Autosport Labs

I've had the MJLJ running for over 2 years now with no issues, but recently the engine has become harsh... Just checked the timing with the Jolt unplugged and I find the timing is jumping 9 degrees... not drifting around, but a jump and the same 9 degree jump at any revs. Most of the time it's at 19 degrees, then it'll jump back to 10 and then straight back to 19.

I have ruled out the EDIS 4 as I have a spare which does exactly the same thing. When I first installed it all I had a rock steady 10, so I'm thinking the bracket should still be fine, although I am going to make up a new bracket from heavier plate, but as the timing is jumping a steady 9 degrees I'm doubting it's the brackets either.

Could it be the VR sensor? it's the one bit I don't have spares of.

It sounds to me, as though its jumping between programmed spark and (10 degree) limp mode. I doubt it is the VR, because losing sync there would put your timing all over. I'd suspect the MJLJ or its wiring; at this age, a loose or tarnished connection could do it. Cleaning or wiggling the chips that plug in might bring it back for a while. If so, they need to be soldered instead. Does it run a straight 10 degrees with VR off? Bruce Roe

There is definately no problem with the Megajolt unit as it was disconnected and running ONLY on the EDIS. I have used 2 different EDIS4 units and got the same 9 degree jump... always 9 degrees... measured at idle and 3000 rpm... 9 degrees every time. With MJLJ connected I still get the 9 degree jump but from the programmed 14 degrees idle advance giving me 23 degrees at idle... not good.

Another thing I should be able rule out at this stage is my digital timing light. I should be able to borrow another one next week to double check, but I really don't think this is the issue as the car isn't behaving... all symptoms are it being over advanced... also when holding a steady 3000 rpm without the MJLJ, each time the timing jumped, the exhaust note changed slightly leading me to beleive the figures the timing light is giving me.

I wonder if its a coil pack issue or what plugs are you running?? Resistive ones?? Maybe getting the odd bit of interference from somewhere.

Is ypur triggerwheel solidly mounted or is it on a crankshaft damper?? If so what condition is the damper??

Ryan

using NGK AP7FS plugs in a 2.1 Pinto engine. Running Motorcraft 8mm silicone leads.

Trigger wheel is bolted to the front crank pulley which is a solid cast steel item so no chance of any movement there as it's located to the crank by a woodruff key.

Try changing your plugs to some equivalent resistive ones. I believe they are APR7FS. Its a good chance your getting interference from your spark plugs causing an erratic signal/operation.

This, i would suspect, is the problem but i do not gaurantee it. Cheaper than a replacement coil pack unless you already have a spare lying around.

The leads are resistive, would having resistive plugs not be too much? The PIP and SAW lines are shielded and the EDIS is 2 feet away from the plugs. I will certainly get some plugs and try it though.

Just because your trigger wheel is bolted securely in place that doesn't mean that it isn't eccentric enough to cause the EDIS module to resync. I don't know what your crank sensor bracket is like but I've seen alumnium ones wobbly sufficiently to confuse things.

trigger wheel is concentric... VR sensor brackets are aluminium. The thing is, when I first set all this up it was rock steady 10 degrees. I'll make up new brackets in the next few weeks from some stainless steel shet I have here. I should be able to fold the edges to give more rigidity.