output of a wideband to other devices rather than something that functions on its own. The LM, on the other hand, is a meter like a voltmeter, a big handheld thing. Taken on their own, the letters can easily turn into alphabet soup. I probably wouldn't have a feel for the letters myself unless I had to discuss the whole lineup with customers at various times. |
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| Author: | Sam Powell [ Wed Jul 11, 2007 9:03 pm ] |
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Thanks matt. So you think I can get this Inovate setup to supply a wide band feed to the Accel? There is a selection in the Accel configuration set up for either a wide band or a narrow band sensor. That would be awsome, and would mean I had spent a total of so far of less than the cost of the Accel wideband package, even with the extra expense of buying the lambda Boy first. I have a feeling you are going to be a great resource for me in the next 2 or 3 months. As I have said, I must get my new dash together before all this can happen, and that is an amazingly complex project. All the wiring, and cutting of the original dash stamping, and the detailing, and finishing of the dash panel itself, which will get a coat of laquer to protect it before it gests installed. I didn't realize when I bought the Rocky Mountain Dashes unit how much work would be involved. I have questions about basic wiring,which I am going to throw out there next week, headlights, and wipers kind of stuff.. Sam |
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| Author: | Matt Cramer [ Thu Jul 12, 2007 4:57 am ] |
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Do you know what sort of input the Accel box is looking for on a wideband? While Accel may have tried to deliberately make things difficult, I'm guessing it is some sort of straight voltage input. |
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