[thejagman]

Hi guys, I could do with a fresh pair of eyes as this one has got me stumped.

RR is a 1993 LSE with 4.2 engine petrol/LPG. I have owned this for about 5 years now and changed/renewed so many things during this time during its rolling restoration. Normally runs great.
The symptoms:

Car starts fine every day from cold, sounds beautiful and quickly settles down to a nice tickover. Off down the road, no issues, no spluttering, no stalling at stops
or junctions --until after about 5 to 10 minutes when the engine has warmed up properly and the temperature guage is in the middle (as it always has been), the engine will just die. It is instant just like I have turned the key off.
I slip it into neutral (autobox) whilst coasting to the side of the road and try restarting. The engine cranks and spins over but not a hint of a restart. Tried it in Park and Neutral in case there was any problem with either but to no avail, it will crank and crank but not start. The engine is not overheated, it never has been, when I refer to it as hot it is normal operating temperature.
The same will happen if I start it from cold and just leave it idling on the driveway, once it warms up it will just stop. Cranking it over and it will not go.

I leave it for an hour or two, turn the key and it fires up as if there has not been a problem, just like it does every morning.

The reason it will not fire, is that there is no spark ( maybe other things, but that is the most obvious and first that should be adressed). Something is kicking in when it gets to a certain temperature and knocking out the spark and that situation remains until it cools.

I dont believe it is fuel related as the same thing happens whether it is on petrol or gas (Prinz VSI). If one fails or runs out it automatically switches to the other. I also completely disconnected the gas and ran it for a week just so I could eliminate that side. Plugged in Roverguage, no fault codes shown, switched the fuel pump on and off manually and you can hear it running - but these points are all irrelevant (or are they?) if there is no spark.
I have just fitted a new ignition amplifier module relocation kit (now mounted by the coil on the wing) as that is a known problem with the originals on the side of the distributor getting too hot and failing. That didn't solve anything. I have changed the coil checked and double checked all the connections and terminals and they all seem good. There is 12v to the coil with the ignition on but nothing coming out of the king lead when cranking. I have an in-line tester that shows any current going through it.

I am missing something very simple here I am sure, but it is driving me nuts - any suggestions would be very much appreciated.

 

[xalt]

Check your coolant temp sensor, that's the third most likely behind the coil and the amplifier, but you'd still get spark if it were the case. Someone else had issues with a loose O2 sensor wire grounding out and causing hot stall as well.


Maybe your replacement ignition amplifier or coil is faulty...

 

[thejagman]

Thanks for the suggestions, as you say, the coolant temp sensor if breaking down would send the wrong signals to the ecu but not cut out the spark. The symptoms are the same before and after the ignition amplifier and coil change which in my mind sort of rules them out.
The grounding of the O2 sensor is a consideration, l'll double check all the wires - but again it cuts out when hot and works when cold. If the insulation on a wire was affected by heat and had melted to cause a short it would not 'fix' itself when it cools down time and time again.

 

[pl626]

Thanks for the suggestions, as you say, the coolant temp sensor if breaking down would send the wrong signals to the ecu but not cut out the spark. The symptoms are the same before and after the ignition amplifier and coil change which in my mind sort of rules them out.
The grounding of the O2 sensor is a consideration, l'll double check all the wires - but again it cuts out when hot and works when cold. If the insulation on a wire was affected by heat and had melted to cause a short it would not 'fix' itself when it cools down time and time again.

Will it fire on ether after it quits? Could be you have debris in your fuel tank that clogs the pump or filter after running a while.


Sent from my iPhone using Tapatalk

 

[thejagman]

It quits on either and won't restart or fire on either, which is why I went down the electrical route and discovered that there is no spark.

 

[95classiclwb]

distributor pick up plate perhaps,(the trigger inside the dizzy). it is a coil thus if it shorts due to high temps it grounds and fails.

 

[Tom109]

I have experienced similar with a failing ignition amplifier module (IAM). My stalls at speed were instant as you describe, and typically resulted in a restart within 3-30 minutes of pulling over. That was the early stage of a failing IAM, eventually re-start time increased, and shortly after it would not start at all (failed). Swapping out to a new IAM eliminated the stalling. My IAM is now relocated next to the coil, behind the LH headlight.

It is also worth noting that on my 1995 the black/white wire from the coil triggers the injector circuit via the ECU. Make sure this wire is intact and the connector solidly attached. A short here would cut the injectors and simulate a bad IAM.

