No Spark!

General Topics for configuring, operating and tuning the Megajolt. Also see the <a href="http://www.autosportlabs.net/MJLJ_V4_Operation_Guide">Operation Guide</a>

Moderators: JeffC, rdoherty, stieg, brentp

Post Reply
nzgt6man
Posts: 0
Joined: Fri Jun 04, 2004 12:35 am

No Spark!

Post by nzgt6man »

Hi,

I'm having trouble getting my engine to run, even in "limp home mode" and there appears to be absolutely no spark as the engine doesn't even try to start. I've double checked my wiring and connections and these appear to be fine. I've tried swapping out the edis module for another one with the same result (EDIS 6). I'm starting to think it's the coil pack which I don't have a spare of.

Does anyone know how I can test the coil pack without substituting it for another? I want to be absolutely sure it is the coil pack, before I go and buy another, as the EDIS parts are very hard to come by in NZ and are therefore expensive. Could anything else cause it? Is it possible to test the VR sensor?

The good news is the MJLJ I've built seems to function as it should!

cheers,

Robert Proud
1967 GT6 mk1

Paratime
Posts: 0
Joined: Sat Apr 17, 2004 12:47 am

Light my Fire!

Post by Paratime »

OK, regrettably, there is no really simple way to test a coil. I don't know your level of test equipment, or expertise, but I'll try to list the simplest tests I know.

1) if you have an ohm meter, the secondary resistance should be around 12Kohms from one end of the coil to the other. opposite ends will be numbered for paired cylinders. ex. the firing order for most 4 cyl cars is 1342 so, 1-4 are pairs, as are 3-2. there are several 6 cyl orders. a common one is 165432 it would be paired 1-4 6-3 5-2.

all other measurements (like 1-6 or 2-4) should be open circuits (or infinite ohms)

2) the primary resistance should be around .5 ohm from the 12volt pin to the other primary pins (these are the clip on wire connector).

If you're OK this far, we'll move on to a coil output test. Sadly, this is rather involved, and requires some parts you probably don't have. Luckily, they are not too expensive.

A coil produces high voltage when you apply 12 volts to the 12 volt pin, and ground to one of the other primary pins: then break the circuit with a spark suppression circuit. just momentarily touching and removing a ground wire will not produce the high voltage spark, because the primary flyback voltage will bridge the gap, and bleed off the energy. This is why older engines used breaker points AND a condenser (or capacitor, as they are called now)

SO....
what you have to do is find a points and condenser for some old car. pre 70's V8 GM's have a nice setup, the points and condenser are all one piece, making hookup a breeze. Don't know what the NZ availability is....

You have to attach the part of the points that screw down to ground, and the center electrode point (usually a small screw by the spring) to one of the the primary pins, and 12 volts to the 12 volt pin. The capacitor also connects from the primary pin the points are on to ground.

Now you need to connect the spark plug wires to all the towers, and tape the metal parts of the spark plugs together of all the coil pairs (ex 1-4).

NOW.... When you manually open and close the points, a high voltage spark will jump across both the plugs on that coil pair.

Easy? No, I guess not. If this is too confusing, I will draw up this set up and post it on my pictures page.

Tomorrow I'll go over how to test the pickup. (sightly easier)

brentp
Site Admin
Posts: 6275
Joined: Wed Jan 24, 2007 6:36 am

check VR sensor polarity

Post by brentp »

Hi,

Check the VR sensor polarity. it will only work wired in one direction. Might be an easy fix!

Brent
Brent Picasso
CEO and Founder, Autosport Labs
Facebook | Twitter

nzgt6man
Posts: 0
Joined: Fri Jun 04, 2004 12:35 am

No spark!

Post by nzgt6man »

Thanks for all the info regarding testing the coil etc. I'll double check my wiring and test the coil. I've already checked the resistance of the coil, the secondary circuit is 14.5 ohms and the primary is about .5 ohms so I'm guessing it's ok but I'll check it for output just the same. I own an "older car" (67 GT6) so I have lots of points and condensors lying around.

I don't think my wiring is wrong as I removed the whole wiring loom from the car I got my EDIS 6 from and untaped it so I don't have any joins and the wires match up with the connector to the EDIS unit, but i'll check it anyway.

