Megajolt Help

[Snapperpaul]

I have a second complete Megajolt setup which i am wiring from scratch to try and eliminate some random missfires and ignition dropouts that have been causing me some concern.

One of the symptoms has been the occational blowing of the Megajoly fuse (7.5 amp) I replaced this with a 10 amp which worked for a while then blew a couple again, usually on start up.

 

Does the EDIS need a seperate fuse if so how many amps?

does the wasted spark coil pack 12v feed need a fuse, again if so how big.

In the attached diagram where should the fuses be placed?

Ignore the TPS wiring as i am running MAP.

[Guest mtechautomotive]

I have a second complete Megajolt setup which i am wiring from scratch to try and eliminate some random missfires and ignition dropouts that have been causing me some concern.

One of the symptoms has been the occational blowing of the Megajoly fuse (7.5 amp) I replaced this with a 10 amp which worked for a while then blew a couple again, usually on start up.

 

Does the EDIS need a seperate fuse if so how many amps?

does the wasted spark coil pack 12v feed need a fuse, again if so how big.

In the attached diagram where should the fuses be placed?

Ignore the TPS wiring as i am running MAP.

 

Paul,

 

On a standard ford EEC-IV loom, there is no fuse for the EDIS or coil pack (other than the 'EFI' fuse (15A I believe) for running the entire engine management.

 

Make sure you are using sheilded wire for both the VR (crank) pickup AND the pip/saw comms wires that run to the EDIS module as this will cause misfires. When these missfire events occur, what happens to the readouts, do they drop to zero etc on the RPM?

 

The EDIS system is pretty bulletproof, even if pip/.saw comms go dead it will revert to 10* BTDC advance, leading me to believe that the problem is on the VR wiring to the crank. Make sure you earth the sheilds to the block and NOT too close to the MJ earth as this can cause it.

 

Also, some brands of HT leads (notably the silicone blue hyper type leads are non resistive and can cause issues with EDIS, if in doubt use standard Ford OE HT leads where you can.

 

Matt

[Snapperpaul]

Matt, thanks for the info so far..

I have shielded cable on the new loom but not on the old, with the old wiring that is currently on the car i get a complete drop out of spark with the rev counter, which is driven from the Megajolt, dropping to zero at the same time.

I will earth the Vr shielding to the block, do i need to remove the earth from this shielding that is earthed at the Megajolt end, i.e just earth the shielding at the block/VR sensor end.

Thanks for the info, I feel that i am getting somewhere.

Ta

[Guest mtechautomotive]

Matt, thanks for the info so far..

I have shielded cable on the new loom but not on the old, with the old wiring that is currently on the car i get a complete drop out of spark with the rev counter, which is driven from the Megajolt, dropping to zero at the same time.

I will earth the Vr shielding to the block, do i need to remove the earth from this shielding that is earthed at the Megajolt end, i.e just earth the shielding at the block/VR sensor end.

Thanks for the info, I feel that i am getting somewhere.

Ta

 

Paul,

 

If the rev counter is dropping to zero then you have a problem between the EDIS module and the MJ. The MJ is either losing signal (and hence RPM) or, its a power issue. You have to make sure the supply to the coils and the MJ is man enough for the job, toooo many problems are caused by too thin a cable carrying current. When you are at high RPMs, the coils are *almost* always on, and if the wire has a higb resistance (and if you have coil power and MJ power sharing a line) then it may cut the MJ out.

 

The new loom should solve it all though, just make sure everything is as good as it can be. No scotch locks, chocolate blocks or bullet connectors if you can help it, just good old solder and heatshrink

 

Let me know how you get on!

 

Cheers,

Matt

[Snapperpaul]

Matt with your info taken into account, i will run a complete new power feed direct from the battery in larger cable and then distribute it to the coil pack, EDIS and Megajolt (7.5 amp fuse) using switches instead of the weedy supply from the ignition switch. All this will be on a seperate board bolted under the scuttle until i get a switch panel fitted in the dash.

All the wiring has been soldered and heatshrink added, the only plug is the Molex for the Megajolt.

I was going to fit a through bulkhead connector but will dispence with that idea and just run the cables through glands or gromets.

Thanks for the advise.

 

I think a futher upgrade of dash will involve a lot of sorting of the electrics under the scuttle.