97 D1 3.9 V8 electrical issues, engine stalls when hot. pulling my hair out!

[Steve269]

Sorry for such a long post, I need help or fresh ideas.

Around a month and a half ago I purchased a 97 D1 V8 on duel fuel to replace the 200tdi Defender that I regrettably had to sell last year.
the car itself is in awesome condition for its age and has under 200k km on the clock so its fairly low k's. The PO has spent a small fortune on maintenance with his trusted mechanic. I was at the time confident that this was a good buy and very unlikely to be someone else's problem.
All was great for the first 2 weeks, then one night without warning the engine cut out, we pulled over and figured that the gas tank was empty, switched to petrol and attempted to restart the engine but it didnt want to fire so we had it towed home. The next morning it fired up first go, it also started on gas so Im thinking that the gas sender is telling lies.
Its done this a few more times since while I try to diagnose the fault. It happens when the engine reaches a certain temp, it looses spark and will remain this way until the component causing the issue cools down and allows the engine to restart, well this is my theory on the problem after much research thanks to google and various forums in general.
The problem is present on both fuels so Ive ruled out any fuel pump or filter issues for the moment.
The PO had a "Powerspark" distributor and coil fitted aprox 2 1/2 years ago.
I have gone through the following in an attempt to resolve the issue.

Tested ignition system as per LR Disco WS manual at least 3 or 4 times, both while engine is cold and at fault and cant find any reasons to suspect ignition system components at least as far as WS manual is concerned.

Replaced
Ignition Amplifier Module as it seamed the logical thing to have gone wrong.
Coil HT lead as I wasnt happy with the resistance of the old lead.
Swapped coil for known good unit, however made little to no difference.

Cleaned all electrical connections, plugs, earths, etc in engine bay, fuses and relays as well as ecu plugs etc in front foot wells. Also tightened any female spade connectors I could.

Tested and found
Distributor pick up, Resistance tested when fault present at 3250 ohms, within spec according to my manuals. I did find that the pick up coil had separated from the magnet so I cleaned the area and glued it back in place as a temporary measure. I also found that there was no air gap so I reset the air gap to .25 mm within the specification set out in the manual. Im suspect of this unit however Im not fully convinced that replacing it will solve the issue.
Engine security ecu, bypassed the immobilizer function by bridging the two orange/black trace wires into terminals 10 and 11 of the output plug, this made no difference. I did remove the unit and open it up to inspect the PCB as the green case has a crack in it, found nothing untoward other then a possible small scorch mark, all soldered joints are intact. I found out the hard way after removing the center dash that this car hasnt got the frail spider unit.
Ignition switch, tests and operates ok, nothing obvious jumped out at me at least.
ECU fuel temp sensor, I cant recall the results of resistance tests however Im satisfied its working ok.
ECU ECT sensor, Tested with jacket water cold and hot while in fault, resistance when hot came in around 200 ohms, according to what Ive read this puts the jacket water temp in the region of 100 deg C. I also tested the cluster gauge sender as the cluster gauge was reading normal operating temp when fault presents itself. I trust neither of these sensors and intend on replacing both. not sure if they are related to the problem though.
TPS, tested resistance through its range and from memory resistance decreases as throttle is opened, I was using a digital meter so couldnt tell if it has any sticky spots.
Vacuum Advance unit was tested ok.
Stepper motor/Idle bleed valve, appears to be working fine, the PO told me it was replaced in the last 6-12 months, not sure what breed the replacement his mechanic installed is though.
Tested some of the electrical leads associated with the above components where possible, much of the wiring has been sheaved with that black corrugated conduit and is semi untraceable without a suitable assistant.
I have as yet not tested any relays but will do so when I get the time.
I found the Airflow sensor to be covered in red dirt, I removed it, took the ends off and cleaned with electrical cleaner and tested it for earth faults but it seams to be ok.
The only other component Im unsure of is the charcoal canister purge valve, I have been unable to inspect it, but im not sure if it could be in any way related to my problem.


