I took out X300 out for lunch, and on the way back experienced several strange things happening.
First, several times at highway cruising speed (~70MPH / 112KPH) the whole car would “buck” as though the engine suddenly cut out and then restarted. On one of the last times this happened, I did see the tach drop from about 2500 to about 1500 RPM (before picking back up at 2500).
After just getting off the highway, the car stalled as I stopped at an intersection. Several times in the next couple of miles, the car died again but I was always able to shift into neutral and restart the car. Oh yes, after restarting at the intersection stall, the “X” over the transmission and check engine warning lights came on.
Finally it got to the point where the car would not restart. I was able to coast into a parking lot at which point I made several more attempts to start the car. It always sounded like it was just about to “catch”, but never did. BTW, the tach was reading ~200-250 RPM so I don’t think it is the crank position sensor. (Unless they die intermittently
I was able to get the car towed home, and of course, it started right up in the driveway. All the warning lights went out as they normally would.
Any ideas? I have a few, but after running in the driveway, I’m not so sure.
I have written a long post years ago about the On-Plug coils failing and causing electrical ‘spikes’ to back-feed to the ECM causing a momentary ‘shutdown’.
A buddy at the Jaguar Dealer I worked at actually discovered this while trying to determine the intermittent ‘shutdown’ of a (X300) customer car with 240,000 miles that was otherwise a decent running car.
He called me over to watch a WDS datalogging session in which the ECM seemed to momentarily go ‘OFF-LINE’ and blank-out during the session when a ‘misfire’/stumble occurred.
We watched the several sensors on the data screen go BLANK when the ‘stumble’ occurred. The ECM shut-down like the key was shut-off momentarily. WDS stated LOST COMMUNICATION.
The AJ16 DTC monitor is not very reliable at detecting misfires so it was difficult to determine the exact cylinder causing the fault. Examining the coils gave us a clue to the offending part. We concurred that the ECM went ‘off-line’ at the exact moment of the misfire and some of the plastic cases had cracks and signs of arcing so we thought they might be causing high voltage problems for the ECM.
The car was relatively new (only 4 or 5 years old) and the customer wanted ALL the coils replaced at a cost of almost $1200. He was tired of the intermittent faults and wanted the car back.
He replaced ALL the coils and the engine ran normally.
I have written a long post years ago about the On-Plug coils failing
and causing electrical ‘spikes’ to back-feed to the ECM causing a
momentary ‘shutdown’.
I do dimly remember your post (and other coil related posts).
It is certainly possible, as the car has about 150,000 miles. I’m the
third owner (purchased the car used from a Jaguar dealer where it had
been serviced about three years ago) and as far as I know, the first
two owners had the standard dealer maintenance / repairs done. So I
don’t expect any after-market coils to be present. But never say never.
I’ll see if I can make some time to check the coils this weekend.
5 of the 6 coil packs have cracked (in at least two places) upper assemblies
(the coil itself). One of the 5 also had oil on the tip because there seems
to be oil pooling in the spark plug well. Sigh.
I think my first task is to replace the coils with cracked cases.
In addition, I pulled three diagnostic codes:
P1775 - Possible transmission fault
P0430 - Catalyst efficiency below threshold (O2 sensor?)
P0727 - Engine speed sensor low (engine stalled while driving)
I think the P0727 may be the cause of the P1775, and possible the stalling
and restarting may be the cause of the P0430. None of these codes appeared
prior to the problems last Thursday. (I like having the DTC Summaries
manual
Once I get the coils sorted, I’ll clear the codes and take the car out for
a test drive.
Oh yes, it is possible the problems may be temperature related. The past
week or two have seen higher temperatures; low/mid 80s to low 90s (27C - 32C)
here in southern New Hampshire.
As a ‘quick-fix’ you might try to coat the coil bodies with some sort of plastic epoxy or insulating material. A thin coat might extend the life of the coils???at least until you replace the CKPS and see if that cures the stall.
If you do buy replacement coils DO NOT buy cheap After Market ones either get new OEM ones or look for guaranteed used ones on Fl*abay or a breakers. Cheap ones cause more misery than they are worth.
In your experience, does this sensor fail intermittently or a solid failure?
When my car was not starting, the tach was showing about 200 - 250 RPM. From
what I have read in the forum, this would seem to indicate the sensor is OK
(at least at the moment).
DO NOT buy cheap After Market ones
From the horror stories I’ve read, I am going to either do new or good ones
from a wrecking (junk) yard / breakers.
Just for ‘grins’ I swapped out a good-used CKPS. TA DAH!!!
I’ve got a couple of good used coils arriving shortly; which only leaves
two more for a complete replacement. I ordered new coil gaskets and a
new CKPS from Jag-Bits, so I’ll have that on hand as well.
Interesting reading this as I was on a club run a few weeks ago and the car was driving normally, SWMBO and I share the driving, she drives out and I drive home and there was no problem while she drove that I could detect.
Just once on the way home it felt exactly as tho the ignition had been momentarily cut. No warning lights and the car ran faultlessly for the rest of the journey.
I do have the occasional stumble when sitting at a set of lights when a misfire occurs. Might be in line for a new set of coils and plugs, not sure what state the plugs are in, the car has 79,xxxmls so they have either been replaced or are due for it.
The coils, gaskets, and CKPS all arrived today. So in they went.
It was a little interesting getting the old CKPS out, and it was pretty
covered in road grime (dust, dirt, and oil). Yuck. I’m going to do a
little testing to see what I find.
After starting it up and running it a bit in the driveway, it doesn’t
seem to run any differently. A short road trip is in order to try and
shake things down.
I wonder if all the road grime might have something to do with it being
a bit intermittent. If there were some bits of metal stuck to the magnet,
I could imagine it might not work as designed.
I’m also going to put an oscilloscope (since I have quite a few, being an
amateur radio operator as well as a test equipment “junkie”) and see what
the coil wave forms look like. It should be interesting.
