Question about flap openers.

Elder · Post by **Elder** » Sat Apr 21, 2007 1:57 pm

I have a 3.5 EFI A Rangie.
It as the Lucas L flap air meter, and a plenum mounted LPG mixer, but no flap opener. It runs well on gas, but doesn't idle at all.

It has been suggested that as the mixer is mounted after the meter I need a flap opener/exclusion device.

Can anyone point me towards one other than the Chris Perfect/Iwema model? The vap is a Kar-Gas/Longas Airod and apart from fine tuning once I get it idle everything works great.

ChrisJC · Post by **ChrisJC** » Thu Apr 26, 2007 5:59 pm

I have the Chris Perfect one, and found that it also needs a vacuum reservoir to work properly. Otherwise when it changes over it can stall as there's not enough vacuum to make the flap open properly and it chokes the engine to death.

Not that that quite answers your question!

Chris.

badger · Post by **badger** » Thu Apr 26, 2007 8:45 pm

As already stated on the landrover newsgroup - fit the correct mixer!

Elder · Post by **Elder** » Thu Apr 26, 2007 10:39 pm

badger wrote:As already stated on the landrover newsgroup - fit the correct mixer!

I'm not sure that I wouldn't need the opener as well as the mixer though.

As without the opener, isn't it going to be starved of gas and air instead of just air when the flap shuts?

ChrisJC · Post by **ChrisJC** » Fri Apr 27, 2007 6:52 am

I fitted a plenum mixer without a flap opener, and couldn't get it to idle because of the extra vacuum created by the flap being nearly closed. Poke your (or an assistants) finger into the flap to hold it open when it changes over and see if it idles then......

A flap opener sorted mine out nicely. Until LPGi comes into play.....

Chris.

Elder · Post by **Elder** » Fri Apr 27, 2007 7:53 am

Thanks Chris, and yes, direct injection would be nice but I'm sure it would cost more than the vehicle cost me.
And Badger, I do appreciate what you are saying about the mixer before the flap, and if I was sorting bits for a new install, then yes , that is what I would do, but As everything is fitted, in a partially working state, with hoses that don't leak and the correct length, I don't want to mess with what aint broken yet, until I know more about what I'm doing.

badger · Post by **badger** » Fri Apr 27, 2007 8:00 am

Which is why, speaking as an installer of LPG systems for some 8 years now, I keep telling you what mixer to fit for it to work properly!
As it stands, it IS broke and DOES need fixing. With the correct mixer fitted to the inlet face of the airflow meter, there is no need for a flap opener at all, it will then work properly. Remove the existing mixer, reconnect the air inlet pipe to the plenum chamber, re-route the gas feed pipe to the new mixer, set up idle and max flow adjusters, job done.

Elder · Post by **Elder** » Fri Apr 27, 2007 12:18 pm

badger wrote:Which is why, speaking as an installer of LPG systems for some 8 years now, I keep telling you what mixer to fit for it to work properly!
As it stands, it IS broke and DOES need fixing. With the correct mixer fitted to the inlet face of the airflow meter, there is no need for a flap opener at all, it will then work properly. Remove the existing mixer, reconnect the air inlet pipe to the plenum chamber, re-route the gas feed pipe to the new mixer, set up idle and max flow adjusters, job done.

But then I will still need some kind of backfire protection too, which the system doesn't have at all. I know I could leave clamps a little loose, and a well setup system "shouldn't" backfire. But Shouldn'ts do sometimes still happen.

ChrisJC · Post by **ChrisJC** » Sat Apr 28, 2007 9:18 pm

I originally had the mixer between the flap and the air-filter, and a backfire pressure relief device on the engine side of the flap.

It worked great, but the hole in the mixer was so small that I might as well have fitted a lawnmower engine.

So I fitted a much larger mixer on the plenum, got back most of the performance, but got into the troubles described above, fixed by fitting a flap opener and vacuum reservoir.