Im reaching the end of what I can do to solve this issue, I dont want to go down the path of replacing expensive components only to find that the problem is still present. I have already done this to a small degree when I replaced the Ignition Amplifier. Im also reluctant to send it to a workshop so they can do the same tests again and find nothing conclusive other than speculating what might be causing the issue.
I dont want to let this thing beat me, I need some second opinions or fresh ideas. Has anyone had the same of similar issues and what was the fix?

Thanks in advance for any useful ideas etc.

Steve

[Rick1970]

Pick up sounds sus, from memory resistance should be more like 2000. Search bosch bim024 ignition mod, worth doing

[Steve269]

It appears I’ve lost the zero on the end of that figure. It’s ment to read 3250 ohms.

[Rick1970]

That sounds better.
As it seems heat related, maybe try preheating dissy coil etc with a heat gun or hair dryer, then try a cold start. Sounds ignition related.

[bee utey]

My thought is that the Powerspark is an aftermarket copy of the original distributor, probably made in China. Therefore you would be best off replacing the ignition module with a Bosch BIM024 one. It requires some wiring and a bit of fab for a suitable heat sink. Be aware that there are cheap Chinese copies of the BIM024 too, get a genuine Bosch one. They're not that dear.

Lucas ignition amplifier replacement by Bosch 024 (https://www.aulro.com/afvb/technical-chatter/96950-lucas-ignition-amplifier-replacement-bosch-024-a.html)

[DAMINK]

Had the same thing happen MANY TIMES! Been stranded out bush more times than i care to remember. Had to leave my car several times.
I like yourself have chased my tail so many times trying to fix it.

After doing the bee utey module change no difference. Actually thats not true. It ran a lot better when it ran but the shutting down issue was not fixed by doing said change.
I changed the wiring from the dizzy to coil thinking that could be it. No difference. Moved coil and module to firewall no difference.

Long story short i found that when i moved the loom that the maf connected to it fixed the problem. Approx where the loom crosses behind the engine.
So now when i have the issue i grab the loom and give it a wiggle..... For lack of a better term.

Now my car has been running fine for months without doing it. Prior to that it done it sporadically for years.

I assume there is a faulty wire there somewhere and when my wiggling no longer works i will likely have a dip at replacing it.

Quite possibly not the same problem but just putting it out there incase it is.

[PhilipA]

Dredging back into memory there is a wire that tells the 14CUX that the engine is operating and the revs. It goes from the coil to the ECU and is attached to the loom to the MAF. It is what tells the injection to cut off over 1500RPM on closed throttle as well as other stuff.
I bad connection that heats up over time would cause the engine to cut out.
I don't know whether there is some connection to the gas but something to look at.
have a look at the connectors.
Also you don't appear to have done a 14CUX diagnostic.
Regards Philip A

[Steve269]

Thanks for all the suggestions and info so far.
I’ve had a go at the old wriggle the wires trick but I’m not convinced I’ve got the right part of the harness yet.
Over the weekend I plan on testing all associated relays and wiring circuits etc.
After some light reading on the subject of 14CUX I will do some basic diagnosis of the signal voltage to tps, ect, etc and associated circuits for faults, this isn’t beyond me with the tools I have. I don’t have access to any diagnostic scan equipment so once I’m satisfied I’ve tested all I can test I’ll find a friendly local mechanic and get their computer talking to it.
I was hoping I could put a jumper lead between two terminals of the diagnostic plug and get the codes to flash on the dash similar to how my VR Commodore did.
Once the problem is fixed I plan on relocating the ignition amp remote from the distributor, I think it’s crazy to have a sensitive electronic component in a hot environment like that.

I’ve only recently just reversed the bodge job one of the previous owners did to the ignition system of my Series 3 Lightweight, that was all mechanical and it’s a weekend play thing. This Disco fiasco is really testing my memory of what I’ve learned about electronically operated control systems etc and I really need it back on the road for weekday transport duties.

