timex
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| posted on 30/9/07 at 07:34 PM |
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Megajolt Rev limiter?
Ok, i know that the standard Megajolt rev limiter puts the timing to, 0 Degrees BTDC when it kicks in. We have checked that it is working by seting it
to about 2000RPM and reving it up to that and as soon as it gets to 2000RPM the advance drops to 0 degrees. Even tho the timing goes to 0 degrees you
can still rev it way above that with out no strugle? Is this normal? We cant try it when driving the car yet has it aint legal!
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David Jenkins
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| posted on 30/9/07 at 07:46 PM |
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Doesn't sound right, although I've never set mine so low. When I reach the limit I've set (6300) the engine runs very flat and
won't go much faster.
As a matter of interest, have you tried unplugging the MJ box to check the static timing? When it runs in 'get you home mode' you get 10
degrees fixed advance - worth trying to ensure that all is OK.
David
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MkIndy7
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| posted on 30/9/07 at 07:56 PM |
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Is that revving it up in the drive/garage or driving it?
I should imagine when the engine is loaded up the retardation in timing would make the engine quite hesitiant
*Doh... just read the post again, U can't try it whilst driving!
The engine will probably idle and rev up ok with massively varying degrees of timing, its when the engine is loaded up that it makes a massive
difference.
[Edited on 30/9/07 by MkIndy7]
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timex
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| posted on 30/9/07 at 08:01 PM |
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Well we only just set it at 2000RPM just to se if it was working realy. Didnt think the neighbours would be too impresed if we was reving it up to
6000RPM. Are engine tisks over at around 1000RPM and when we set it to 500 it did slow tick over down. It is seting advance to 0 degrees. Do you think
it would be more efective if the engine was under load, I.E being driven?
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timex
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| posted on 30/9/07 at 08:26 PM |
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Just had a look at the Megajolt diagram and pin 13 is rev limiter. Does this have to connected to anything?
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CaptainJosh
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| posted on 30/9/07 at 08:26 PM |
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I used to run a revlimiter on my mini, if it wasn't underload the engine would still rev past limiter, just slower than usual ( with back
firing, because it was a pulsed ignition cut )- but when you launch off holding the 4000rpm cut on the steering wheel, it wouldn't go any
further and it would never go past the main 7000rpm limit.
I did like that little button, sitting on the line grass tracking- rev to 6500rpm foot to the floor, then press the limiter quickly with a little less
throttle, the revs would drop then let go and... BANG! backfire.
The crowd loved it.
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lotustwincam
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| posted on 30/9/07 at 08:29 PM |
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Well, having just rebuilt my crossflow 200 miles ago, and fitted MegaJolt, I haven't yet tried the rev limiter in earnest.
However, for testing purposes, I have set the limiter to 4,000 RPM. When the engine hits that speed under light load, the change in engine note is so
severe that I wouldn't even dare try pushing on any further.
Has anyone else noticed this too. The 290 degree cam probably may have something to do with it.
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David Jenkins
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| posted on 30/9/07 at 08:29 PM |
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quote:
Originally posted by timex
Just had a look at the Megajolt diagram and pin 13 is rev limiter. Does this have to connected to anything?
No - that's for an add-on 'hard cut' rev limit device that is currently in the pipe-line.
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Danozeman
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| posted on 30/9/07 at 08:31 PM |
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My rev limiter pin is not connected to anything, I did the same test as you. When set at 2000 it revs to about 2500 when standing still and under
load dead on 2000 its dead and wont go anymore.
Dan
Built the purple peril!! Let the modifications begin!!
http://www.eastangliankitcars.co.uk
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lotustwincam
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| posted on 30/9/07 at 08:40 PM |
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Timex,
Have you put a timing light on the engine to prove that the ignition is actually going to 0 degrees?
The MegaJolt display shows you what the output of the MegaJolt is telling the EDIS to do. It is possible that there is a break in the SAW line
between MegaJolt and Edis.
So the Megajolt could be telling the EDIS to go to TDC, whilst all the time the EDIS is in 10 degree limp home mode.
Drew
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pajsh
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| posted on 30/9/07 at 09:04 PM |
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When I first started playing with altering the maps I went out and it was running like a dog. Banging coughing etc so I pulled over. With the Laptop
on the passenger seat I could see the advance go to 0 when I revved it but couldn't figure out why.
Then I discovered the rev limiter in the map was set to 2000ish explaining why it would not run right.
I changed it and flashed it to the Megajolt but it seemed to keep reverting back to 2000 everytime I unplugged the laptop.
I sorted it in the end.
I used to be apathetic but now I just don't care.
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MikeRJ
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| posted on 1/10/07 at 07:44 AM |
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Retarding to 0 degrees at 2000RPM under no engine load is going to have a much smaller effect than doing it at 6500RPM with your foot to the floor.
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