The V8 Owners Forum -

Hello.
My trustfully Range Rover 3,9 Efi (1992 model) has stranded in my driveway.
As mentioned in another thread it has a minor problem with the head gasket. A while ago it startet running uneven/cutting out shortly after being started, perhaps 2km. It would continue for another 2-3 km's an then disappear again. Sometimes it gelt like not running even or lacking power. I reckoned it to be the head gasket problems.
Then it began not firing when turning the key. Only after 3 attempts did the engine fire up, and then it ran as afore mentioned. After a while it took a lot of attempts cranking the engine before it fired up, and eventually when I was about to drive it out of my garage, it took a fair amount of attempts, before it fired up with the throttle part opened. I drove it outside in my driveway and stopped the engine.
When I tried to start it again, it wouldn't fire up.
I checked the spark from the coil by unplugging the main lead from the distributor. "Small" yellow sparks were present. I checked for gasoline reaching the fuel rail, it did.
It's been standing since 2005, so I suspected low fuel pressure and replaced the fuel filter. No change. I then replaced the pump, which had collected some dirt in the plastic container. No change.
With the ignition lead placed on the inner wing close to a wrench key, it initially didn't spark, but then suddenly did. I reconnected the ignition lead, but it wouldn't fire up.
I then changed the ignition amplifier on the distributor - and used plenty of the liquid gasket stuff. Now it doesn't spark at all. I tried another lead cable - no difference.
What could be wrong? I suspect the coil, a small asain fabricate thingy. Or could it be the ignition switch? The engine cranks fine.
I changed the oil to 25w50 recently, and when cold the oil pressure light would be on for a "short" moment when fired up. Is there a relay that cuts off the ignition with no oil pressure? The light goes off immediately when cranking the engine though, and it did spark a little earlier.

I have tried to apply logics, but I haven't measured the voltage on the coil yet, as I'm a DIY without much experience in - but great suspicion towards - the electrics.

Do you actually mean liquid gasket? That could act as an insulator, and the amp gets its ground via the plate on the back contacting the dizzy body.

The correct stuff to use is thermal paste - to improve the heat conduction.

Lasse Kristensen wrote:I then changed the ignition amplifier on the distributor - and used plenty of the liquid gasket stuff. Now it doesn't spark at all. I tried another lead cable - no difference.

Hello Lasse, As Dave says, that cannot be correct.

The amplifier must be mounted to the dissy without any gasket stuff, but metal to metal with a smear of thermal paste ensuring maximum thermal conductivity, to prevent the amplifier overheating.

Here is a complete Ignition Test program:

TESTNG IGNITION COMPONENTS - BACK TO BASICS

The circuit represents BOTH the system where the amplifier is mounted in an aluminium housing behind the coil AND where it is mounted on the side of the distributor. The effective electrics are the same, just the physical locations of components differ.



Be sure the earths and the wiring from the ignition switch through to the coil, distibutor and amplifier module are pretty much the same as shown.

Getting Started

o Reasons for testing the ignition system are a proven loss of sparks at the spark plugs, or weak/intermittent sparks causing misfiring.

o To proceed, separate the Low and High Tension circuits to find out immediately which circuit is faulty, then persue the fault condition in either circuit according to the results of some logical tests.

o Remove the king lead from the distributor, connect it to a good spark plug and lay the plug on the engine somewhere.

o Switch on the ignition and crank the engine.

o Is there a fat spark at the spark plug.

o If Yes - then the problems are downstream and away from the king lead at the dizzy cap, rotor arm, plug leads, plugs, or ignition timing so that is where to look - see " Other Components" (later) for checking the usual suspects, inspect, clean, substitute and only replace if faulty.

o If No - change the king lead.

o If still No - then the problems are upstream from the king lead and towards the coil, amplifier, distributor innards or their local connections all the way back to the ignition switch.

Testing the Low Tension Side Voltage Feed

o Switch on the ignition and use a multimeter to verify there are 12 volts at coil positive.

o If No - find out why, by checking the circuit between coil positive and the ignition switch and beyond, all the way back to the battery if necessary, for corroded or loose/broken connections.

o If Yes - dont take it for granted, waggle local wiring and toggle the ignition switch a few time to ensure the voltage is reliable, even using a bright lamp to check the wiring can supply a load.

Test the coil independently

o Disconnect the wire from coil negative to the amplifier.

o Turn ignition on, and strike coil negative to earth with a flying lead to see how good is the king lead spark.

o If sparks are absent/poor/weak and +12 volts is still present at coil positive then the coil is prime suspect for inspection/replacement.

o If sparks are fat/healthy then coil must be OK, so look for amplifier/pickup coil problems.

Test the Amplifier and Distributor Pickup Coil Together.

o Remove Distributor Cap.

o Disconnect ECU trigger wire from the 6.8k ohm resistor to prevent spurious signals getting to the ECU.

o Disconnect amplifier wire from coil negative.

o Connect a 12v 21W bulb from the same amplifier wire to coil positive (12 volt supply).

o The 21W bulb acts as a substitute coil load.

o Turn ignition on and rotate distributor rotor arm back and forward against the vacuum/mechanical advance springs.

o As the toothed reluctor wheel triggers the pickup coil, the amplifier should flash the bulb.

o If bulb flashing is positive and consistent the amplifier and pickup coil are working correctly together.

o If lamp does not flash or is inconsistent/weak either the amplifier or pickup coil is faulty.

