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6 Feb 2008, 14:48 (Ref:2122486) | #1 | ||
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ECU that doesnt need a crank signal required!!
We are desperatly looking for an ECU that doesnt require a crankwheel to run the fueling.
Anyone any ideas?? |
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6 Feb 2008, 17:44 (Ref:2122613) | #2 | ||
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How would it know when TDC is, or what revs you are using? You can, I believe, get systems that work of camwheel mounted sensors (half engine speed), or even flywheel sensors. But unless the ECU knows when to open the injectors, and for how long etc surely it won't work.
And as the question is about fuelling I assume you are on injection rather than carbs. |
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6 Feb 2008, 17:49 (Ref:2122617) | #3 | ||
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Seriously though, the ECU needs to know where the engine is in it's cycle - of course even mechanical injection is timed to engine position. Finding the engine postion from a cam sensor, as mentioned above, is the only other alternative that I can think of but I don't know of any system that offers that option. You could try talking to a few ECU manufacturers - they may be able to configure their systems to work in this way for you, but expect to pay. Last edited by phoenix; 6 Feb 2008 at 17:51. |
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6 Feb 2008, 17:57 (Ref:2122624) | #4 | ||
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One of the smaller ECU companies like, say, Emerald are more likely to be able to adapt something to your needs. Somewhere like Omex or MoTeC (for example) is more likely to just sell items off a list, and leave it up to you to adapt to it... But at the same time I still think you'll fail to come up with a solution without the ECU knowing the crank position somehow.
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6 Feb 2008, 18:13 (Ref:2122639) | #5 | |||
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6 Feb 2008, 21:14 (Ref:2122774) | #6 | ||
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as falcemob said an emerald can be triggered via a dizzy, using either a magnetic or hall effect trigger or a luminition eye, you just need to use a laptop to configure it to suit your setup
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6 Feb 2008, 21:32 (Ref:2122791) | #7 | ||
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The only problem with using a cam sensor or a dizzy (if it has one) is that unless it is crank sensed it wont be 100 percent accurate. I wonder why you can't use a sensor on either end of the crank, unless you are trying to hide something !
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Balls of steel (knob of butter) They're Asking For Larkins. ( Proper beer) not you're Eurofizz crap. Hace más calor en España. Me han conocido a hablar un montón cojones! Send any cheques and cash to PO box 1 Lagos Nigeria Africa ! |
6 Feb 2008, 22:14 (Ref:2122836) | #8 | |||
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7 Feb 2008, 06:14 (Ref:2123003) | #9 | |
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Depends on what the factory engine has for a trigger, if any.
If you don't care about sequential injection then pretty much any after market ECU should be able to do the job by interfacing with a cam sensor. For example, Haltech, MoTeC (etc) can read the 360 degree CAS (Cam Angle Sensor) on a Nissan RB engine. The sensor has a slot for each degree of rotation and several offset slots to determine cylinder position/number for sequential injection. |
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7 Feb 2008, 19:16 (Ref:2123444) | #10 | |||
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as i recently did when replacing an old old 1970's management system with an emerald but for various reasons fitting a trigger wheel etc wasnt feasable, it works just fine on a relatively low revving engine, but not ideal for very high rpm use with a dizzy only giving 1 signal per rpm, but trigger wheels commonly giving 36 or 60 per rpm |
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AKA Guru its not speed thats dangerous, just the sudden lack of it! |
7 Feb 2008, 19:39 (Ref:2123459) | #11 | ||
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Fair point I suppose - use the ECU to do the spark advancing. Makes sense if I use my brain - I was only thinking about using it for fuelling as the thread starter required
Maybe the ECU can also 'interpolate' the crank position based on revs, rate of rpm increase and perhaps throttle opening or something, so it's nearly the same as having multiple crank sensing positions? |
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8 Feb 2008, 10:10 (Ref:2123933) | #12 | ||
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With a single cam sensor the input to the ECU would be once in every 720 crank degrees. This would make detection of changes in engine speed much less accurate, so timing of fuel injection - and sparks if used for ignition too - would also be less accurate. The 360 degree sensor on the Nissan engine mentioned above sounds like an excellent solution if not using a crank sensor. |
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8 Feb 2008, 10:46 (Ref:2123955) | #13 | |
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How about a carburettor?
I once adapted a Nissan CAS to a different engine for an aftermarket ECU. While it was effective and it worked there was some custom work involved and the advantages weren't that great. Even then my aftermarket ECU (Haltech) to my knowledge didn't use the full 360 deg (actually really only 180 marks on the disc and it runs at half speed from the camshaft) capability because all it needs to know is when TDC is and when TDC is approaching in order to trigger the correct igniter. This is not an emissions critical setup so you can afford an extra half a crank on the starter (so it can calibrate itself) before it starts. On the Nissan disc are a different set of 4 (or 6 if 6cyl) windows that signify the approaching cylinder for the ECU. There is a bit of variation in the disc types between engine models so be wary. If it was a race car I'd just setup a hall effect or magnetic sensor from the flywheel. It's been done a million times before and is more reliable than the dizzy (which incidentally will need to have the advance springs/weights/etc locked or removed). Any decent ECU should be able to adapt to the sensor on the flywheel. If it can't you shouldn't be using it |
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9 Feb 2008, 12:54 (Ref:2124879) | #14 | ||
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You need Ref and Sync sensors, which is why most Cam triggers have a missing tooth, or additional tooth. The ECU needs to know where TDC is and where it is in the cycle between that. I suspect you could run with just a TDC sensor, but might have fun trying to find hardware that will let you do that. We've commonly used MoTec with mag sensors in the dizzy (locked up of course), no problems in hot 4AGES (Toyota 1600 or sometimes stroked to 1900cc) spinning to 8500rpm.
Not 100% accurate ? If the dizzy ain't accurate, the cams ain't accurate and then you've got bigger problems than worrying about your maps being off by 2/5ths of stuff all. |
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10 Feb 2008, 03:41 (Ref:2125361) | #15 | |
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True.. but often the cam and distributor are driven by a long floppy belt
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10 Feb 2008, 17:02 (Ref:2125828) | #16 | ||
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On my post 7 I said that you can't get 100 pc accuracy unless you use some sort of crank sensor, regardless of whatever trick ECU,s or programme's . Even gear driven cams (although obviously better) have still got that "gnats" of backlash. This may or may not make blow all difference to the fuel timing and ultimate HP output but it still ain't accurate !
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Balls of steel (knob of butter) They're Asking For Larkins. ( Proper beer) not you're Eurofizz crap. Hace más calor en España. Me han conocido a hablar un montón cojones! Send any cheques and cash to PO box 1 Lagos Nigeria Africa ! |
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