 

[JS5D]

I second the Ignition Amp Mod dying when hot. For exactly this reason SimonBBC sells a remote wire solution where the amp is mounted at a 'cooler' location on a heat sink. Not expensive and you get a new amps so rules that out.

 

[thejagman]

Thanks for the suggestions guys, i have as mentioned relocated the ignition amplifier module to the wing as this was my initial thoughts. It is the one sold by SimonBBC with the more expensive IAM. Today I stopped out the complete distributor I had, as a known working spare as the air gap/pickup might have been out and insufficient when hot. No change!!!
So in total that's 3 IAM's that have been tried, both attached to the distributor and in the new location on the wing plus two coils.
When it happens, there is no spark at all, so I have pursued the electrical fault route right from the start. Whilst I know the fuel pump is working ok and the fact that it is dual fuel with LPG gas as well I keep discounting the fuel side as it happens on either. Is there anything in the ecu operation that IF and its a big IF at the moment, it detected a fuel issue it would cut the spark?

 

[thejagman]

Just as a further add on to my last post regarding fuel, the Prinz VSI LPG system is completely independent from the petrol, it has its own injectors for each cylinder, own ecu, but it is linked to turn the petrol pump off when running on gas and on again when you switch back to petrol. May be irrelevant but I thought I would put it into the thought process.

 

[JS5D]

Thanks for the suggestions guys, i have as mentioned relocated the ignition amplifier module to the wing as this was my initial thoughts. It is the one sold by SimonBBC with the more expensive IAM. Today I stopped out the complete distributor I had, as a known working spare as the air gap/pickup might have been out and insufficient when hot. No change!!!
So in total that's 3 IAM's that have been tried, both attached to the distributor and in the new location on the wing plus two coils.
When it happens, there is no spark at all, so I have pursued the electrical fault route right from the start. Whilst I know the fuel pump is working ok and the fact that it is dual fuel with LPG gas as well I keep discounting the fuel side as it happens on either. Is there anything in the ecu operation that IF and its a big IF at the moment, it detected a fuel issue it would cut the spark?

Could it be the coil? Have you tried changing that?

Since it does not misfire but dies entirely and you have no spark (on all plugs I presume) it has to be the bit that makes the spark in the first place.

Most people with engine running issues are not so lucky to have it narrowed down to this point.

 

[canadaboy25]

Could it be the coil? Have you tried changing that?

I truly hope you're joking.....

So in total that's 3 IAM's that have been tried, both attached to the distributor and in the new location on the wing plus two coils.

OP - I would use a test light and make sure that you are getting a ground pulse from the distributor on the negative side of the coil. I know you said you changed it but it would be a good thing to check if you haven't already. Also make sure your engine block has a strong clean connection to the frame and to the battery.

 

[RRLondon]

In respect of the last point above, it seems to have ground to block as it cranks ok. But, try putting a jump lead from coil mounting to engine block to make sure that end of the circuit is working.

Have you changed the king lead? It's obviously common to all sparks and any impairments will kill all output from coil. I've worked on these for years and had a king lead failing recently, I couldn't account for what was happening and it took a couple of days to find the cause. It really defied logic but it's the only component I changed to get it going correctly, everything else checked out and I don't like randomly swapping stuff as I like to know the real cause of failure as it ultimately helps me in future.

Since then I've held a sparking the tool kit, although I doubt I'll get that again.

 

[RRLondon]

That should have read " spare king lead" above, but my predictive text got me.

Also consider the rotor arm and distributor cap.

Unsure where you are testing for spark, is it at the dis end of the king lead?

 

[Syam]

Hi I'm new here.. I think it might be the crankshaft sensor

 

[RangeGuy]

+1 on the crankshaft sensor- happened in my Disco 2. Mechanic who fixed it said it was a common problem.

 

[95classiclwb]

Hi I'm new here.. I think it might be the crankshaft sensor

its a classic, no such thing as ckp on factory ignition.

 

[thejagman]

I was testing the King lead at both ends with the inline tester, but have now also changed the lead, put on a brand new cap and rotor, despite already swopping the whole distributor. I used a jump lead from the coil mounting point to the engine block to guarantee a good earth, also cleaned the earths from the body to the battery and engine to body.
Unfortunately problem still exists. I have removed the rubber boot from the ecu and all connections appear clean and secure. I have ordered a new Coolant Temp Sensor which should be here in day or two and report back on any change.
The Range Rover Classic does not have a crankshaft sensor