Did a search but didn't find much similar to my symptoms, so I'm looking for advice

Was driving at freeway speeds after about a 30 mile trip, a slight miss developed and the tach needle was jumping with each miss. As the miss became more severe, the tach would drop to zero RPMs then shoot back up again.

After 10-15 seconds of the engine miss becoming progressively worse, the engine stalled and I eased onto the next exit and coasted to the light.

At the light, the car started up and ran normal for a few miles, then exhibited the same stall/wild tach behavior as it had on the freeway. It stalled another half dozen times, running less time on each restart. Pulling into the garage took several restarts, and each time it'd die, it'd make this bleating sort of noise for a couple seconds just before it died.

The car has 62K miles on it and had the original fuel pump, so I put a new fuel pump in it, new filter and new barricade hoses (trying to cut the petrol smell in my trunk down). I blew on the discharge end of the old fuel filter to backwash it into a plastic cup, and the gas was a little coffee colored but no chunks- about what you'd expect. A bench test of the pump (dry) and it seemed to run ok.

After replacing the pump/filter/hoses, I drove it around the neighborhood until it came up to temperature, Once warmed up, the car stalled with the same symptoms: erratic tachometer, engine missing, bleating noise then the engine stops, but can be immediately restarted, but the stall cycle starts over again running progressively sorter and shorter each time - so it wasn't the fuel pump or filter.

I didn't observe any black smoke from the tail pipes. When it's running, it runs well. There's a voltmeter plugged into the cigarette lighter, and the running/battery voltage remained steady as it stalled and died. (normal alternator voltage, then battery voltage when it has died)

The suspects - coil and ignition control module. Were locked down here, otherwise I'd go get a loaner fuel pressure gauge and see if I could eliminate fuel system issues for sure before jumping into electrical issues.

Any ideas what to do next? Is the tach driven from the coil or ECU? What is that bleating noise just before it dies?

 

Both the ignition module(AC Delco D1906) and the coil are known to fail after absorbing engine heat. If it come down to a guess, either or both would be reasonable stabs.

If you have a DVOM you can test the the coild for about 1.0 ohm primary resistance and 8k ohm secondary resistance. Of course you'd need to test it while the problem is actually occurring

There are test for the module but the only one I can think of at the moment is to disconnect the two-wire plug and check the resistance as mentioned below in the "CEI Ignition" test:


The test assumes a fully charged battery

1) Measure voltage at coil "+" terminal with key "on". It should be within
one volt of battery voltage. If not suspect a problem with the wiring to the
ignition switch, or the switch itself.

2) Measure voltage at the coil "-" terminal. Result should be the same as at
the "+" terminal. If Ok, go to step 3. If not....
Disconnect the wire from the amplifier from the "-" post of the coil and
measure voltage again. Less than 2 volts means the coil is faulty. More than
2 volts means the amplifier is faulty.

3) Disconnect distributor pickup coil from the amplifier (this is the
harness from the distributor that plugs into the amp). Measure resistance
across the terminals. It should be 2.2k to 4.8k ohms. If Ok, go to step 4.
If not, replace the pickup.

4) Reconnect the pickup to the amplifier. Measure voltage at coil "-" post
while cranking engine. The voltage should drop. If OK, go to step 5. If
not, the amplifier is faulty.

5) Check distributor cap and wires, distributor rotor arm, spark plugs, coil
wire





Sometimes the ignition switch will act up although it usually is not heat related. Remove the under dash trim panel and, with engine running, gently jiggle the wires at the back of the switch. If the engine stumbles, you've hit pay dirt. Or.....run a jumper wire from the coil "+" post to the battery "+" post of the coil and then go for a drive. If the problem goes away, you have a faulty switch or a wiring problem from the switch.


If none of this pans out, post back

Cheers
DD

 

Tach and ignition signal to negative terminal of ignition coil come thru the ignition amplifier; signal to ignition amplifier comes from pick-up inside distributor. Intermittent pick-up (P/N AEU1721) problems have mostly to do with broken wires, so you can check leads for an open with multi-meter, while wiggling wires.

Both the ignition coil (P/N LU-BD198)and the ignition module (P/N Delco D1906) inside the Amplifier are subject to heat failure and both have the same symptoms you have described. They get warm and fail, only to work again when cold.

After checking pick-up wires, I would start with ignition coil if it is a few years old, as it is easiest to replace. Then go to Ignition module

Here is link that will help you if you have to change the Ignition module: Jaguar XJ6 S3 Ignition System Repairs:

Rgds
David

 

What happened. ugh, start a good story and then it stops before the "finis"page !!! Not fair!!