[Old Farang]

I don’t have access to any diagnostic scan equipment so once I’m satisfied I’ve tested all I can test I’ll find a friendly local mechanic and get their computer talking to it.
You will not get any joy there. The ECU is "dumb" and does not talk to anything. There are some after market basic test devices, but they will not tell you what the problem is. I had a similar problem with my 97 V8, and as posted, it is more than likely a wire or connector problem, rather than any sensor.

[PhilipA]

All USA 3.9 RRCs had a diagnostic screen under the seat.

I bought one cheap from a US wrecker and wired it in to my ECU plug.

The connector that is under the seat is for a dealer diagnostic tool and cannot be used.

I have to agree with the dumb bit as it would read active faults but not remember them.
I used to test it every now and then by disconnecting the MAF and it would show the fault, but it never ever came up with a fault any other time, although I don't think I had any.

The reader is far more useful when o2 sensors are fitted as the program for o2 sensors has far greater level of inputs. I fitted O2 sensors to mine but I checked the functionality by also fitting a titania sensor and reading the o2 live with a mutimeter

I would also redo all the connections to the gas and replace the relays with new ones, as they are not expensive.
Regards Philip A

[Steve269]

I’ve function tested all the important relays and harness. Found nothing of any interest.
Tested to function of the tps with an analogue ohm meter for the fun of it. It tests as I’d expect. However I did tug on the harness a little when removing it, it started ok but then started coughing and spluttering, couldn’t decide where it wanted to idle then died as I moved the harness. It’s stone cold and won’t start now so I’ll be tested the harness next.

[Old Farang]

The reader is far more useful when o2 sensors are fitted
Mine has factory fitted O2 sensors, it also has one of those weird, if I recall correctly 3 holes, sockets. You can read the ABS faults, and the alarm system. but still not the ECU. All of the sensor inputs are voltages, so can be read with a DVM. The after market "ECU Mate" will show all the inputs as the algorithm just converts them to a graphical display. Maybe some of the others will also do that also, I do not know.

[PhilipA]

Clean the plug on the MAF, then get a pair of long nose pliers and twist the male contacts GENTLY about 10-15 degrees. This ensures a good contact.
Regards Philip A

[LRJim]

Just having a guess because it hasnt been mentioned. Have you checked the inertia switch? I doubt the LPG will be linked to it though.
Cheers Jim

[Steve269]

I’ve had MAF out and thoroughly cleaned it and it’s plug. I’ve tightened the female terminals, never heard of giving the male pins a little twist, I’ll consider that before I rip out the harness.
I’ve checked the inertia switch multiple times.

[LRJim]

I’ve had MAF out and thoroughly cleaned it and it’s plug. I’ve tightened the female terminals, never heard of giving the male pins a little twist, I’ll consider that before I rip out the harness.
I’ve checked the inertia switch multiple times.Just thought id ask just incase you never know. Sounds like the same issues I was having after I washed the engine bay. Ran around all the same circles you are, I still don't know 100% sure what fixed it. I put it down to either the original amplifier which for i know could still be fine or some dodgy connectors going to the coil. I recently found out one is a resistor not just a dodgy joiner maybe I fried that. In the middle of those joiners is the resistor, I just put in a joiner. I havnt replaced it but I changed to the Bosch amp anyway do I doubt it's needed. If you have the same looking plugs maybe try a joiner instead you never know it could be anything.
Cheers Jim https://uploads.tapatalk-cdn.com/20180929/d877ac5e1cbed2d6acd22f87b4d1f79d.jpg

[DAMINK]

That resistor is important.


There is considerable variation according to application so please check for the correct version for your vehicle. If the vehicle is modified then the supplier of the modified ECU software should have specified the correct tune resistor to use.


