Much loved, well cared for XJR 177,000 klms. After about 40 mins of normal driving in normal conditions, 'Check Engine' light blips but does not latch and stay illuminated. This re-occurs 2-3 times then all dash warning lights come on, all gauges go to zero. Lights go out, gauges come back, cycle repeats, car continues to run. When dash lights go out and gauges read normal, AIRBAG is displayed where trip readout is and SRS red warning light on bottom right display. Noticed engine revs elevated during this condition, revs not falling off smoothly when slowing down to a stop, i.e reluctant to drop below 1000rpm. No CEL no retrievable DTC's.

WHAT I'VE DONE SO FAR!
Checked battery voltage levels both static and charging 12.7-14.6 dc volts.

Checked all grounds/earths.

Removed and inspected ECM/ECU Module part# LNB 1410/401 looked for dry/cold soldered joints, dried and open electrolytic capacitors.

Checked Temp Sensor resistance readings over working temperature range.

Remove and inspected CPS, checked resistance reading (heated with heat gun to check for open winding when hot). Checked peak mV reading passing steel across pick up head.

Checked resistance of TPS and smooth response through working range. Repaired damaged insulation on wiring.

Changed fuel filter.

Swapped battery.

Checked current draw on fuel pump (5.7-6.25 amps).

Checked all plugs male/female for corrosion, non found, sprayed with contct cleaner.

Unlike my 1993 XJ40, the XJR will still idle when, MAS, TPS, Temp Sensor are unplugged. XJ40 stops dead! is this normal?

Gentleman/Ladies, I would appreciate any input.
Al, BC, CANADA

 

Put the old ignition coils back in . You got some AC in the DC wires

Check the alternator noise suppressor ( capacitor )

 

Thanks Lady P. I will disconnect the capacitor (I'll check the TV for interference) and see if the car runs past the 40 min line! Not the easiest component to access is it? You might think the battery voltage would be sucked down by this, if the cap was bad, I've monitored it with a decent Fluke Multimeter. Should of added the car stalls out and idles rough during these episodes. Runs perfectly up to these blips.

Really Appreciate your interest and input,
AlinBC.

 

The cap is inside the black housing under the car , the housing splits in half with the tabs pulled outward with a 4 butter knifes to see it so you can put a heat gun on it directly ( or cooling air as you drive ) . If the dielectric shorts at a point in the wrap the cap rating changes before short causing a change in the filter frequency . Coils ? The large ground strap by the starter ? The data bus wire ( Red 10 at ECU ) as a multiplex system out of the ECU is the orange one , does the socket have grip or sprung/missing tabs .

Hope this helps , Parker

 

I have not touched the coils during this fault. Had one go bad about 4 years ago, misfire, flashed up a DTC which pinpointed the exact one. As I say, no Check Engine light and no DTC's with this sucker!

Thanks Again,
AlinBC.

 

edited above post

 

Your flashing IP is telling you it is time. PUll the coil cover and fire it up at night, I suspect you'll have a nice lightning show. May be temp-related which would explain the 40 minutes, but that is a little-known but classic symptom of coil failure.

 

Lady P and aholbro, Thank you both so much! The problem was indeed the coil packs or rather singular, coil pack. Number one, sparking away which, incidentally was the same one that failed last time (April 20th 2011) I purchased 2 at the time (aftermarket) so I had a spare on hand. Guess I may still have a problem with communication ECU to Inst Panel as this coil failure did not set a DTC but, at least the car is now reliable.

Thanks Again, AlinBC.

 

As long as you have the instruments I would leave it lone . If not I would simply disconnect the battery as a least intrusive try ( both post off and cables not connected to each other ) for about 30 seconds as this my reset somethings . Hard Reset later ( after resolved engine ) if needed as this will throw the engine off until it relearns some things . The bad coil probably gave you some " dirty electricity " down some wires . Mine blew a instrument fuse by me hooking the battery up backwards .

Thanks Aholbro1 as a experienced master steps up , Parker

 

These cars are reluctant to set misfire codes. And it could be possible you didn't actually have a misfire. Just some electrons escaping the coil to other places in addition to firing the plug.

Can't begin to explain how a failing coil causes the IP to flash, but just accept that it does.
There is a 6 million page post here on coils, usually on page one, but may've slipped a few deep lately. Excellent read, but the jist of it is: "buy the "Lucas Made in Japan" coils or plan to buy any other coil regularly"

 

Interesting! I see a huge difference in prices on these coils. SNG Barrett offer a choice of 3, an OEM at $266 (US) each, Made in Japan Aftermarket at $98 (3year warranty), and a no name at $40 ($34 at XKS Unlimited). I'm thinking you favour the $98 Jap over the rest?
Thanks Again for your help with this,
AlinBC.

 

I personally favor the used OEM from Pick-n-Pull for $9.99 ea! (less if you catch an X300 in the yard on half-price day!!!

 

Hello,
Just a note to say my XJR runs perfectly now. Prior to replacing the defective on plug coil, but before the inst panel gauges started going haywire, I always had a 'Faults Pending' amber light when I scanned with my OBD2 scan tool. Now, the scan comes up clean with a green light. Used Jaguar parts are pretty thin on the ground in my neck of the woods aholbro1 (this aint Texas!) in fact they're as rare as 'Rocking Horse Poop'. I see Welshnet has a pack of 6 at around $100 so I'm thinking of getting those as back up spares. So happy to have the car running well and reliable. So grateful for the help from Lady P and aholbro1, you've saved me hundreds of dollars.

Sincerely,
AlinBC.

 

Just always look for hairline crack running lengthwise or burned looking areas and pass on those...and try to pull from wrecked cars since you know they at least ran. Love finding a nice set of "made in Japan" Lucas!