Check the pickup coil independently

o Remove the amplifier connections to the pick-up coil and measure the resistance of the distributor pickup coil for a steady value between 500 ohms to 1500 ohms on the ohm-meter. Flex the wires at the same time to test their integrity.

o Outside the above range, short or open circuit indicates a croaky pickup coil.

o By process of elimination, if the pickup coil is OK, one might conclude the amplifier is faulty but nothing is ever that simple with electronic components, so to be sure:

Test the Amplifier independently

o What follows is an elegant but slightly complex test process.

o Use a 1.5 volt pen-cell battery connected in series with a (say} 2,700 ohm resistor and two flying leads to simulate the pickup coil.

o With the coil and amplifier connected normally and the distributor pickup coil disconnected from the amplifier, connect one flying lead to one of the amplifier input connectors and touch the other flying lead intermittantly across the second amplifier input connector.

o This emulates a pulsed input thereby activating the amplifier in sympathy to generate sparks from the coil?

o Polarity of this simulation is non-critical as neither flying lead is connected to earth, only to the amplifier input connectors, and the pulsing voltage from the pen-cell via the 2700 ohm resistor acts similar to the pickup coil input without causing stress or damage to the amplifier.

o The above test can be performed with the 21 watt bulb as the coil substitute as previously described, except in that circumstance, the pick-up coil simulation will flash the bulb.

Alternatively (for even more elegance), going one step further:

o Construct a small test box complete with switch, 21 watt bulb/holder, pen-cell battery, 2700 ohm resistor, 12 volt pos/neg power connections (from a car battery), spade connectors to the amplifier, etc.

o Connect up the 12 volts power and the amplifier to the test box and flick the switch repeatedly to emulate the pulsed input from a pickup coil and see the 21 watt bulb flash in sympathy to show the amplifier is working correctly.

Other Components

o Another possible component failure will be the suppressing condenser breaking down under the back-EMF from the coil.

o Remove condenser from circuit to see if the problem disappears.

o If yes, replace the condenser.

o Almost finally! For all the previous components check the LT wiring is not corroded, broken, dodgy or otherwise failing.

o Because all the components upstream of the king lead now check out OK, if fat sparks emerge from the king lead but not at the spark plugs its time to review the downstream components to see if they are dragging down, or failing to conduct, the Hi-Tension energy.

o Rotor arm - inspect for carbon tracking, clean with WD40, smear with a trace of silicon grease to prevent moisture ingress.

o Distibutor cap - inside and outside - inspect for carbon tracking, clean with WD40, smear with a trace of silicon grease to prevent moisture ingress. Wipe completely clean and shiny, especially between the turrets.

o Plug Leads and Hi-tension connectors - inspect for breaks and contact damage, clean with WD40, smear with a trace of silicon grease to prevent moisture ingress. Wipe completely clean and shiny.

o Spark Plugs - Check for recommended type, clean and gap to correct spec, inspect for insulator damage externally and whiskering/crud between central contact and body. Clean externally to a shine.

o The above four items are "zero cost" actions. Many owners replace them all never knowing which of the components may have been faulty.

o Check by swapping is an easy process before buying replacements.

o Looking for spark tracking on a dark night generally reveals faulty hi-tension parts.

Hello.
I may have "labelled" it wrong as English is not my main language I used the white paste stuff that was supplied with the new amplifier module.
@ Ramon : I've studied your diagram in another thread an I have a look in the morning.
" Turn ignition on, and strike coil negative to earth with a flying lead to see how good is the king lead spark. " This means I should connect a wire to negative and striking it towards ie the earth connection at the coil?



As for the old amplifier module, almost no paste where present, so I was unsure if I used too much at the new one?!

Hi again.
I dismantled the new amplifier unit, and removed some of the paste which was applied aplenty, but not all of it.
I then checked the coil the following way : The main ignition lead from coil to distributor disconnected at the dizzy, and put on the inner wing close to a metal wrench key. Turned on ignition and cranked the engine - no spark. I then removed the black/white wire from the coil as described above, connected a wire to the earth strap near the coil and stroked the negative terminal where I removed the black/white wire, coming from the amplifier. It made a small blue spark at the connector, so current is present, but the lead produced no spark.
I guess this means the coil is done?!

I guess this means the coil is done

I does seem that way Lasse. Just to be sure, your little LT spark certainly implies the low tension side of the coil is working, but you did have a spark plug on the king lead laying on the engine somewhere, as mentioned at the beginning of the test procedure, didn't you?

o Remove the king lead from the distributor, connect it to a good spark plug and lay the plug on the engine somewhere.

There is of course one other possibility for it not being the coil, and that is that the king lead may be faulty, so to be sure, try one of the plug leads in its stead.

