Petrol/Electrical problem pls help!
Hi All,
This post refers to a problem with a 460 280 petrol/auto 1982 vintage.
Just getting the offroader ready for a competition tomorrow and of course left all the hard jobs till the last minute. Got them all done and had loaded it on the trailer with the engine running when I noticed smoke from the engine bay on the opposite of the exhaust.
Bonnet was up and I thought it could be the winch wiring, no all well, switched the engine off and investigated further.
This is where it gets complicated.
On the passenger side(engine bay) between the battery and the ignition coil there is a Alu box/brain. Underneath this box attached on to the inner wing are two ceramic like blocks like resistors/or fuses. The upper block has 2 light wires entering it(white with a thin green stripe) and 2 wires leaving it (red with a thin black stripe).
Each of these wires enter the other block below the upper one. My problem is this(upper block) when the vehicle is running is getting dangerously red hot, hence the smoke. None of the wires in or out has burned or melted or gotton unreasonably hot.
These wires come from the dash/loom and after going through the blocks return to the dash/loom again.
When the engine is running and reved it sounds like a misfire/backfire or an incorect firing sequence, broken lead or bad plug, that kind of thing.
When I disconnect the wire coming out of this upper block and restart the engine it restarts cleanly no problem then cuts out. If you restart the engine and rev it, it revs cleanly no backfire or coughing/spluttering then it stops/cuts out.
What is this block?
What is it called?
Anybody have a partnumber/ price?
What actually is its function?
Anyone have one for sale new or used?
Is this my problem or is it a stuck relay or something somewhere else?
Sorry for the discription and no photos. I know its difficult to visualise what part exactly I am talking about but if you can I would appreciate your help.
Regards,
Mike
PS Checked the engine bay of a 230 petrol and this twin block unit isnt there.
Hi Mike, yes they are some sort of ballast or resistors for the injection system. Can't look untill this evening but if no one else chirps up I'll look them up on the epc for you. The car will probably still run but might be a bit rough.
Hi Mike it may be an earthing continuity problem.check the bonding leads between the engine and the body for breaks or corrosion.....and the earthing point behind the dash panel to the right hand side of the steering column as you sit behind the steering wheel......
Thy are ballast resistors for the ignition sytem two different resistences, both necessary. The coil doesn't operate at 12v but some less. They certainly are important. They can operate quite hot too as the coil current passes through them both. Check the area is free from oil and crud and the electrical connections are clean. Are you running the correct coil?
Right, thanks again for the help people and sorry it has taken so long to get back.
Took the dash out and checked all earths and connections and did the wiper linkages while in there.
Didn't cure my electrical problem though.
Next switched the wires on the ballast resistors, no change.
Next took the ignition coil from another G and swapped that. Eureka problem more or less solved.
Did event on that weekend sat and sun and everything went fine apart from snapping my front steering linkage about a mile from any usable roadway in the trees but thats another story for a different section.
Thanks again, I was at my wits end at the time you're help was much appreciated.
Regards,
Mike
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Hi Guys,
Thanks for the replies to date.
They have never been noticably hot before atleast not way too hot to touch, hot enough to melt through winch cable insulation and this only the top one.
The coil has not been touched and the vehicle has run fine in the recent past. I will check the earths and clean all connections today.
Are they both the same(the ceramic blocks) and can I switch them around to see if the bottom one now gets hot or are they a different size voltage??
If I run the vehicle as is, it misfires and backfires if reved up/ driven on. At idle it sounds OK and the misfire is barely decernable. Its the fear of a fire I am most anxious about as today I was to be in the middle of a forest. Decided not to attend for obvious reasons.
Thanks again for your help in trying to solve this. I will report back later today.
Regards,
Mike