Megajolt installed, misfiring (1968 Mini, 1275cc) FIXED

[68 deluxe]

Car: 1968 Morris Mini Deluxe
Engine: 1275cc
Carb: HIF44
MAPs tried: KLAS' 1275 & Aldon Yellow

Hi All,

Have megajolt system installed, seems to be working ok, except no matter which map I run it always misfires and backfires. Have tried offsetting the advance angle by +/- 5 degrees as I though my wheel might be a few degrees out but still no luck..

Don't have access to a timing light at the moment to check if Megjolt is actually advancing ignition.. can get one tomorrow

Please see below pics of wheel/VR installation ...

First image shows vertical alignment of sensor vs wheel:


Second image shows placement of teeth while engine is at TDC (checked via flywheel mark in viewing hole):


There is less than 1mm gap between sensor and trigger wheel..

Does the sensor wheel alignment look ok?
Is there anything I can try to get rid of the misfire? It's driving horribly!

Thanks,

Tim in Australia.

[Spockie-Tech]

Cant see your mounting bracket clearly in those photos, but from what I can see it looks like it could be a bit flexy.

Ive seen on the dyno how at certain RPMs and loads, what looks like a fairly solid piece of steel can start resonating and twanging about like a tuning fork..
You usually need to get some sort of right-angle gusset or strut on the bracket to minimise flexing on any axis.

Some other possible causes of misfiring are
Interference from an unshielded VR sensor wire picking up noise from the high tension leads if they are close,
The coilpacks/HT leads being too close to the EDIS module and glitching it.
Faulty Spark Leads (use a meter to check their resistance while flexing them about, or try replacing them if youve done everything else)
Fouled Plugs
Weak Coil Packs
Fuel Mixture problems rather than ignition (need an Wideband Oxygen / EGO gauge to check),
... or you can do the old-fashioned "hard ignition cut" tuning technique.
... Wind the car up to the point where it misfires, turn the key off at that point, *then* take your foot off the accelerator, roll to a stop, and pull some plugs to check their color to indicate lean or rich mixtures.

While its tempting to first blame/look at the "unusual" parts of a Megajolt ignition (like the sensor, module etc), remember that Distributor cars misfire too, and usually for the same reasons that an EDIS misfires..

So far in my experience, Its usually not the Timing system (EDIS/Megajolt) that is at fault, but your spark generation and delivery system. Unless youve got wacky entries in your MAP, but even than it doesnt usually result in a misfire, so much as a flat/lazy or pinging spot in the rpm range.

[NITROPIXIE]

Are you using resistive plugs??? This can cause running problems on some cars??

What grounds are you using?? The same for EDIS and megajolt?? Do you have a good engine ground??

I would also double check your wiring from EDIS to coil pack as it sounds like this a little, from experience .

Also check the ignition leads are going to the correct cylinder and are in good operational condition. Basic I know, but just double check.

The gap of your VR sensor looks fine, not sure on your mounting bracket though, could do with a better picture of it.

Otherwise as Spockie Tech says.

Also something else to consider is that megajolt sometimes requires a richer fuel mixture. So this may not be a megajolt issue but has exaggerated a fuel issue. If no problems can be found and you can confirm timing with a timing light then have your fuelling checked. I always find the SPI2 map as a good general to start with and i have the same setup as you.

[68 deluxe]

thanks all..

VR mount is solid, there is a gusset at the bottom. It's sold as part of a kit, and has been used by others without issue
coil-to-EDIS leads are all decent gauge wire.
VR/Pip/Saw are all shielded and grounded at same point as EDIS and MJLJ. paint scratched away to ensure good grounding

Plugs are non-resistive
Leads are the old leads that were on the dissy set up (which worked fine then), will try the leads that came with the EDIS from USA.

Thanks for the help, will let you know how it goes!

Tim.

[NITROPIXIE]

The leads from your dizzy setup aren't the correct connector fitting for a ford coil pack, so chances are you have a loose/bad connection here. And your spark plugs should ideally be resistive types as it helps suppress noise.

Ryan

[BRUCEROE]

As a sanity test, I suggest you remove the plugs and the injector wires (or you have a carb?). Ground the plug wires so that the ign can operate without damage, and disconnect the MJLJ for EDIS limp mode. Spin the engine with the starter and use an inductive pickup timing light to check the position of timing marks for EVERY cylinder. Chalk about where the cylinders other than #1 ought to show up.

If the spark timing is jumping all over, look for bad parts. If the marks are steady but in the wrong position, work on your wheel & coil wiring setup. If you have every plug spark at the right position, you are chasing an intermittent problem. Get that fixed in limp mode, then add MJLJ. Bruce Roe

[68 deluxe]

woohoo!

It did turn out to be a naff bracket. Had to slot the bracket mount holes so the bracket sat lower, and redrill the two VR sensor holes lower and around a bit, and now it sits right on tooth 9. It was about 8 degrees off!! (For clarification, bracket was bought as a kit which was meant to bolt straight on to the mini engine and line up perfectly with the also supplied trigger wheel which also bolts straight on to the standard 1275 crank harmonic dampener pulley. Perhaps my pulley holes were different to others? Who knows.

In the mean time I had tried new plug leads (with correct clip on connectors), with no change.

Easy mounting tip for VR sensor. Get bracket in about the right position, then let the magnet of the VR sensor hold it to tooth 9 (and stabilise the bottom of the VR with double sided tape to the mounting bracket), mark holes in right position, remove and drill. worked perfectly.

To all the people who ask if leading edge/trailing edge needs to be at the sensor when engine is at TDC, in my experience, the middle of the tooth needs to be in the middle of the sensor @ TDC, as shown in the diagram in the installation instructions.

Thanks all for help and listening and understanding of noobness

[NITROPIXIE]

Glad you got it sorted fella. Now you have a working car would you mind putting it in the powered by section so we can all have a look please. It would be appreciated