Wire Colour

Resistance (Ohms)
Catalyst
Operation
Common Application


Red

180

No
Australian 3.9


Green

470

No
Europe & UK 3.9 (or 3.5 Disco)


Yellow

910

No
Gulf States 3.9, or Europe & UK 4.2


Blue

1800

Yes
Gulf States 3.9, or Europe & UK 4.2


White

3900

Yes
Europe & UK 3.9 (or 3.5 Disco)




Source Lucas 14CUX Fuel Injection System – Installation and Diagnostic Notes. - ACT Performance Products - your source for after market TVR upgrades, components and performance accessories. (http://www.actproducts.co.uk/2011/lucas-14cux-fuel-injection-system-%E2%80%93-installation-and-diagnostic-notes/)

[PhilipA]

That resistor is important.
AFAIK from looking ,you are talking about the tune resistor which is attached to the ECU under the seat not in the engine bay.
I have an OZ one if anyone wants it, as I changed to a UK one when I fitted the O2 sensors. I found it in a toolbox a couple of days ago.

Regards Philip A

[DAMINK]

AFAIK from looking ,you are talking about the tune resistor which is attached to the ECU under the seat not in the engine bay.
I have an OZ one if anyone wants it, as I changed to a UK one when I fitted the O2 sensors. I found it in a toolbox a couple of days ago.

Regards Philip A



You could well be correct Philip.

I do recall this exact resistor he is showing. Its near the airbox area.

[bee utey]

There is a resistor in the signal line between the coil negative post and the ECU and it is indeed near the coil. I'm not sure how important it is but then again I've never seen any good reason to remove it.

[PhilipA]

I do recall this exact resistor he is showing. Its near the airbox area.

I think the one in the engine bay is a diode not a resistor.
I can vaguely recall wondering why they had a diode there as the signal went to the ECU not the other way.

Regards Philip A

[DAMINK]

I think the one in the engine bay is a diode not a resistor.
I can vaguely recall wondering why they had a diode there as the signal went to the ECU not the other way.

Regards Philip A

Excuse my ignorance but being a diode there what purpose would it actually have? Some sort of protection to prevent current going to where?

Just reading stuff trying to learn.


* Could this be a protection for reverse feed into the ECU? If so i imagine its quite important to keep it there?

[LRJim]

Like I said it was one of the last things i done then it ran again. They were covered in crap filled with water. I'll try and get some new ones and replace them especially if it could be protecting the ecu. Only recently I found out that they are a resistor. They have a grease In them which I reckon over 20 years is no longer protecting the insides. From memory it's a resistor not a diode, I still have it here I'll check what it says.
Cheers Jim

[DAMINK]

Like I said it was one of the last things i done then it ran again. They were covered in crap filled with water. I'll try and get some new ones and replace them especially if it could be protecting the ecu. Only recently I found out that they are a resistor. They have a grease In them which I reckon over 20 years is no longer protecting the insides. From memory it's a resistor not a diode, I still have it here I'll check what it says.
Cheers Jim

I have often thought of doing just what you did Jim. But got confused to its purpose so left it be.
Definitely have had that in my sights as a potential issue. And similar to yourself mine was crusty and filled with crap also.

[LRJim]

Withought going outside and looking for it. I googled it and I'm pretty sure it's this "lucas 953066".
It's definitely a resistor that being short protects the ecu.
Some stage today I'm gonna clean it up and put it back in and see what happens.
Cheers Jim

[DAMINK]

Withought going outside and looking for it. I googled it and I'm pretty sure it's this "lucas 953066".
It's definitely a resistor that being short protects the ecu.
Some stage today I'm gonna clean it up and put it back in and see what happens.
Cheers Jim

Yea mine is the same with an RD i think infront of the numbers. Hard to tell with my eyes.

[Old Farang]

That resistor is important.



Source Lucas 14CUX Fuel Injection System – Installation and Diagnostic Notes. - ACT Performance Products - your source for after market TVR upgrades, components and performance accessories. (http://www.actproducts.co.uk/2011/lucas-14cux-fuel-injection-system-%E2%80%93-installation-and-diagnostic-notes/)
This is the tune resistor, nothing to do with an inline resistor near the coil. And on mine the tune resistor is buried in the harness under the dash.

