Ok, I'm going to rephrase the problem from how it was posted before because I think the speedometer issue is completely tangential.

My 1995 XJ6 is experiencing a loss of ignition/power problem. The car runs for however long it takes for the engine coolant to reach 170degrees and at about that time the engine begins to miss or stutter occasionally at first. With every stutter the instrument cluster flashes off and back on as though the car is being restarted.

To date I have checked all of the ignition relays and they are good (there are several). I have removed the steering column and checked all of the wiring going from the ignition itself. I have replaced the ignition. I have replaced the speedometer cluster, I have replaced the transmission computer. I have cleaned and tightened every ground post I can find (MANY). I replaced the MAF, just because I had a good spare. And yes, the battery posts are clean, the battery is new. I cleaned the engine position sensor connectors as well.

I'm not really sure what to look at or for next.

Any more ideas?

Thanks

 

Jack,

You still need to follow a diagnostic process to whittle down the possibilities. Your symptoms seem to suggest a poor ground or an interruption in ignition power. You feel you've covered the grounds, so lets concentrate on the ignition sources. There are three ignition relays I think we should center on. RH engine bay fuse box, LH heelboard fuse box and the trunk fuse box, in that order. Each has a single relay next to the fuses. Get a jumper wire made up with a spade terminal at each end, ones that match the terminals on the relays. What we want to do is substitute a jumper for the relay, one at a time, and see of the car will run beyond the 170 deg. temp you have trouble with.
First turn the ignition on, then pull one of the relays, then connect the jumper across the terminals in the fuse box. Two of the relay terminals are parallel to each other, forget about those, we want the ones that form a "T". Connect the "T" terminals and then start the car. Do that for each of the relays until we hopefully find one that will let the car run when it's jumpered. If we find one, then we can concentrate on the relay circuits.
Give it a try, what have you got to lose??

Good luck!

 

I have a brand new relay in the RH engine bay spot. That doesn't exactly answer the question does it?

Ok, bypass the relays. I will try that next.

 

Your car has infected my car, damn they are good cars haha.

Cold start after 2 days of no use.

It started running "odd", sort of lumpy cam type idle as soon as the temp gauge "cracked" the Blue sector, and the exhaust STANK. Leen fuel smell, NOT cat convertor smell.

NO CODES.

Gave it a blip on the throttle, smoothed out for a second or 2, then started again to get lumpy, then it smoothed out to "normal", and the temp gauge was about 1/2 way to "N".

Temp sensor swapped, so tomorrow will tell I hope.

Next will be the O2 sensor/s.

The cats are getting tired (166k kms and 15 years old), so they will be removed when I get time.

Not the same as yours I know, but from what I read all your issues started AFTER the column work, correct??. I just cannot find anything in the ignition "supply" circuit that is temp related.

 

Oddly enough though Grant the two problems may be related. I'm replacing the CTS this morning at the advice of my local mechanic. He is thinking that it is causing some kind of feedback into the BCU that's causing the car to think it needs to shut down, but only intermittently. I have all those symptoms you mention (lumpy idle, fuel smell etc...) AND it all is consistently connected to the coolant temperature arriving at 170. Closed loop fueling. What if the CTS is malfunctioning and dropping the car in and out of the closed loop and it is causing miscommunication with the ignition system?

I'm trying that because the sensor was available and cheap, and I'm also going to try the hardwired relay trick today.

We shall see.

 

Jack,

Mine is SWEET today.

CTS fixed the beast, apart from an odd exhaust smell, which I do reckon is cats, so hacksaw, piece of pipe, mig welder, under we go and ATTACK. Let you know in few days when I surface.

 

The new CTS came in, wrong connector, sad day. I ordered one from another supplier I like, again, wrong connector. This one I whittled on to make it fit. I did well with the fitting. The car ran well past 170 coolant temp without ever once flashing or stuttering, but once it reached 185 it stuttered every 5 minutes or so and the binnacle flashed.

Concurrent with all this, I had to replace the battery again. Will it drain a battery for the car to be running and sitting still? What if both the alternator and CTS are going down at the same time? How can I isolate which is what?

Thanks!!!!!

