My other thread got closed. Anyway ... Re-posting


So today, on the way home, I got stuck on the freeway in 5mph creepy crawly traffic - I could literally see my exit lane about 1/4 mile away, when the car died.

Pulled over and attempted to start it ... crank crank crank - no fire.
Then I saw I had my code reader in the back seat, so plugged it up ... P0727 thrown. I did a quick Google search while sitting there, contemplating my fate - having to call a wrecker to tow me 1 1/2 miles to the house.

Then I thought, "let's clear the code and try again" (after having sat about 10 minutes). Clear the code and she fired right up and she brought me home without a miss.

I found this in a past post on the subject:
Quote:
... Crank shaft sensor gap between sensor crankshaft on mine was greater than .047 adjusted spacing to .025 solved my issue with ckps . Even bought a new sensor didn't help till i adjusted spacing ...
So, I've read if you crank the car up and the tach doesn't move, this a sign that the crank-position-sensor is going out. I tried it ... crank crank crank, no sign of movement with the tach, but then the tach jumped up and the car fired up like nothing was amiss.

I sprayed the sensor at the crank ring with electronics cleaner, to include disconnecting the plug and spraying it too ... she fires right up now (she's been cooled down for at least an hour+).

So anyway, back to the quote ... I dont see any sort of adjustment for the gap for the CKPS ... I have removed it to take off the damper (about 3-4 months ago), and dont remember any sort of adjustment. I measured it with a flat-blade gap gauge and it's about .040".

Any thoughts ?

So, as a follow-up, I removed the passenger side (US) kick panel, disconnected and unbolted the ECU ...

The connector plugs and the receptacles on the ECU look brand new.
AAMOF, the ECU has a "do not remove this label", dated May 12, 2010, AutoComp Technologies ... so I assume it's a rebuilt unit.
Ironically, AutoComp is right here in Houston

Anyway, plugs and receptacles look great.

 

I usually hate advice to change parts without a clear diagnosis, but since the CranK Position Sensors are relatively cheap, I might try another new one. And, to your question, I do not remember an adjustment, but you could probably get a few thou just "encouraging" the bracket as you tightened. Or maybe a lil work with a rat tail and flat file!

 

Thanks Ross ...

I've had the car sitting (great excuse to ride the bikes ) till I decide what to do ... I start her up a couple times a day and watch the tach ... the tach jumps as it should. I disconnected the CKPS and sprayed the connector with electronic cleaner, to include the CKPS itself and the crank ring.

One thing left to do is to get the ohmmeter out check the CKPS for proper resistance and voltage.

Heck, I might run up to the grocery shortly and see how it works out. But yea, I've already checked stock on a local Jag parts house and they have one for $135.

 

Just to chime in, the CKPS is one of the few essential spare parts to carry in a Jaguar saloon, so given the iffy history of your CKPS, I'd echo Ross' encouragement to go ahead and install a new one. Put the old one in a Ziploc bag to seal out moisture and keep it in the trunk/boot as a spare to get you home when the new CKPS peters out.

Regarding the $135.00 price, you may find an even better deal at a local O'Reilly Auto Parts or other major chain store. Within the past year I bought a CKPS at O'Reilly for about $110.00. I called them in the morning and they had it that afternoon.

Regarding CKPS adjustment, as you've observed there is no provision built in to the design. The CKPS bracket is located on the timing cover with close-tolerance hollow dowel pins through which the two mounting screws pass. Adjusting the bracket even a few thousandths would not be easy (and should not be possible). The only way to adjust the gap would be to add a washer or spacer of some kind around the body of the CKPS to increase the gap, or to remove some material from the underside of the CKPS integral mounting tab to reduce the gap. I think Ross is right that the ECM doesn't care about minor variations in gap. The main thing is to ensure that the bracket and CKPS are free of any gunk and that the CKPS is fully-seated in the bracket before you tighten the mounting screw.

Cheers,

Don

 

Thanks Don, for the thorough explanation and Oreilly suggestion. The $135 piece at Motocars LTD is an official Jag CKPS ... I'll take it you have confidence in the aftermarket unit that is sold at Oreilly?

At their site, I see a number of listings - the "$110 unit" is:
Import Direct Ignition - Crankshaft Position Sensor Part # 19-0529
There's also a Borg-Warner Part # CSS941 (no price - have to call the store).

Oddly enough, in their list, they have a Camshaft Position Sensor erroneously labeled as a Crankshaft Pos Sensor !
There's also a $200 unit that doesnt even look remotely like the CKPS on my car.

 

Oops. I failed to mention. I did run up to the grocery about 3 or so miles away.
Got to the store, picked up a few items, got in the car and drove back.

About 8 houses away from home, the engine died ... I coast to about 4 houses away and park. Plug in the reader and once a again, it registers a P0727. I let her sit for 5 minutes, clear the code, and she starts up.

So, looks like I need to take a chance that the CKPS is at fault and buy another.

 

It is not without precedent for a electric coil to change characteristics with temperature. If you really wanted to prove that is what it is, I suppose you could do what we do on electronic circuit parts and alternate the heat gun with some cooling spray.