[Old Farang]

Withought going outside and looking for it. I googled it and I'm pretty sure it's this "lucas 953066".
It's definitely a resistor that being short protects the ecu.
Some stage today I'm gonna clean it up and put it back in and see what happens.
Cheers Jim
If it is inline with a white wire it is shown on mine as a "suppressor", and simply shunts to ground. There are a couple of variations depending on year of manufacture, accessories and manual or auto trans.

[LRJim]

If it is inline with a white wire it is shown on mine as a "suppressor", and simply shunts to ground. There are a couple of variations depending on year of manufacture, accessories and manual or auto trans.Well I've put them back In after giving them a good clean. No dramas it runs fine if not a little more stable. I read somwere that 1 is the wire that sends the RPM to the ecu, I don't know about the other one. I'm guessing the resistor or suppressor helps stabilize the signal to the ecu. I'll have a closer look and see I the other goes to ground or somewhere else.
You can't tell in the pic but one has 2 wires in and 1 going out might give a better idea what their for.
Cheers Jim

[Steve269]

I gave the car a kick in the guts this morning and it started, so I warmed it through and started more probing of sensors while running. Nothing untoward was noticed until I turned on the A/C, the engine began to stall so I turned it off and the engine recovered. I switched the A/C on again ready to give the engine some throttle but it stalled and wouldn’t restart.
I’ve looked at the wireing schematics and the only thing I can see common to the A/C circuit and the circuits that include TPS, ECT, EFT, MAF, Fuel Injectors etc is the “Engine/ Ignition Load Relay. Is it possible this relay is at fault? Has anyone come across any similar occurrence? Or am I missing something?

[LRJim]

I gave the car a kick in the guts this morning and it started, so I warmed it through and started more probing of sensors while running. Nothing untoward was noticed until I turned on the A/C, the engine began to stall so I turned it off and the engine recovered. I switched the A/C on again ready to give the engine some throttle but it stalled and wouldn’t restart.
I’ve looked at the wireing schematics and the only thing I can see common to the A/C circuit and the circuits that include TPS, ECT, EFT, MAF, Fuel Injectors etc is the “Engine/ Ignition Load Relay. Is it possible this relay is at fault? Has anyone come across any similar occurrence? Or am I missing something?I read that you tested the TPS already but did you adjust it? I like most have slotted the holes. Or adjust your MAF? What timing are you running? And do you have the 14cux injection booklet? Maybe your base idle needs adjusting also. All these things randomly need adjusting now and then lol
Cheers Jim

[PhilipA]

Before changing the base idle, clean out the throttle body and the throttle blade. oily gunk can build up on it from the crankcase ventilation.
After you have done that look at the base idle which should be 550-600RPM. You adjust by blocking off both sides of the stepper, and turning the screw on the throttle body , out for more.
The stepper should then compensate for the AC.
Maybe replace the load relay also, although never really heard of this as a problem.
the stuff above will not affect running other than idle.
Regards Philip A

[LRJim]

Before changing the base idle, clean out the throttle body and the throttle blade. oily gunk can build up on it from the crankcase ventilation.
After you have done that look at the base idle which should be 550-600RPM. You adjust by blocking off both sides of the stepper, and turning the screw on the throttle body , out for more.
The stepper should then compensate for the AC.
Maybe replace the load relay also, although never really heard of this as a problem.
the stuff above will not affect running other than idle.
Regards Philip AYou would know better than I with these, but it seems that it's warming up fine then dying and won't restart till everything's filled down. Dosnt it sound like MAF adjusting symptoms? Otherwise I'd say amp or coil overheating but he's changed them.
Cheers Jim

[bee utey]

I gave the car a kick in the guts this morning and it started, so I warmed it through and started more probing of sensors while running. Nothing untoward was noticed until I turned on the A/C, the engine began to stall so I turned it off and the engine recovered. I switched the A/C on again ready to give the engine some throttle but it stalled and wouldn’t restart.
I’ve looked at the wireing schematics and the only thing I can see common to the A/C circuit and the circuits that include TPS, ECT, EFT, MAF, Fuel Injectors etc is the “Engine/ Ignition Load Relay. Is it possible this relay is at fault? Has anyone come across any similar occurrence? Or am I missing something?