The jumpy tach is as god a clue as any that the issue is ignition related. A steady tach needle is dependant n a steady ignition pulse.

Ditto prior ignition suggestions. I am a great fan of the jump 12v to coil + processs..

Off to chores. Includes bill payments, ugh..

Carl

 

I love this board! Such a wellspring of information and helpful advice -THANKS.

I came up lame this morning with a gout flare-up so I've not been able to amble out to the shop to play with the Jag. Hopefully I can hobble out there tomorrow to do the recommended diagnostics.

Thanks again,

Phil

 

Phil
The pick-up in your distributor may be (P/N AEU1721) ( later) or (P/N AEU 1500) (earlier). If you look at SNG Barratt web-site and put in both part numbers one at a time in search box, you will see a different plug on the leads that goes in to the Amplifier. My 1984 used the (AEU 1500)
Rgds
David

 

David et al

I read the attachment you'd provided on rebuilding the ignition amplifier.

Since the car is 36 years old and it appears the coil and amplifier have remained unmolested since new, I'm going to take the opportunity to rebuild the amplifier with the PerTronics HEI unit and 'Flame-thrower' coil as recommended in Roger Bywater's paper. Roger's observation that the PerTronics components produced a 'significantly smoother idle' clinched the deal since my car has always had a little stutter at idle at traffic lights. Will do plugs and wires too.

I'm hoping the rebuild of the amplifier and the more powerful coil will solve the problem, but I'm going to start searching for a used distributor to rebuild too.(Thanks for the heads-up on the differences in '84) All I need to go is convince my wife that good social distancing in possible at one of the local self-serve junkyards so I can get out of the house. (Zero success in about the last five attempts) 'Everyday XJ' might be an option if I fail to escape.

Doug, David and Carl - thank you.

Phil

 

Phil,
Let me know your plan on repair of spare distributor ... I have file folder on tips from others, if you want to do it yourself... If you send it to one of the specialty shops for Lucas distributors, they will take care of everything.... configure it for your compression ratio, fuel octane, good fuel economy and test it. They normally have an initial static timing recommendation that is different from OEM to get best results.
Rgds
David
.

 

David-

So far I've been pretty light on diagnostics, rationalizing that all the parts on my Jag are 35+ years old and I should just replace them, so I bet on known failure modes and solutions.

I ordered the Pertronix D72000 HEI module and the coil recommended in the paper by Roger Bywater you posted - the parts will be here by Tuesday and I should know then if the Pertronix module and coil resolve the stalling issues. I have a new distributor cap, wires and spark plugs on the shelf to put in at the same time (will be interesting to see if this latest barrage of parts fixes my slight lumpiness at idle too, as Roger said it did for him)

While I'm installing the new cap and wires, I'll give the distributor shaft a jiggle and see if I can feel anything. At only 60K, miles, my hope is the distributor is fine. If it isn't I'd appreciate the name of the Lucas distributor rebuild specialist and your timing adjustment recommendations. (Have a couple of old MGs and some club members have recommended a Lucas rebuilder - it'll be interesting to compare notes)

Will post up the results of my latest parts 'shot-gunning' with the plugs/wires/cap/module/coil next week and go from there.

Thanks again to you (and others on this board) for sharing your wealth of experience and advice - it is much appreciated

Phil

 

Phil
Here is an E-bay core Distributor for full rebuild


Jaguar XJ6 Series 3 Lucas Distributor 41912A 45DM6 Dated 1986 OEM
Item ID: 303068614514 Buy It Now price: $35.99 Your offer: $26.99 Offer expires: Apr-08 15:34:09 PDT Seller: rw_auto_classics(3,053)

I would send to this Lucas Distributor specialist.

Jeff Schlemmer
17495 Marystown Rd
Shakopee, MN 55379 .................2-05-2014
612-804-5543

Jeff, please find the disassemble distributor from my 1984 Jaguar XJ6. This is a California smog-ed car and I need to be able to pass test next year. I have enclosed a Vacuum Diagram that reflects the way my car is currently plumbed. Please call if you feel it is beyond economical repair; It seem that I can get a used one for $ 85 that may be a better core.

