30 replies to this topic

[Heath]

Got a problem with ignition on the car I just bought. UC, 202 with VK-style electronic ignition.

 

Car was fine two weeks ago when I picked it up but then the tacho (four cylinder sports dash which was over-reading by 50%) stopped working and I've been stuck with this problem since. Driven the car a few times in the last week and it's happened every time.

 

The spark just breaks down, lots! It is not strictly load-dependant but it is obviously related. Sometimes it will idle for minutes at a time, sometimes it will stop after a few seconds. Generally when you take off it starts to break down as the load increases (as you let the clutch out), like it falls over and then fires etc. has backfired a few times when it stumbles heaps.

 

Free revving seems to be normally okay, but sometimes stumbles as you start to open it up. Trying to rev it under load it just falls over.

 

Sitting at about 90km/h, it stumbles every few seconds I guess exercising the lash in the diff, the extra load of trying to do 100km/h normally results in violent stumbling at least once a second but it isn't consistent in its frequency. It becomes very obvious when you're cruising along at speed that when it starts missing, the tacho jumps up from nothing to 1000rpm-2000rpm and then drops back down. It displays nothing when the car isn't missing.

 

The ign module/dizzy is wired to the +ve and -ve of the coil. The -ve of the coil also has a wire going into the loom (presumably just goes to the tacho) but even if I disconnect that the problem doesn't seem to change? The +ve is bridged from a pink connection on the firewall (I think that's the easy way to get 12V without a relay) and also has a little condensor connected to the +ve.

 

So I've gapped the plugs from ~.033" to .030" to see if that would reduce the load enough to make the problem more manageable, not sure if it made any measureable difference. I've checked a few wire connections, tried isolating the tacho, tightened the ignition module terminals and cleaned the screw threads.

 

What do you think is causing it? I've got some spare bits that I can try on but I'm not sure what to start with.

 

Appreciate any feedback!

Edited by Heath, 28 June 2013 - 08:06 PM.

[Heath]

My R30 Distributor rotor button in my H230 Cedric split down the bore and went loose on the shaft too, although the symptoms were different. Will double check it tomorrow!

Edited by Heath, 28 June 2013 - 09:42 PM.

[hanra]

Is the coil supply wire still the original resistance wire as per points dizzy? Might be low voltage at the coil?

[rexy]

How regular does the spark timing look with a timing light?
In the absence of an obvious defect swapping dizzys is the first thing I would try. Presumably you have a spare?

[S pack]

I suspect if the yellow +12v and pink (1.8 ohm) resistance wire are bridged at the bulkhead connector (as per factory wiring diagrams) then you are still only feeding 7 or whatever volts to the coil. Use a multimeter to check the voltage to the coil with the ignition in the ON position.

 

Probably also get rid of the noise suppression capacitor off the coil.

[Heath]

My timing light broke and I haven't replaced it yet lol.

 

I thought the bridging the pink and yellow wires on the firewall was 'the way you get 12V ignition without a relay', not just the standard configuration. My memory is a bit fuzzy! But I do remember running 9V with HEI on my old LX with no real adverse symptoms (not that I am ruling that out as a source of the problem)

 

Noise suppression capacitor is not worth having? Or just worth isolating for testing purposes?

[S pack]

The wires would need to be bridged at the ignition switch wiring connector to eliminate the voltage drop caused by the resistance wire.

 

Disconnect the noise suppression capacitor for testing purposes to start with. Remove it completely if it's not needed.

 

I'm suspecting you could have a failing coil.

[Heath]

I was looking at the wiring incorrectly. The power for the +ve of the coil comes from two sources: the purple wire on the firewall plug and a non standard (black) wire from a 12V w/ ignition source from a bay on the fuse panel. This bay is bottom left and has pink wires going to and from it, and the fuse is blowing.

When the fuse is not blown, the coil gets 12V
When the fuse has blown, the coil is back to ~7V

Edited by Heath, 29 June 2013 - 02:15 PM.

[Heath]

The yellow and pink bridge in the firewall plug exactly like you said S pack, and the yellow ignition wire that comes out the other side has been REPLACED with a purple wire.

[hanra]

So basically you don't have full 12v at the coil then.

[Heath]

Kinda... just realised If I disconnect the aftermarket 12V wire from the fuse box so that the coil is just powered by the yellow-pink wire (which happens to be purple), the car gets 12V at the ignition AND it runs like a dream for 30sec until the immobiliser cuts in. 

 

I'm thinking it's alarm-related but it's hard to figure out how this thing is wired in.

[S pack]

If the car has an immobiliser then you need to follow the yellow and pink wires from the ignition switch connector to the bulkhead wiring connector to find where the immobiliser wiring has been connected in to enable interruption of the ignition circuit. If the pink and/or yellow wires are intact then the alarm may not incorporate a proper immobiliser, instead it may just be the starter motor that gets disabled.

[Heath]

Yeah I will have to pull the dash out and have a look into it.

[hanra]

Just drop the steering colum to access te IGN switch.

[Heath]

Well I'm gonna confidently say there's nothing wrong with the coil or the dizzy. It's just a supply problem. The aftermarket 12V wire comes from a circuit that has an intermittent short, and when that shorts, the ignition breaks down. There are no diodes so I guess the energy just runs in the other direction.

