megajolt and flapper efi

karlos01 · Post by **karlos01** » Sat Jun 11, 2011 9:42 pm

hi all ive been thinking about a potential problem i might have here.

in this post http://www.v8forum.co.uk/forum/viewtopic.php?t=150 its stated i need to put a lead on the -ve of the coil to trigger the efi. now with MJ i wont have a -ve on the coil.

how the hell do i make the efi fire?

DaveEFI · Post by **DaveEFI** » Sat Jun 11, 2011 11:09 pm

karlos01 wrote:hi all ive been thinking about a potential problem i might have here.

in this post http://www.v8forum.co.uk/forum/viewtopic.php?t=150 its stated i need to put a lead on the -ve of the coil to trigger the efi. now with MJ i wont have a -ve on the coil.

how the hell do i make the efi fire?

Are you using multiple coils? Normal way would be to take a feed from each coil LT negative via a diode, link the outputs of the diodes, then feed that to the ECU via the normal resistor.

But surely this is covered in the MJ manual?

karlos01 · Post by **karlos01** » Sun Jun 12, 2011 6:52 pm

im yet to buy the MJ set up and want to make sure all my bases are covered and have no bad suprises. i want to get it all ready to put in easily.

i have 2 early ford coil packs all ready. im going to be making the looms soon

karlos01 · Post by **karlos01** » Sat Jul 09, 2011 11:43 am

right ive come to wire it all together now, looking for the wire to feed the efi. i dont appear to have it at all.

can this be right?

DaveEFI · Post by **DaveEFI** » Sat Jul 09, 2011 12:40 pm

karlos01 wrote:right ive come to wire it all together now, looking for the wire to feed the efi. i dont appear to have it at all.

can this be right?

Can you post a link to the MegaJolt wiring diagram you're using?
Might it be called 'tach'? This seems to be the US terminology for an ignition feed to the injection.

karlos01 · Post by **karlos01** » Sat Jul 09, 2011 1:29 pm

na i mean i have got that bit sussed, the range rover flapper loom doesnt have the supposed wire. ive got a relay with a couple of wires on it that doesnt appear to go anywhere but no wire that is supposed to set the efi to go

DaveEFI · Post by **DaveEFI** » Sat Jul 09, 2011 2:23 pm

karlos01 wrote:na i mean i have got that bit sussed, the range rover flapper loom doesnt have the supposed wire. ive got a relay with a couple of wires on it that doesnt appear to go anywhere but no wire that is supposed to set the efi to go

Originally, it would be a parallel wire from the coil negative via a resistor. Colour is white/black. Goes to pin1 of the ECU. The resistor value is 6800 ohms.

There are two relays - one for ECU power (main), and one for the pump. Note the main relay is a twin output type rather than the more usual SPDT 5 pin ones. As per the factory, the pump one utilises the same type of relay, but a SPDT type can be used instead.

karlos01 · Post by **karlos01** » Fri Jul 15, 2011 10:10 am

i now have pictures of what i think went to the coil

if im right, im thinking the loose wire off this relay goes to the tach out on the megajolt via the diodes off the coil packs?

if this isnt right what the hell can i do? im close to test starting it but still so far away

DaveEFI · Post by **DaveEFI** » Fri Jul 15, 2011 12:44 pm

Is that a custom made loom? It doesn't look like a factory one. You'd also need to say what the wire colours are if a factory loom - your pics don't show that here.

As I said, the ignition feed (ie tach) to the injection comes from the coil negative on a flappper system via a resistor and goes direct to the ECU. Nowhere near a relay. The red diode pack (steering module) on the flapper system is for pump control.

karlos01 · Post by **karlos01** » Fri Jul 15, 2011 2:24 pm

it is 100% guaranteed factory loomfrom an 89 range rover.

that little lot is sprouting from the loom near the afm area. definately a flapper loom and definately a factory one.

the wire colours are black, black and white, white and coming off the relay, blue and white

the other relays are iin the car as is the diode pack

DaveEFI · Post by **DaveEFI** » Fri Jul 15, 2011 6:33 pm

Here's the flapper wiring diagram by Ramon Alban. Note the tach signal feed from the coil to pin1 on the ECU.

ramon alban · Post by **ramon alban** » Fri Jul 15, 2011 7:00 pm

Hello Karlos,

Actually, what you have in your hand is the Range Rover/Land Rover Flapper System "overrun fuel shut off relay" which works in conjunction with a vacuum switch.

This is a different system to the mechanical vacuum valve fitted to the Rover SD1 Efi system.

Their purpose is to shut off injector operation during high manifold vacuum that occurs when decelerating from high speed with throttle closed.

With ignition on, the relay is energised via the vacuum switch and the white wire with the black wire connected to earth

With low vacuum, and the relay energised, coil negative is connected to the relay contacts via a 6800 ohm resistor and the white/blue wire.

The other closed contact on the relay goes to pin 1 of the ECU via white/black wire.

Thus connected the ECU is able to operate the injectors.

When on overrun, and with high vacuum, the relay is de-energised, the contacts open, the running signal from coil negative is disconnected from pin 1 of the ECU and the injectors cease to operate.

The advantages are improved economy and reduced emissions.

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megajolt and flapper efi

megajolt and flapper efi

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