Vacuum over boost or vice versa?

[mrzigazaga]

Hi Peeps..A good point was made earlier as to the connection of the vacuum from the throttle body which used to control the advance/retard by being connected to the vacuum diaphragm on the dizzy..Now that i have the amethyst hooked up a feed from the plenum has been taken and the two have now been married to a leak valve via a "T" connector..Not quite a one way valve..And then fed to the MAP sensor on the ignition unit..I know that boost and vacuum are totally different energies and wondered what effect this is having..I would of thought that the map sensor would only need a feed from the plenum to measure boost??..On the amethyst diagram it shows a pic of the unit and indicates that the MAP sensor should by connected to the inlet manifold..Maybe this is why it wont idle under 1100rpm..Cheers...Ziga

[adam quantrill]

Yes get rid of the tee and the connection to the throttle and go directly to the plenum with no valve.

[mrzigazaga]

Cheers Adam..As i thought...Ziga

[ralph350i]

Another one ticked off the list mate and hopefully your tickover will be sorted, cheers

[mrzigazaga]

ralph350i said:

Another one ticked off the list mate and hopefully your tickover will be sorted, cheers

MMmm...Could be the reason mate..Boost pressure is obviously more powerful than the vacuum so it could be closing the sensor plate when returning to idle and probably why the garage set the rpm to 1100...I will give it a try tomorrow...Cheers...Ziga