I would replace the relay, also look for wiring faults due to a LPG EFI cutoff relay either present or removed. I had a car come in a month ago with a very similar problem where a LPG cut to the injector feed was rejoined with a non waterproof connector, and that was corroded.

[PhilipA]

but it seems that it's warming up fine then dying and won't restart till everything's filled down. Dosnt it sound like MAF adjusting symptoms? Otherwise I'd say amp or coil overheating but he's changed them.


Well yes but I was just referring to it stalling with aircon on and it only takes a few minutes to clean the throttle body etc.

His main problem certainly sounds like something to do with ignition.

The MAF, I don't know. the motor will run with the MAF adjusted over a wide range. It's just that the CO will be high if the MAF has too much initial voltage . In fact you adjust the MAF to 1volt when you fit o2 sensors. I don't know if he has checked the MAF by putting a multimeter across the signal and earth and seeing if the value rises with the engine revs.
It could be anything even the ignition switch having a bad contact which heats up or the power relay.
Another more common problem is the bunch of in line resistors just near the battery. (whoops RRC talk there . I don't know if later D1 has them)
Regards Philip A
Maybe also check that the injectors are getting power when the car stops. Each bank fires all at once so a short or bad connection in the loom could stop it.

[Steve269]

IÂ’ve made a little progress, found the main engine Relay had cooked itself, checked harness etc no obvious reason why it had other than old age. Replaced that not expecting any miracles.
Continued testing all engine sensor circuits and attempted to trace the gas system circuit but that needs more time and thought.

IÂ’ve found when doing a continuity test of the TPS circuit that two of the wires are arse about. According to my Hains manual the red/black wire from ecu goes to blue on tps and yellow from ecu goes to green on tps. However IÂ’ve found they are crossed at the tps end of the harness. Will this confuse the ecu or is it that basic itÂ’s not going to bother it?

IÂ’ve also checked if power to injectiors while running on gas, there is power to the A bank but I didnÂ’t have enough time to see if they were firing or not before the engine cut out again. MAF also has power to it while on Gas.

[LRJim]

This is the 14cux manual it's for RRCbut it's the same system. Have you got the RAVE Manuel or just the haines Manuel?

https://o.b5z.net/i/u/6064257/f/14cux_fuel_injection.pdf

[bee utey]

You need to check that the TPS produces a varying voltage with throttle position on the plain red wire in the engine loom. The other wire should be a steady +5V from the ECU.

[Steve269]

Thanks for the replies.

I’ve got the hard copy Hains manual and the 14CUX on PDF set up on my phones book thingo app.

I’ll check those voltages later when I get it running again.

[Steve269]

Since my last comment I had to change my focus to getting my EH Holden Special ready to drive down to country Victoria for a friends wedding.
In a last ditched effort to find the problem I ended up pulling the dizy apart in situ to test and asses individual components. I found that the ignition pick up was in fact out of spec resistance wise and the friction springs in the base plate were broken as well as some average wires I missed the first time.
I found a used genuine distributor at a wreckers interstate and it’s solved the problem and it came with the remote mounted amplifier set up as well.
My other options were limited to replacement britpart dizy, get another powerspark dizy, some other unknown brand pick up or a scorcher dizy. The Scorcher option is still one I’m open to for the future.
I’ve found a few other parts that will need attention in the future.
The one good thing that can out of this saga is the fact that I got to enjoy a bit more use of my EH Holden and Series 3 Lightweight.