My '94 Died At a Stoplight and Wouldn't Restart

XJ40
1

First the moral of the story, then the story: replace your CPS (crankshaft position sensor) before it dies - or at least carry a working spare!

Yesterday evening, on my way home from my office, rush hour traffic, busy intersection on a main thoroughfare, and as I pull up to stop at a signal light the old girl dies on me. Crank, crank, crank, no start - and no blip on the tachometer. An under-hood inspection did not reveal any damaged wires or loose connections, so I needed to replace the CPS. I set about preparing to do just that and in short order a couple of nice local constables arrived on scene, having been notified of the traffic snarl I was causing. After I told them I had a spare part with me and the necessary tools they suggested the car be pushed to a parking lot that was probably 100 yards distant. While one officer directed traffic the other rolled up his sleeves and while I piloted he pushed me through the intersection. Fortunately there was a downhill slope leading to the parking lot so off I went. Long story short, I swapped in the used CPS I carried with me. This was the CPS - probably original to the car - that I took off and replaced with new when I replaced the head gasket, valve stem seals, hoses, etc. at 95k miles - 93k miles and 17 years ago. The car fired up, loose ends were buttoned up, and I continued my journey home where a nice cold cocktail awaited me. Whilst slaking my thirst and licking my wounds (hard to do at the same time!) I jumped on the InterWeb and ordered a new CPS. When it arrives I will install it - to make sure it is good, and for the sake of reliability - and relegate the used CPS to backup duty. Meanwhile, I am running on the old CPS, which at least allowed me to make it to my office this morning.

Interestingly, in hindsight, there was a warning sign that the CPS was dying. Yesterday morning as I drove to my office there were a couple of instances when I pulled to a stop and the idle dipped to 500 rpm for a couple of seconds, then recovered to normal (~650 rpm). I have not heard of a CPS causing this symptom - the usual is a failure to start - but I’m convinced now that the CPS was the cause.

So, in conclusion, I have once again found my boyhood Boy Scout leader was correct: Be Prepared!

2

Great story.

I own a 1993 U.S. Sovereign, and I have one question.

Do you keep the electronic spares in the glovebox or under the center armrest?

Thanks!

Rick Ransier

“…home before dark”

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You’re right Mike. I’ve also experienced the RPM drop and recovery, though not in a Jaguar. Its not the easiest thing to recognize, because as you said, that’s not a typical symptom.

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Actually it is [C], neither of the above! I keep spare bulbs, splice connectors, electrical pliers, and tape in a toolbox in the trunk (boot). A spare distributor cap and rotor and CPS along with my Haynes manual and sundry maintenance and repair info I’ve accumulated over the past 19 years are in a tool bag in the trunk. I forgot - I do keep spare fuses in the center console cubby. My '94 model has no glovebox, it was instead fitted with a passenger airbag (a/k/a Supplemental Restraint System or SRS).

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Mike …

I’m going to take your advice and although I’ve had no problems I’m going to replace my CPS as preemptive strike. Easier to do it now in the comfort of my garage rather than by the side of a busy highway in the pouring rain, on my way to collecting my lottery winnings with time running out to produce my ticket. :smiley:

By the way, did you get the names or badge numbers of the helpful “constables”? It sound like an attaboy sent to their boss may be in order!

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Grooveman I must sadly admit I was remiss in this regard. I thought I would have an opportunity to do that once my car was safely off the thoroughfare but because I was on a roll (literally) to the parking lot the nice chaps stopped at top of the incline, watched to make sure I got safely onto the lot, then turned sharply on spur-adorned heels, returned to their waiting steeds, and rode off into the scorching evening sun. I do recall hearing one of them let out a cry that sounded like “My Hoe is Gilded” or something to that effect so perhaps that is a clue. :sunglasses::rofl:

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