Good luck.

Hi Ramon.
No, in the tests of the main lead I didn't have a spark plug connected. In the beginning it sparked anyways though. I've tested with another lead, no difference.
A friend of mine dropped by with a voltmeter, and we measured the coil. Directly at earth and positive 11,85V, when tested at coil positive and negative, zero volts.
The ignition coil I have is a small Tefca unit, but I haven't been able to find a similar on the net. I reckon this will do as replacement :

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

Lasse, That seems to confirm the coil is duff then. I think the reason for using a spark plug as standard practice, is to ensure the high tension voltage is jumping the correct gap.

If the gap is too small then the coil is not working hard enough and may still be faulty, and if the spark is being asked to jump (say) a centimetre then the voltage builds up too high and could cause damage and tracking inside the dizzy cap - for example.

The high tension voltage will always seek the path of least resistance to earth - ie the smallest gap.

It just bullskit science really and none of it really matters - I guess - as you seem to have found the fault.

The ebay unit certainly seems to be specified for the RV8 generic systems.

Hello.
Bad news. I recieved the new coil and installed it, tried to start the engine - no effect! It's just turned by the starter, but no ignition. I tried twice with no effort. Then my cousin tried, and it fired up immediately! We let it run in idle a few minutes, then turned it off and tried to start it up again. Then it wouldn't start. After a series of attempts it would fire up, but being shut down it would take numerous tries before it ignites.
I reckon it's a periodic error in the electrics ( british cars and electrics ). Maybe a relay that's "hanging".
Could it be the ignition key mechanics that are worn down?
The anti-theft ignition cut-off?
Or simply a bad relay that can disconnect the ignition?
Is there any chance a read-out of the diagnostics will reveal the error? No warning lights are showing however.

I hope some of you have a clue or a hint for a guy who's pretty tired of spending money on parts to no avail..

You can fit a test lamp between coil +ve and the bodywork. The lamp should come on with the ignition.

Chris.

I had a TR7, sometimes the engine wouldn't fire. Eventually found the ignition switch was faulty and not always powering the coil. If I remember correctly the ignition light didn't come on either.
HTH Stu

You'd need to check the vehicle wiring diagram to see if there is a relay in the path - but I doubt it. However, it is easy enough to check there are volts at the coil + when the ignition is on, but it won't start. Probe the coil + with the feed still connected so you're measuring the volts under load.

You say you've replaced the amp. Are you sure that one is good? It's by far and away the most likely cause of an intermittent fault. I've known new aftermarket ones to be faulty.

Other thing I'd try is to disconnect the rev counter feed from the coil negative. An intermittent short etc there could cause the symptoms.

But all this assumes it is an ignition fault which is the problem.

Hi all.
@ Dave : I have a high-comp 3,9 engine in the garage, I'll try switching the new amplifier with that from thhis engine then.
Funny you should say " if it's an ignition problem".
When turning the engine, it revs rather freely, as if lack of compression. A workmate of mine occured a problem today with his Peugeot 206. It died on him after he reversed it out of the driveway, and it took him 5 minutes to start again. He said it was due to low oil-level and the hydraulic lifters not pumping up, hence not opening the valves.
When I bought the RR, it ticked from the lifters, due to wear (185.000 km's approx.). It ran 10w40 semi synth oil. I changed to Castrol 25w50 as I read in my Haynes it should use this viscousity oil.
It took away some of the noise, except it was worse when cold and quieter warm. At roughly the same time the ignition problems began, it would leave the oil light on for a matter of 10-20 seconds after the engine fired up.
Could it be the lifters not pumping up?

Update : It turned out to be a defect ignition switch. A mate who's a mechanic advised me, that if the lamps for oil and battery went off as soon as I turned the ignition key to start the engine, then I should try connecting the +15 on the coil directly to the battery. If it would fire up this way, then the ignition switch was defect.
I tried, and it fires, so now I've ordered a new igition switch and steering lock (apparently you have to buy the whole kit) at Paddocks, and awaits its arrival .
Thanks a lot for your advice, I learned a bit about the electrics that might come in handy later .

Lasse Kristensen wrote:Update : It turned out to be a defect ignition switch. A mate who's a mechanic advised me, that if the lamps for oil and battery went off as soon as I turned the ignition key to start the engine, then I should try connecting the +15 on the coil directly to the battery. If it would fire up this way, then the ignition switch was defect.
I tried, and it fires, so now I've ordered a new igition switch and steering lock (apparently you have to buy the whole kit) at Paddocks, and awaits its arrival .
Thanks a lot for your advice, I learned a bit about the electrics that might come in handy later .

Do you have a DVM? Quite reasonable ones can be bought for a few pounds these days.

You need a bit of laterlal thinking to test the feed to a coil as the coil probably won't draw much current if any with the engine stopped. So substituting a bulb - say a headlamp one which takes about 5 amps - would have shown up a fault in the ignition switch.

The main thing to remember is just checking the voltage at any point tells you little unless the circuit is running at or near its normal load, as the DVM itself draws no current.