Fix My Vacuum

[turbo.vixen]

Ok I need to get to the bottom of this, my car only sometimes goes into vacuum when I let off the throttle, so something is stopping it.

The mechanic hooked up some sort of yellow computer to my car and at idle it was reading 4psi when it should be in the minus.

When I take my foot off the throttle and coast, the revs drop to around 2000rpm, stays there and wont slow down anymore due to it staying at 4psi.

If I come up to lights and knock it back to 2nd and am on the brakes it will cackle and splutter, if I put the clutch in it will stall, but if I give the throttle a little tap it smooths out and is fine.

It also has a inconsistent popping/rough idle that gets that bad that it makes the car rock like a boat, but goes away when the aircon fan kicks in, but pops again when it turns off

Its really sh*tting me to tears when I pull up at lights and my car is popping like a pringles packet, so please, if you have any ideas ill try anything

[Mike XR6T]

sounds like an air leak mate, a hose off or a gasket sucking air in when it shouldnt

[turbo.vixen]

mmm someone once said that it might be the intake manifold gasket, theres no leaks in the pipes, checked it all

[ms700]

So the intake manifold is registering 4psi at idle?

Id be hooking up a independant vacuum meter to the intake manifold somewhere, and see what the go is.

Sounds like something simple, like a split hose.

or the johnson rod may have come out of alignment.

[turbo.vixen]

ok so its not the intake manifold gasket.......

Edited 10/09/09 08:49 AM by turbo.vixen

[Rootster]

well jamie after looking at the topic fix my vacumm...I was wondering how you broke it but anyway....It could be the live wire on the accelerator pedal....or the throtle postioning switch...My old ba v8 would carry on like that...took it back to ford they replaced the switch and all fixed...also had a small vaccum leak behind the dash....

Edited 10/09/09 09:56 AM by Rootster

[ETM]

do your brakes work ok?

[turbo.vixen]

thanks nick ill get it looked at

umm etm, not sure if that was a trick question but yes they are fine

[ms700]

nah, wouldnt have been a trick question, your brake booster relies on vacuum from the intake manifold.