hi im fitting my v3 mj map,
can i use the vac off of the carbs,i have some zx9r carbs,
or i have a outlet on the manifold.
also the 4 prog wires im not gona use so do i just leave them disconected???
please help asap as i am fitting this today,
thanks you very much
jamie
help please asap vac hose
Moderators: JeffC, rdoherty, stieg, brentp
Hi Jamie,
You want a vacuum reference port that provides a steady vacuum reference across all of your cylinders. This port is always after your throttle bodies.
So it looks like you're running bike carbs. Does your manifold have a balance tube across the runners?
if not, you may need a vacuum reservoir similar to what's described here:
http://www.autosportlabs.net/MJLJ_V4_ve ... _operation
to ensure you have a smooth vacuum reading across all cylinders.
A good way to monitor you vacuum readings is to use a manual vacuum gauge.
Feel free to snap some pictures of your setup and attach them to your reply in this thread.
Regards,
You want a vacuum reference port that provides a steady vacuum reference across all of your cylinders. This port is always after your throttle bodies.
So it looks like you're running bike carbs. Does your manifold have a balance tube across the runners?
if not, you may need a vacuum reservoir similar to what's described here:
http://www.autosportlabs.net/MJLJ_V4_ve ... _operation
to ensure you have a smooth vacuum reading across all cylinders.
A good way to monitor you vacuum readings is to use a manual vacuum gauge.
Feel free to snap some pictures of your setup and attach them to your reply in this thread.
Regards,
Personally I'm not a fan of the balance pipe arrangement. Whilst it does smooth the individual pulses it does so at the cost of dynamic range - knocking the peaks and troughs off means that you can end up with misleading results.
The example of this is with the engine off you see 100kpa so think that 100kpa is full throttle and indeed it may be at some points of the rev range, but at others when the pulse tuning is most effective full throttle may only be 90kpa and your full-throttle setting needs to be in a different cell in the map. Normally a decrease in pressure at higher revs indicates that your throttles are too small but that isn't necessarily the case here as your WOT value may go from 100kpa down to 90kpa, back up to 100kpa, down again to 95 kpa as the second order effects kick in, before climbing back up again. All of which has scope to confuse! That's not to say a single takeoff is that much better but what you can find is that you'll rather than dipping the pulse tuning serves to increase the level slightly above 100kpa, which is actually a much more representative reflection of what is going on.
My preference is to use a single take off and in that, if and only if it proves necessary, to use a fuel filter/mig tip to smooth the signal.
The example of this is with the engine off you see 100kpa so think that 100kpa is full throttle and indeed it may be at some points of the rev range, but at others when the pulse tuning is most effective full throttle may only be 90kpa and your full-throttle setting needs to be in a different cell in the map. Normally a decrease in pressure at higher revs indicates that your throttles are too small but that isn't necessarily the case here as your WOT value may go from 100kpa down to 90kpa, back up to 100kpa, down again to 95 kpa as the second order effects kick in, before climbing back up again. All of which has scope to confuse! That's not to say a single takeoff is that much better but what you can find is that you'll rather than dipping the pulse tuning serves to increase the level slightly above 100kpa, which is actually a much more representative reflection of what is going on.
My preference is to use a single take off and in that, if and only if it proves necessary, to use a fuel filter/mig tip to smooth the signal.
On the subject, be sure to review the sticky we have here- some great analysis on the effects of different plenum / reservoir sizes:
http://www.autosportlabs.org/viewtopic. ... sc&start=0
http://www.autosportlabs.org/viewtopic. ... sc&start=0