Badger - if I understand you correctly, one could obtain a mixer to go on the plenum which doesn't need a flap opener?

Chris.

Elder · Post by **Elder** » Sat Apr 28, 2007 10:13 pm

Nope, badger is saying put the mixer infront of the flap.

BTW, how is the chris perfect flap plumbed and wired?

I got a sheet of instructions for plumbing the Y piece onto the opener, but nothing about about how to plumb or wire the electrical switch/solenoid.

It has two terminals and three outlets.

Is the electrical a pass through or is it live and ground?
Which two of the outlets do I connect the hose to? Or is it essentially an active T piece?

Any help would be appreciated.

ChrisJC · Post by **ChrisJC** » Sun Apr 29, 2007 6:54 pm

You can see the wiring I have:

The two connections that are next to each other are the switched two.
The top / left one in the pic goes to the vac reservoir. The one that goes to the right goes to the flap opener.

The wires on the bottom - black is gnd, blue goes to the +12V that gets switched on when the system is on gas.

Chris.

Elder · Post by **Elder** » Sun Apr 29, 2007 7:12 pm

OK, I had the flap and the solenoid plumbed and wired correctly. I used the same live and ground as the vaporiser uses.

But I'm not sure where to get the vacuum feed from.

I switched from petrol to gas with revs, and the filter off and got the GF to watch the flap and opener. the flap moved with revs, but the opener never moved at all.

I tried everything that looked like a small bore vac line, even the dizzy advance line. Nothing made it move.

BTW, on the drivers inner wing, there is what appears to be a vac reservouir with hose coming from the back of the plenum and another disappearing behind the throttle fittings. What is that?

ChrisJC · Post by **ChrisJC** » Mon Apr 30, 2007 7:14 am

I took my vac feed from the back of the plenum (tee'd into the vac feed to the fuel pressure regulator). I passed it via a vac reservoir.

I think the spherical thing located in the spare battery tray on a Rangie is a vac reservoir, but I don't know which connection is which.

I found that a lot of care was required fitting the flap opener to the air flow meter, otherwise the linkage tended to bind / not move freely enough to open the flap.
Might be worth taking it off and seeing if it moves freely.

Chris.

Elder · Post by **Elder** » Mon Apr 30, 2007 9:29 pm

ChrisJC wrote:I took my vac feed from the back of the plenum (tee'd into the vac feed to the fuel pressure regulator). I passed it via a vac reservoir.

I think the spherical thing located in the spare battery tray on a Rangie is a vac reservoir, but I don't know which connection is which.

I found that a lot of care was required fitting the flap opener to the air flow meter, otherwise the linkage tended to bind / not move freely enough to open the flap.
Might be worth taking it off and seeing if it moves freely.

Chris.

OK, I'll check if things are binding. And I'll use the one from the back of the plenum.

I think I might see if I can get my hands on an old Saab 900 vacuum tank. They have a one way valve in and Saab use the vacuum system to operate the heater flaps in the car. Mighty useful things they are.

Elder · Post by **Elder** » Tue May 01, 2007 9:57 pm

Seems to move freely enough.

Can't seem to get any vacuum from any of the plenum vacuum lines either.
Very odd.

Now petrol idle is going to cock, and no matter what I do to adjust it, it goes back out again within a few minutes.

And I can't find the idle air bypass wiring to disconnect it, which is probably where I'm going wrong. I get hunting, then stumbling then low idle, then hunting when trying to manoeuvre/steer at just above idle speeds, then eventually dying.

But my luck isn't very good at the moment anyway. I can't even find a decent supply of roughly the right sized vacuum hose. Everything locally is bright coloured and seems to be about £3 a meter and only sold in tiny lengths, so I can't even buy a small roll and change everything.

That is, if I could see where about behind the plenum all the hoses go to.

They all disappear behind the drivers side and the fairly tight coolant hoses for the LPG sit over the top of them.