Please help, dead disco

[xstriple]

Oh jeez, sick of this.
Took my '91 petrol disco down to local mech for an arse reami,,,,,I mean a RWC,,,OK, expected the bull****. Driving to get required tyres and at the lights she dies.
Turns over (quite strongly, but seems like too easily), got it home courtesy RACV and current checks are,
Has spark on 1,
Intermittent spark on 5,
Changed TPS,,(then rechanged),
Cleaned and inspected dizzy cap,
Fuel pump primes,
can see a fog of fuel when airflow sensor removed.

Would there be any reason to suspect ecu if indeed it has one?
Do the distributors fail like that?
Getting close to tether end ;(

[bee utey]

Rotor button or ignition module. If its the rotor button burnt through your fuel pump will continue to energise with cranking. If its the ignition module then the fuel pump will only prime with the key, not from cranking. The ignition is NOT controlled by the ECU, just a regular electronic dissy. The ECU gets its rotation signal from the negative side of the coil, white wire with a black stripe. Check all coil terminals are clean and tight. Check for spark at the coil lead, not just at a plug.

Rotor buttons can be replaced with XF Falcon ones, Bosch part no. GB864. Ignition modules can be replaced with Bosch BIM024 ones, see thread here:

http://www.aulro.com/afvb/technical-chatter/96950-lucas-ignition-amplifier-replacement-bosch-024-a.html

[xstriple]

Hey Bee, thanks, will try that. Can you tell me if a 3.9 dizzy would replace the 3.5 please? Are ignition modules known to fail and would it fail slowly, ie. limp through two sets of lights then just not fire?

[sheerluck]

Hey Bee, thanks, will try that. Can you tell me if a 3.9 dizzy would replace the 3.5 please? Are ignition modules known to fail and would it fail slowly, ie. limp through two sets of lights then just not fire?

The answer is a resounding yes to the second question, though I don't know about the first question.

[bee utey]

Hey Bee, thanks, will try that. 1. Can you tell me if a 3.9 dizzy would replace the 3.5 please? 2. Are ignition modules known to fail and would it fail slowly, ie. limp through two sets of lights then just not fire?
1. Dissys vary a bit so it depends on what year 3.9 the other dissy is out of. Connecting plugs change, oil pump drives are not fitted to later dissys etc. 3.9 engines were sold for nearly 10 years you know.
2. Modules can fail slowly or quickly, I've met both scenarios lots of times.

[xstriple]

Well there's another wasted flippin evening with a ****ing landrover. Got another module fitted it to my dizzy, no change. I guess I'll just keep buying stuff till it works. Coil next. Can I just get a gt40 or do I need a firkin special one of those too?

[bee utey]

Diagnosis mate. narrow down the problem. Just throwing new **** at the job until it works will cost you heaps and give you a migrane. You've got one of the simplest ignition systems on a modern vehicle anywhere, nothing on it is specialist stuff like a full coil pack system.

Have you tried another rotor button? Have you got a multimeter to test the dissy pickup resistance while you've got the module off? Have you tested for voltage at the coil with the key on? Where's your module from, is it a no-name brand or genuine? Spares are useful anyway.

Don't put on a points coil like a GT40, they won't work properly. A suitable electronic coil is a Bosch BIC290.

[xstriple]

The module was off a rangy, genuine. Im a bricky, what are these tests you speak of ;)???

[xstriple]

Please excuse my ignorance Bee, but I have another dizzy, set up with a pirahna ignition, would this be compatable with the efi and and tips on fitting? Cheers

[bee utey]

Please excuse my ignorance Bee, but I have another dizzy, set up with a pirahna ignition, would this be compatable with the efi and and tips on fitting? Cheers

It might work if you have the coil that came with the pirahna system. From memory they worked with standard points coils.

Anyways, you only need two important wires for the system to run. The white wire at the coil comes from the ignition switch and provides power for the coil AND the ignition module. Test it with a light bulb and a bit of wire to earth the globe. Earth means battery negative or clean metal on the engine or a bolt through metal on the body. An old indicator bulb and lamp socket makes an adequate test bulb. No light=no ignition+no injection.

Next most important wire is the white wire with a black stripe. This connects to the negative side of the coil and takes the ignition signal to the ECU. It is the only way the ECU knows the engine is turning. No signal=no injection.

Now a question, if you had a module off another dissy, did you try the whole distributor? Did you pull out the original dissy to change the module? Did you carefully texta mark the dissy so that it went in EXACTLY the same as it came out?

Finally the rotor button. If its burnt out you're not going to get spark to the plugs. Have you tried another button? You can test a rotor button by getting someone to crank the engine while you hold the coil lead with heavily insulated pliers. If you get a spark to metal you have working ignition. If you have the same strength spark to the centre of the rotor button you have a burnt through button.

[xstriple]

Yes I pulled the dizzy and swapped modules. I pulled out no 1 plug and earthed it to engine and got spark so I dont think rotor. Coil and/ or coil lead is my next port of call.

[xstriple]

Well, tested the coil,,,primary windings resistance was 1.9 ohms( Haymes have that at 1.2 ohms) and secondary 15.45k ohms( they have that at 3to4000ohms). So I guess that's the problem then.

[xstriple]

Success! Grand! Thanks all for your help!