“Dave, I specialize in ALL Lucas distributors. Your 45DM6 has plenty
of room for improvement and I can certainly rebuild it and tailor it
for your car. I have a good assortment of vacuum units here to choose
from, including a special setup for use with manifold vacuum that I
had custom made. One of those along with a full rebuild using a full
length custom made Oilite bronze shaft bushing, full rebuild with
re-curve, and a shaft modification to make it more serviceable in the
future will run around $159 plus postage.
If you want to send it in for repairs, I need the complete distributor
minus cap and amplifier box. Just unplug the 2-wire connector leaving
the cap and wires in the car unless you want them tested. I'll set it
up and provide new timing specs to use. Simply retard the timing to
stock specs to pass smog, advance it to my specs to make it run well!
Thanks, Jeff”


Note the date, the price may be higher now. Also you will need to add a new pickup with an advance mechanism base from SGN Barratt ($98) (P/N AEU1500)


Rgds
David McElroy

 

Success!!

The big brown truck brought my Pertronix ignition module and coil yesterday and I installed them this morning. Drove at temperature for about a half hour and everything worked fine.

Plug wires and coil looked like they might have been original to the car. The ignition box seemed unmolested since new too. I took me a minute to get my head around the Jag's cylinder numbering convention and distributor rotation direction.

Next S3 Jag I see on Row52 I'm going to snag the distributor for rebuild and make a spare out of the ignition box.

Seems to idle incrementally better with the higher output Flamethrower coil too - almost acceptable. I think the next step is to pull the injectors and have them cleaned, flow matched with new hoses and seals.

Thanks to all!

Phil

 

"I think the next step is to pull the injectors and have them cleaned, flow matched with new hoses and seals."
Phil
Flow matched injectors, all new fuel lines in engine bay and all new vacuum hoses in engine bay will give you a lot of peace of mind and satisfaction... and you won't be fretting over what kind of fire extinguishers is best for your daily ride.
All the best
David
PS: My injectors ranged from 19 to 24 lbs when tested...

 

I'm back. With issues. Need to tap the brain trust again.

Was at speed on the freeway again after an afternoon of running errands in the Jag - 84 XJ6 with 62K miles. Like the last time, ambient temp was about 105F. The engine started missing, but I was able to proceed about 5 miles to home. At the stop sign on the freeway exit, the engine stopped running, and I coasted into a parking lot to let it cool. After a half hour it started up and I drove it another 3.5 miles to the house, still missing and stumbling.

After the issues I'd had the same issues last April, I replaced the following parts and put perhaps 5-600 miles on the car. (I also replaced the AC compressor, receiver dryer, fan clutch and charged the refrigerant, but that shouldn't have made any difference)

• Fuel pump
• Fuel filter
• Petronix Flamethrower coil
• Petronix ignition module
• Plug wires
• Bead blasted plugs and re-gapped

The car exhibited the following symptoms-

• The tach started to drop intermittently to zero from about 2300 RPM, but I was still able to maintain 65 MPH
• The tach pegged to redline and stayed there, but there was no indication that the engine had actually sped up. Running a little rougher but still able to maintain 65 MPH
• The engine stalled at the stop sign at the end of the exit ramp. It would start right back up, but start cutting out again and stalling at lights.
• Engine temp was 85C and voltage steady at 13.8V. AC was off.
• I could keep the engine running to pull it into the garage with one foot on the brake and the other on the throttle
• Pulling into the stall, each time the tach would drop RPM, there was moaning/honking sound coming from the car.

It is hard to fathom a failure of the Pertronix coil/amplifier after only a few miles. Will jump the coil to battery tomorrow and check the integrity of the wiring amplifier/coil and see what happens before i go any further, but then on to the distributor.

Any thoughts on moving the amplifier out of the engine bay and onto the forward side of the radiator support?

There's an 86 XJ6 at the local pick and pull junkyard, and I can pick up a coil/distributor /amplifier for just a few bucks - is an 86 distributor suitable for an 84 engine? (was there last week and there was a federal car with 7" headlights - bought everything needed to convert mine to 7" for $20 - looks like I'm going back for the distributor)

Any thoughts? What's the moaning/honking noise?