 

Today I had the steering column dropped out, dash centre and instrument cluster out, chasing wires etc and pulling apart every plug I could find, working with LH wiring diagrams which aren't perfect.

 

Basically it seems that there was a dead short in the electric choke (34ADM Weber) which was on the same IGN 12V circuit which the gauges run off etc, isolating that made the problem a lot better but it's still there. And because it's intermittent, I can't just easily check it by using a test light when the car is sitting still. It must be a loose wire or similar because going on the brakes and sometimes around corners makes it worse.

 

I have wired a globe in across the fuse box of the bay that is giving me all the grief, so when it shorts the globe lights up and it's very clear when I'm driving around.

 

What a bastard.

[rodomo]

Check your earths.

[S pack]

Heath

Car was fine two weeks ago when I picked it up but then the tacho (four cylinder sports dash which was over-reading by 50%) stopped working and I've been stuck with this problem since. Driven the car a few times in the last week and it's happened every time.

 

It becomes very obvious when you're cruising along at speed that when it starts missing, the tacho jumps up from nothing to 1000rpm-2000rpm and then drops back down. It displays nothing when the car isn't missing.

 

 

Hmmm, I wonder how the faulty tachometer fits into the scheme of things?

[yel327]

Heath, bridge the yellow and pink (start and run) wires at the ignition switch. This will give you 12V at the coil. Remove the otehr cr@p at the coil and run 2 x wires from the firewall plug (pink and yellow) to the coil. Discinnect the tacho wire (should be brown) from the coil. Unless there is an immobilser cut in somewhere this should work. 

[S pack]

Heath, bridge the yellow and pink (start and run) wires at the ignition switch. This will give you 12V at the coil. Remove the otehr cr@p at the coil and run 2 x wires from the firewall plug (pink and yellow) to the coil. Discinnect the tacho wire (should be brown) from the coil. Unless there is an immobilser cut in somewhere this should work. 

Agree, except you don't need a pink and yellow from the bulkhead wiring connector to the coil. The factory wiring is a single yellow wire to the coil.

Personally I would completely disconnect the existing yellow and pink wiring and run a new suitable gauge wire, bridged at the ignition switch pink and yellow terminals, through to the bulkhead wiring connector. This leaves the original wiring intact if a return to a points distributor is desired.

[yel327]

That's right, on these the start and run wires actually bridge again at the plug, I was thinking older stuff I think. You can use the existing wiring though, just get the connectors out of the ignition switch plug and solder a link bewteen them, and put them back in. The link can be unsoldered at a later date if desired.

[hanra]

Heath just so your aware, the two wires that come from the IGN switch to the bulkhead, the point of them is...

 

The pink wire is the resistance wire, its job is to lower the voltage to the coil to prolong the life of the points when the IGN switch is in the ON position when the engine is running.

 

The yellow wire's job is to provide a full 12v to the coil when the IGN switch is in the START position only.

 

If you remove the pink wire and run a jumper from the yellow wire to where the pink wire was on the IGN switch plug, you will now have 12v during crank and 12v during IGN ON positions.

 

Keep in mind you cant just cut the pink wire near the plug and solder a jumper onto it. It is not normal copper wire and solder will not stick to it. You need to open up the spade terminal and remove the pink wire altogether and fit a new copper wire jumper.

Edited by hanra, 01 July 2013 - 03:22 PM.

[S pack]

If you remove the pink wire and run a jumper from the yellow wire to where the pink wire was on the IGN switch plug, you will now have 12v during crank and 12v during IGN ON positions.

If you do as Brad has suggested, you will have to insulate the exposed female spade connector on the pink wire that is removed from the ign switch wiring connector as it will always be live when the ignition is in the START and ON positions. Power will still be fed to the pink wire from it's connection to the yellow wire at the bulkhead connector.

[hanra]

Sorry Dave, I may not have been clear enough. I removed both female spade terminals from the plastic plug (yellow and pink), open the spade terminals up, remove the pink wire entirely, fit a new jumper, re-crimp or solder the new jumper to the ex-pink female spade, then add the new jumper into the yellow female spade terminal. I then removed the pink wire from the bulkhead connector also. Just the singular yellow wire is left.

 

Thats what I did anyways, kept things neat and tidy. I am running a Pertronix electronic module as I couldnt bear to run a set of points.... even though I should have for originality's sake....

Edited by hanra, 01 July 2013 - 03:44 PM.

[S pack]

Sorry Dave, I may not have been clear enough. I removed both female spade terminals from the plastic plug (yellow and pink), open the spade terminals up, remove the pink wire entirely, fit a new jumper, re-crimp or solder the new jumper to the ex-pink female spade, then add the new jumper into the yellow female spade terminal. I then removed the pink wire from the bulkhead connector also. Just the singular yellow wire is left.

 

Thats what I did anyways, kept things neat and tidy. I am running a Pertronix electronic module as I couldnt bear to run a set of points.... even though I should have for originality's sake....

Ahhh, OK. Yeah sounded like you hadn't thought about also disconnecting the pink wire at the bulkhead connector.

 

Cheers

Dave.