 

Jack,

A battery simply WILL NOT drain like that, unless it is a dud, ??, something is draining it whilst the car is supposed to be OFF (or asleep).

I had a moment of madness today, and decided to take the MK10 for a 'blast", now it has sat for 3 months, battery connected (must have had brain fade when I last used it), and it fired straight up, of course, its a Jag, mmmm. Now that battery would be at least 4 years old.

I would like to see a "sleeping" amp draw on your car, that should only be 0.5 amps or very close.

The CTS is not consuming power unless the ignition is ON, then it is only a 5 volt ECU signal that it "splits" via the thermistor to give that ECU the temp reading for the fuel map. Very simplistic explanation, but it will do for this exercise.

Now the alternator is a different beast. That sucker has a BATTERY cable attached to the bolted post, and that is LIVE at all times the battery is connected. So if there is a diode, or a voltage regulator (both inside the alternator) leaking to earth (they do that at times), there is your battery drain, and MAYBE your problem.

Follow this for a minute.

IF, and this is a big IF, that alternator were "overcharging", it would take some time to replace what was used to start the car (time related not temp) and once it gets to a certain point the "overvoltage" is causing the ECU to "shut down". I have NO idea what, if anything these cars have as an "over voltage" protection circuit???????. The ECU's are very reliant on "stable" voltage supply, and do wierd things when that voltage is outside their working parameters.

A lot (and I mean a lot) of years ago my Citroen did that, and they had NO gauges as such, so I had no indication of what was really happening, but that "over voltage" exploded the ignition coil, engine stopped, much testing, and once found simply fixed. A simple aftermarket volt meter kept an eye on things after that, but as usual nothing went wrong again.

 

At this point, I am certain that the battery is good. As of now, whatever was an intermittent problem is a full on beast.

The car will not even turn over. I do not even hear a click from the starter. I got it to start once last night just by trying several times. Today I can get nothing.

Where do I look now?????

This thing is curiouser and curiouser. The ignition relays are all new.

I never even got a chance to jump the relays to see where the main issue was.

 

Ok, quick update. I did some forum research. I went out just now and treated the gearshift a little rough and firmly put it back up into park and on the first try the car started. I think I know what that problem is, but I need to know now how exactly to adjust the gearshift properly so that it doesn't prevent start again.

Could something here be the whole doggone problem??? Something in the gearshift that prevents start that causes the car speedo to flash????

I love puzzles, but this is more like an exorcism.

Thanks again everyone for the input.

 

OK, neutral start switch.

It is relatively simple to adjust, remove the ski slope, look on the RH side of the gearlever base and you will see a switch pack attached to the unit. It has slotted holes and adjustment is straight forward. Part Number LNA6550BA (they call it a Linear Switch) on "Classic Jaguar Parts" website, which has a drawing showing how it all fits, simple really.

I do not see how it could cause other issues, but anything is possible maybe, but it really does just close contacts to allow "crank", and then another section switches on the reverse lights when in that position. I THINK hahaha, that in "D" it also allows the cruise control to actually be used, at least it did on the XJ40, and this area is the same to look at, but the schematics may be different.

These switches do play up, as they fill up with "muck" over the years, so bite the bullet and remove it, give it a good clean, refit and adjust, forget for another 10+ years.

Proper setting of this switch is a GOOD idea, at least it will eliminate it from the system.

 

Interesting update. Today I installed what was supposed to be the proper CTS on my jag. I let the car run for an hour and 10min. The speedometer didn't flash once. However the car finally stuttered and died. Then about an hour or so later I gave it another try. This time after about 45min the speedometer flashed. It did it a few times and then the car died.

Why did the new CTS only change circumstances for a little while and then have no effect?

 

Bugga, I thought you had it there, until I read further.

I am now leening toward ECU, no specific reason, but it seems as all the info for the car comes or goes via that unit.

How long ago did all this issue start, was it a gradual thing, or all of a sudden??.

The speedo flashing without moving is odd. Tacho I could understand.

 

Grant, I need to be more specific. When I say speedo, I mean the whole ipac, binnacle, instrument cluster. Every gauge on there that shows a reading drops to zero as if the car ignition has been manually turned off, then all the lights come on just as they do at start and then the gauges return to normal. The speedometer itself doesn't move since it is sitting still. I just used the word speedo to describe the whole shebang, sloppy I know.