 

There is a little-known fault on the fuel injection system that caught me out in the 90s with my 1980 Series 3. After the engine has started, the fuel pump relay is kept closed by voltage supply via two tiny contacts in the Mass Flow Meter. These can fail to make contact intermittently as the car gets old and older. It is a pretty stupid way of stopping the fuel pump if the engine stops but there you are, we must live with it. Incidentally, these contacts are bypassed when the engine is being turned over with the starter motor. Symptoms are pretty much as you describe; the engine stops, you then manage to park the car by the side of the road and it then can be started again.
Anyway, how do you know it is this fault ? Well, (as told me by a Jaguar shop), you get a couple of long wires, and secure a clip on one end of each wire, and solder the other ends onto a 12v bulb. The wires must be sufficiently long for them to be clipped on the fuel pump terminals and then lead back into the car so the bulb is visible to the driver or a passenger acting as an observer. When the car is running OK the bulb will be illuminated, but if the tiny contacts in the MAF play-up, the bulb will go out.
It is explained by Roger Bywater who was at Jaguar when the fuel injection technology was being installed to the Jaguar engines in the 70s.

Fuel injection and the Jaguar XJ6 4.2 Series 3 / AJ6 Engineering

Look at Section 3. There is a paragraph just before "Airflow Meter Problems that describes the fitting, then immediately in the Problems section the fault caused by these contacts is described. These contacts really are tiny !

Of course it may not be any of the above, but probably worth checking out, bearing in mind my car was 12 years old when I had the problem and yours is now 35 years old.

 

That's what I would do, and/or gently jiggle the wires at the back of the ignition switch.



Can't hurt, might help.....if no firmly identifiable fault is found.



Yup !

Oh, there might (or might not) be some very subtle different in the advance curve but nothing that would prevent you from using it. But.....the components of the Lucas CEI are not happy with excessive heat, either, especially as they age. The GM ignition module (inside the amplifier) is notorious for failing with heat....and absorbing a lot of heat will often put an old Lucas or Ducellier coil over the edge as well.

Cheers
DD

 

Ahhh, very clever !

As an alternative I would first bypass the entire fuel pump control circuit by bypassing the fuel pump relay....which is quite simple. If doing so alleviates the problem then the test you've described is a great way to narrow down which specific branch of the circuit is causing the problem.

(PSA: Some owners have bypassed the switch in the Air Flow Meter. This allows the pump to run whenever the key is "on". This is a dangerous arrangement; I wouldn't recommend it.)

Cheers
DD

 

Thanks for all the input and advice.

Too hot already today to pull the distributor out of the wreck at the yard, but plan to be waiting at their door at 7:30 when they open tomorrow. I had a timing light that sat in the drawer of my tool box for years that I'd never used, so I gave it away. Hoping that Autozone has one in their tool rental program.

Going to take my dykes with me and harvest some bulb sockets to make some jumpers too

The $2 admission to the self serve yard is one of the best entertainment values for gear heads. There's a website where most of the self-serve yards post their inventory called Row52.com. You can request an email notification when something that interests you comes into a yard within a radius you specify. I get email notifications for S3 XJ6s a few times a year and hop in the car and check them out.

 

Haven't been on a boneyard prowl in many years but it used to be a pretty regular thing. And it IS fun ! I always came home with more than I originally went for. You always find some goodies and treasures

Cheers
DD

 

My available rolling-stock that actually runs dwindled down to just the Toyota Highlander, so it was time to take another stab at getting the Jag to run reliably.

I'd parked it in late August - it was just too stinkin hot to mess with it.

The weather now is just beautiful again in Arizona, so time to get back on it.

Replaced all the brttle wires going to the amplifier, replaced the condenser in the amplifier box and checked the resistance of the pickup coil in the distributor. I drove it about 10 miles and it started acting up again - RPM would drop intermittantly and it would act like it wanted to stall at idle.

Pulled it into the garage and started getting ready to pull the distributor and replace it with my junkyard find, reasoning that the only thing I'd not replaced was the distributor and there's the possibility I had an intermittent connection in the pickup coil.

When I started to pull the plug wires out of the cap, the whole cap and wires came off the distributor - it wasn't even screwed down. It is a wonder it ran at all.. The noises I was hearing when the RPM would drop was the distributor rotor rubbing on the cap, I think. Looked pretty knackerd inside the cap.

I tried fitting a new cap and rotor, but couldn't get the screws to start. After chasing the cap threads in the distributor, the new cap and rotor went on fine. Evidently I'd put the cap on when I changed the plug wires and thought it was tight - it wasn't.

Seven mile test run to pick up cardboard boxes at Lowe's - ran fine. Will take it out again today for some more milage to make sure it behaves ok. Sold our house in Phoenix and have our eye on a house in northern AZ - no emissions test there, and the house we're angling for has about 2000 SF of garage space - fingers crossed it all works out. Might be payback time for those kids who left home only to come back to mom and dad's - we might have to live with them for a couple weeks!