One thing I noticed last night was that the gap between the vr sensor and the wheel might be a bit big, its probably between 2 and 3mm and I believe it should be about 1mm, so that might be the culprit. I've only got about 30mm between the radiator and the pulley so it's really awkward adjusting and measuring things.

I probably should post a picture of my pulley adapter I've made, as it allows 360 degree ajustment of a standard toothed trigger ring from an escort. This made setting the timing much easier when there's not much room. I did have it welded on, but decided to do it "properly".

Thanks again for the info I'll let you know how i get on,

Rgds,

Robert Proud

Paratime
Posts: 0
Joined: Sat Apr 17, 2004 12:47 am

Great PickUp line!

Post by Paratime »

The pickup can be quick tested with an ohm meter. It should be around 600 ohms.

To fully test the pickup, you need an oscilloscope, and monitor the output wave when it's running.

You can get a good idea if it's working, though, if you have a milliamp-meter. Set the meter to .5mA (or it's most sensitive if it won't go that low) attach the leads to the two sensor terminals, and repeatedly touch the sensor to the toothed wheel (or other convenient steel object) you should get positive and negative pulses of current. An analog meter shows this best (cheapies at RadioShack are ~$20) but you can still see it on a digital. If the meter has 'Max Hold' it will show it best.

Paratime
Posts: 0
Joined: Sat Apr 17, 2004 12:47 am

Que?

Post by Paratime »

Your secondary should be 14.5 Kohms, or 14,500 ohms. If it's 14.5 ohms, then it's no good. :(

nzgt6man
Posts: 0
Joined: Fri Jun 04, 2004 12:35 am

Was no spark, now spark but spitting back

Post by nzgt6man »

Whoops abit of a typo there, the secondary resistance is 14.5 k ohms not 14.5 ohms. I've tested the coil and it seems to be fine, I get nice healthy blue sparks. Adjusted the VR sensor gap and I now get sparks BUT I'm getting spitting back thru the inlet manifold which is obviously a timing issue.

The wheel is setup correctly (60 btdc) so that leaves the order of the plug leads or coil firing order. My firing order is 1 5 3 6 2 4, so I've got plugs 1 and 6 paired, 5 and 2 paired and 3 and 4 paired which is correct as far as I can see. so the only other thing it can be is the order the EDIS module fires the coils in.

Of course my coil pack doesn't have numbered towers or coils so does anyone know what order the coils are in, on an edis 6 coil pack?

I've assumed that the rh side pairing (looking from the connector side) is coil 1 the middle pair coil2 and the end pair coil 3 but i'm begining to wonder now. The reason for my assumption is the order the wires go into the plug, ie coil one wire from the edis module goes into the rh side of the plug.

Rgds,

Robert Proud

brentp
Site Admin
Posts: 6275
Joined: Wed Jan 24, 2007 6:36 am

Sounds like you're getting cl

Post by brentp »

Sounds like you're getting closer!

would it be possible to inspect a running EDIS 6 vehicle to see how the spark plugs are configured?
Brent Picasso
CEO and Founder, Autosport Labs
Facebook | Twitter

nzgt6man
Posts: 0
Joined: Fri Jun 04, 2004 12:35 am

She Runs

Post by nzgt6man »

Finally I've got the car running. It would seem that the wiring diagrams I've seen on the net are wrong when it comes to wiring an EDIS 6 module. On all the diagrams I've seen, wires 10 11 and 12 are shown as going to coils 1, 2 and 3 respectively. It would seem that wire 11 actually goes to coil 3 and wire 12 is for coil 2.

On the coil pack, coil 3 is the CENTRE coil, so looking at the pack from the connector side, coil 1 is the rh coil, coil 2 is the lh coil and coil 3 is in the centre. I ended up going to my Ford dealer and talking to their auto electrician who sorted it out straight away.

car runs great now, can't wait to get it on the dyno to nail down the timing properly. I'm running a map thats a clone of my distributor at the moment, but as my engine is very modified I'm sure we can extract a bit more from it with this setup. Thanks everyone for all the help,

Rgds,

Robert Proud

Post Reply