Oh, and also when this thing first started it was an occasional stutter in the engine with no flash and no die at idle. Then one day as I was driving down the road the ipac flashed once on me. After a week or so it was more. Finally it got to the point where the car would die at idle just about every time I stopped at a stopsign or redlight.

Also when the instrument cluster/binnacle returns to normal the odometer says AIRBAG and the red SRSairbag light comes on too. That has been consistent from the start.

No codes register with the OBD2 reader whatsoever. However the climate control does show a code 11, which the book tells me is a nonspecific code but only involves the AC/Heater.

I don't know if the car dying is even connected to the ipac/binnacle flash, but they seem connected in time.

I feel like something is going to ground (just a gut feeling), but I don't know where else to look. I have checked every wire I can find without disassembling the entire ignition harness.

Why would it behave fine with the new CTS and then start off down the wrong road again????

 

I did a write-up on this fault a few years ago on another forum and the person reported back that it fixed to car.

I worked at a dealer until several years ago and a 1996 XJ6 with high mileage came into the shop with the EXACT fault. We drove the car with WDS plugged into the DLC to monitor the ECM. When the engine stuttered and the INSTPK 'blinked', The WDS computer also lost connection/communication with the ECM (Like the engine was shut off and back on). After hours and hours of diagnostics we finally realized that an 'on-plug' coil was arcing/shorting and causing a massive voltage spike to the ECM and shutting it down, stalling the engine.

We took a new coil and kept moving it to different cylinders until the engine ran smooth and did not backfeed the ECM and cause the 'stutter/stalling'

My advice is to get a good used or aftermarket coil ($75 from Motorcars LTD or other online source) and put it on cyl #1 and drive, move it #2 and drive, etc.

Just an anecdotal story of my findings throughout the years of 'strange faults'.

This may or may not be your problem but it is something to consider.

bob gauff

 

Sorry motorcarman, I was wrong.

I took all the coils out and looked in the wells. The coil nearest the firewall was kneedeep in oil. The gasket around the sparkplug has leaked at some point and I will need to replace it. I cleaned it out, cleaned up the coil-boot, extracted the sparkplug and cleaned it too. The car is flashing, there is still backfeed.

HOWEVER, I do have a question. Should you be able to see the spark flashing in the top of the gel of the coil? I can only see it on the two nearest the firewall. Is this an indication of a diffusing coil?


As of this evening the car is still flashing after it reaches the CTS max temp. This CTS appears to be 165. For each CTS I have had, it has been a different temp at which the flashing began which also happened to be the highest temp the car would reach before eventually stalling out.

The coils are all new, I do not see any carbon, but as I said I can see a flashing light in the top of two of the coils. This isn't normal is it????

 

Jack and all, I have read through the two sections describing your problem - also my 1996 XJR's problem. I ended up replacing all the coils but the dash will start blinking off and on after about 45 minutes driving. It all started when I took a serious passenger side wheel hit at 70 in the dark after some construction cones had ended on the freeway. Two interesting things; when mine goes dead, often the Check Airbag light will stay on - then off with the next flash cycle. The XJR does not stop running when the dash is going haywire - sometimes will hickup. I am wondering if the engine kill switch was part upset with the wheel hit and/or there is something in the Airbag circuit that was partly set off.

 

I edited my last post, but I should also state here that the problem is ongoing with the flashing binnacle.

Thanks to Fife, the next thing I am going to look for is the airbag sensor in the front bumper.

 

I would think that the 'flashing' in the top of the coil is not normal. The energy should be going to the spark plug, not the coils of wire in the windings meaning you shoud not see arching IN the coil. I would try replacing the 2 offending coils (used or borrowed) and see if the fault reoccurs.

bob gauff

 

Apparently the flashing in the coil was an indication that the coil was diffusing before it charged the plug and was back feeding into the ignition system.

Whatever it was, replacing three of the coils with ones I knew to be true did the trick.

Next thing I need to know is how to make the lights come on properly on the shift box.


Thanks again to everyone for their help!!!!!