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Ben P
Level 5 User
Joined: 04 May 2004
Posts: 107
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Tue Nov 16, 2004 3:29 am |
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Just read the guides on ignition and injection, which are great as I am sure you know.
Just one thing I am not 100% on.
If the crank angle sensor picks up a signal from a single sensor in the bell housing, which is TDC, how does it know which cylinder this is for?
I know this is probably a really stupid question, with a really obvious answer, but it's the only bit I don't quite 'get'
Oh yeah and also, with engines running a twin carb setup, what's the difference and advantages between a 2D and 3D ignition system?
Cheers for any help. |
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Ben P
Level 5 User
Joined: 04 May 2004
Posts: 107
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Tue Nov 16, 2004 6:50 am |
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Ok I have read a bit more and think I understand 2D vs 3D systems.
2D only takes into account speed, not load right?
Anyway still would like someone to explain the CAS question.
(Maybe I have posted in the wrong area and this will never get read) |
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JB
Mr Quoter-vator
Joined: 16 Feb 2004
Posts: 7405
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Tue Nov 16, 2004 8:34 am |
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2 sensers on the flywheel for the two TDC positions....then when it fires its up to the dizzy cap to fire the right cylinder....which ever the rotor is pointing to. |
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Ben P
Level 5 User
Joined: 04 May 2004
Posts: 107
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Tue Nov 16, 2004 9:39 am |
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Gotcha! So on cars like pugs which have coil packs instead of a dizzy cap, do they just fire 2 at once? |
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JB
Mr Quoter-vator
Joined: 16 Feb 2004
Posts: 7405
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Tue Nov 16, 2004 10:16 am |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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Wed Nov 17, 2004 3:37 am |
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non coil pack engine run a 2 pickup flywheel. This makes the coil fire when either 1 and 4 are at TDC or when 2 and 3 are at TDC.
The dizzy cap routes the spark to whichever cyl needs it. L:ike JB said.
Coil pack engines run wasted spark, this means coil pack(s) in which 1+4 and 2+3 share a coil. The fly only has 1 tooth instead of 2, at cyl 1+4 TDC, it fires on both these cyls, 1 when it should and 4 on its exhaust stroke (thus wasted spark). 2+3 are fired when they should be by the ECU estimating things. |
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JB
Mr Quoter-vator
Joined: 16 Feb 2004
Posts: 7405
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Wed Nov 17, 2004 4:19 am |
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that sounds worse than a dizzy set up....whats the benefits? |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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Wed Nov 17, 2004 5:11 am |
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better spark, less chance of missfire, better emmisions and power due to less chance of missfire plus it can fire the plug in very rich and weak conditions. |
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JB
Mr Quoter-vator
Joined: 16 Feb 2004
Posts: 7405
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Wed Nov 17, 2004 1:30 pm |
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i see...fair enough. must be worth it obviously for them to do it. |
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stan
Gay Rights Activist
Joined: 07 Apr 2004
Posts: 1268
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Wed Jan 12, 2005 2:38 pm |
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and less resistence due to no leads/rotor arm etc=more "powerful" spark. also a so-called cleaning effect when spark occurs on non firing stroke....maybe/maybe not! |
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JB
Mr Quoter-vator
Joined: 16 Feb 2004
Posts: 7405
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Thu Jan 13, 2005 5:39 am |
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so wud a car with this method (and assuming this "cleaning"effect) not require egr? |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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Thu Jan 13, 2005 5:46 am |
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no doesn't work like that. The cleaning effect like Stan hinted at is not actually proven conclusively. |
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stan
Gay Rights Activist
Joined: 07 Apr 2004
Posts: 1268
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Thu Jan 13, 2005 6:33 am |
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EGR is just for emmisions. reduces oxides of nitrogen by reducin peak cylinder temp due to the dilution effect it has on combustion |
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JB
Mr Quoter-vator
Joined: 16 Feb 2004
Posts: 7405
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| Posted:
Thu Jan 13, 2005 6:42 am |
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