Ignition problem

[russgregg]

Hi guys, hoping some of you knowledgeable folks might be able to help with a diagnosis. I've fitted the mechanical parts from my 86 mk1 into a custom made buggy frame, (http://www.imoc.co.uk/forums/viewtopic.php?t=168209), but now that completing the final assembly I went to fire the engine today and i'm having some problems getting a spark. I'm thinking that if I describe the problem somebody out there who knows the system better than me might be able to point me in the right direction.

I have had the engine running while mounted in the spaceframe but took it out for final welding and paint and this is the first time I've tried to fire it since.

I have tweaked the wiring a little, (moved the battery to the front and removed the key/barrel and replaced with a series of toggles and a push-button start), but i'm fairly happy that that I've reconnected everything where it should be and haven't done anything very stupid.

The engine is spinning nicely and I have fuel being delivered but I have only got a very occasional spark. The problem seems to be across all cylinders, no cylinder is sparking correctly but I have seen sparks on at least 2 of the 4. The spark looks reasonably strong when it does appear but just not frequent enough.

I removed the dizzy cap and all looks fine, so I just cleaned it up a little and re-installed, all the HT leads are in the right places and the 12v plugs are connected and appear ok.

I'm wondering about a coil/igniter problem but I don't know the system well enough to know what other possible causes that I maybe should be considering.

Any suggestions welcome.

Thanks

Russ

[kaiowas]

How are your earths? The 4 age can be a bit picky if they're not all connected properly. Wondering whether you've forgotten to reconnect one after painting or just painted over where one should be

[russgregg]

Kaiowas, I think the earths are pretty good. They're new and clean

Thanks

[PW@Woodsport]

Remove your coilpack/ignitor, either grind the paint off and make sure the bracket is getting a true ground to the chassis, or run a separate earth strap from the bracket to ground.

[russgregg]

Thanks Paul, i'll maybe run a new strap just to be sure.

[PW@Woodsport]

You may find the issue may be between the coilpack/amp and bracket rather than bracket to chassis, they rust badly between those components so i'd advise stripping them off the bracket too.

[russgregg]

Got a chance to do some digging round the buggy aver the weekend and I did find a few things. 2 of the spark plugs were in sorry shape with cracks in the ceramics which wouldn't be helping but that's not my primary problem.

I went through all the BGB troubleshooting steps and the only thing that wasn't in spec was the primary coil resistance (0.9 ohms as opposed to between 0.52-0.64 ohms)

When I did the spark test with the main coil-distributor lead I sometimes got an initial spark then nothing after or sometimes just nothing at all

I did run a new earth strap to the coil bracket but no difference there.

Next plan is a new coil/ignite and see what that does unless anybody has a different suggestion?

R

[aw11rally]

Try a different coil. I'm sure many will disagree due to resistance and dwell etc etc but any old coil should do. My Range Rover Classic ran much better with an AW11 coil than with the crusty old lucas one is came with.

Just worth a try before you spend any money or time on it. If you've got any coils knocking around that is.

[russgregg]

Coincidentally I had a couple of spare coils which just happened to be from an old 3.5 V8 classic rangie which I did try but no change i'm afraid.

Thanks

[russgregg]

Just to close this out as I know it's a pain searching old posts looking for a solution to a problem that just stops in mid flow.

Problem turned out to be a bad earth connection onto the intake manifold, was belling through fine but when the engine cranked the voltage was dropping too low to give a proper spark.

On the plus side I now have lots of spare ignition components.

Thanks all

Russ