Reply With QuoteVoltage sounds fine. I would try running a new power wire to the ignition coil and Lumenition direct from the ignition switch before replacing any other parts. The symptoms sound much like a loose connector getting hot and disconnecting.
Master
SupporterGood evening all,
I am seeking some advice on fixing two strange problems with my landy - 1984 110 V8, carby, dual fuel, lumenition electronic ignition. It had a erratic and sharp misfire under load when the motor got warm when running on LPG so i tried the following:
- new plugs - Bosch WR7DC+ gapped to 28 thou
- new leads - Bosch inductive core
- new cap - lucas
- new rotor button - facet
- tried spare lumention modules
- tried spare optronic light
- checked vacuum hoses
- tried many coils - some that require wiring to ballast resistor and some that do not - i make sure the lumenition module is always getting over 3 ohms of resistance.
- cleaned as many electrical connections that i could find
- tried many LPG mixtures
- advanced and retarded timing
Nothing helped, and then the truck started to shut down completely (both on LPG and petrol). Sometimes coming back to life a second later, sometimes not for 40 min. No spark was found coming from any of the coils, but all other electrics on the car work fine. After a while spark would return and the car would run. The coils, both resistor and non resistor, do seem to be getting quite hot.
Could the problem be related to output from the alternator/regulator? 14 v at idle, 13.5 with headlights. I cannot measure the amps. Is it worth looking at the wiring from the starter solenoid to ignition?
Many thanks,
Edward
AT REST
Voltage sounds fine. I would try running a new power wire to the ignition coil and Lumenition direct from the ignition switch before replacing any other parts. The symptoms sound much like a loose connector getting hot and disconnecting.
Fossicker
I had a similar problem once in a old Mercedes. It turns out that a ground wire was broken inside the rubber. When it got hot the rubber stretched a little and the circuit opened up. When it cooled down the rubber shrank, the wires connected and all was fine. Took forever to diagnose.
Master
SupporterThank you Bee Utey. I did not have much time to work on the truck today, but I will do what you suggested tomorrow and i'll report back. I did try starting it on petrol today and it would not. I removed the wire that runs from the negative side of the coil to the gas safety switch ('pulse' connection). The truck started immediately after. I cannot figure out why this could have helped, especially considering that i was on petrol. Perhaps it was just coincidence. I will give it a proper test drive tomorrow.Originally Posted by bee utey
Edward
AT REST
It's also possible that the original LR power wire crimp terminal is too loose, met that plenty of times before. Those terminals should not be loose enough to move without some force. Carefully squash the connector/s with pliers so they take some effort to get on. Failing that fit a new fully insulated crimp terminal to the end of the wire. The action of pushing on a tight connector helps scrape the oxide off the terminal on the coil.
Master
SupporterHi bee utey and rayhyland. We managed to fix the truck today. Replaced the power wire between the ignition and coil as suggested and the misfire was fixed, but the truck continued to cut out when warm. Replaced our spare coil with another spare and it has been fine since! Thank you again for your help.
Edward
Master
SupporterTruck cut out completely again this morning. Back to the drawing board!
AT REST
I had a Lumenition once, it broke down way too early for my taste. Find yourself a clean D1 distributor and wire it for a Bosch module. Much less troublesome and easier to get spares for.
Master
SupporterThe truck would not start this morning. I fully bypassed the ignition barrel switch to make sure that it was not shorting within the switch. No start. I bypassed the petrol/gas selector switch. No start. I put a spare module on. No start. Spare coil lead. No start. The spark at the coil lead is intermittent - sometimes strong, sometimes weak, sometimes non-existent. It eventually started and ran fine. I have a new coil which i might try (even though i tried it the other night and the truck was missing. Hopefully it was the old coil wire causing the miss, and not the new coil - Bosch SU12). If that doesn't work i'll run a power wire straight from battery to ignition in case there is a break in the fuse box (even though when the truck cuts out all the accessories still work fine).
Thank you for your suggestion bee utey. I may look into that.
Edward
Master
SupporterGood afternoon all,
I have been driving the truck for a few days and it has not cut out or misfired. Replaced the optronic light with an old spare and hasn't cut out since. The misfire still remained. To me it felt like a plug was breaking down. I whipped out the brand new Bosch WR7DC+ plugs (gapped to 0.7 mm) and put in an old set of bosch plugs (which were misfiring only very slightly when i had removed them). The bad misfire is now gone (only the minor misfire that the old plugs were making still remains). Must have just got a dud plug i guess. (They all measure the same ohms when cold though). I will look into getting a set of the NGK BPR6ES plugs that i used to use without too many problems.
Thank you again for your help.
Edward
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