Hi all, Recently my jag has been cranking quite a bit before firing. Occasionally I've had to put my foot to the floor before it would fire, leading me to believe that for some reason it's been flooding?
I've just used a Scan tool that has reported code P0116 ECT Sensor Circuit Range. Great I thought, that's an easy fix, I'll just change the sensor, I vaguely recall doing this before. After looking through my records, however, I discovered that I have fitted a new sensor in Sep 2017, July 2018 and Sep 2019.
My question basically is are coolant temperature sensors supposed to be a consumable? I mean replacing one every year or so seems a little excessive. has anyone else had this issue?

 

Not intended as a consumable by Jaguar, but some aftermarket suppliers seem to think they are!. Some very poor quality items around, as I have experienced.

 

Yeah, they don't go out often. But the prices range from $20 to $2. Did you manage to record what brand, or where you got it from?

 

The ECT sensor triggers after warm up the engine regulation to go into closed loop mode which brings a intentionally rich fuel mixture back to a more lean mixture , Short Term Fuel Trim . In the cold starting sequence your engine regulation should be in the open loop mode .

You may have a hidden issue with your Camshaft Position Sensor ( code P0340 ) that is used in the starting sequence only and not related to cold coolant temperature or open / closed loop regulation mixture

The Cam Position sensor has targets in the form of 6 different width gaps around a 360 degree circle

This way the Cam position sensor knows exactly which of the 6 cylinders is on firing top dead center

The Crankshaft Position sensor only knows when the # 1 cylinder is on top dead firing position or top dead exhaust stroke in a 4 cycle engine

The ECU must learn which of the 2 rotations of the crankshaft is the true top dead center firing

The engine will eventually start with the Cam Position Sensor connector removed but there is a 50 / 50 chance it was trying to fire on the # 1 cylinder top dead center exhaust stroke .

In seeing the engine not starting the ECU will revert to the second coming around of the Crankshaft Position Sensor as the true # 1 cylinder top dead center firing and the other cylinder firings are slaved to this reference point and you get a successful start up

Putting the pedal to the floor allows the ECU to purposely by design from my understanding stop fueling the cylinders so the oil under the piston can reestablish cylinder compression lost from unburnt fuel from failed starting attempts

Bore wash condition

There is a adjustment to the Cam Position sensor relative to the fixed Crankshaft position sensor top dead # 1 cylinder location other then the gap in the missing tooth method as you need to use the marks in the engine block when using the andy bracket




The voltage sag during engine start on this engine should not go below 11.4 volts or the ECU will not properly be powered stopping the fuel injectors from pulsing and a no start but plenty of starter rotation

 

I've purchased them all, online from a local Jaguar parts supplier Jagdaim in Morrabin Melbourne. looking back at the orders, they are all (unbranded) or just the item number is mentioned (LHE1600AA) and the price ranges from $12 AUD to $30 including postage.
I think you may have hit upon my problem Vee. I'm possibly repeatably purchasing poor quality aftermarket items as mentioned by Countryjag. To be honest I always just assumed they were a cheap generic sensor so never really put any thoughts into it. I may have to do some research on their origin.

 

Thank you Parker, that info is fantastic. I've been doing some reading on "bore/cylinder" wash as I wasn't familiar with the term. It actually really fits the symptoms and the sound of the engine while it's cranking with no start. Cranks really fast and sounds like there is a loss of compression. I also have Andys Bracket.
I Understood everything you have written but is there any chance you can expand on that last (There is an adjustment to the Cam Position sensor relative to the fixed Crankshaft position sensor top dead # 1 cylinder location other than the gap in the missing tooth method as you need to use the marks in the engine block when using the andy bracket) Cheers

 

The bore wash condition you may have put your engine into is a consideration in squaring up the starting sequence and good that you can discern if it goes in or out of that condition

Once the starting sequence is squared away and you're not having unburnt fuel washing the cylinders you will not have to be concerned with the condition as the engine comes to rest after a engine run

There is a method of removing the plugs and adding a bit of penetrating oil on top of the cylinders ( rislone or gun oil ), the car will smoke until the excess oil burnt off . But that's in a excessive condition that holding the pedal to the floor does not correct

The bore wash condition is more relevant with the 98 / 99 newly designed V8 that did not have the steel sleeves in the aluminum block cylinder bores but the inline 6 ( AJ16 ) does

The sulfur in the fuel would eat away the metal seal between the piston rings and the cylinder walls so that combined with the fuel washing the cylinders made fore a almost impossible combination to start the engine

This was later resolved by removing the V8 engine ( AJ26 ) and replacing with one that later had steel sleeves ( AJ27 )

Off the top of my head there is a timing arrow attached to the block at about 5 o'clock and marks on the toothed gear

The picture shows the andy bracket and not aligned with the missing tooth gap and the painted white marks are for a different harmonic balancer slippage issue

The timing mark on the block corresponds with the missing tooth gap on the crankshaft position sensor target if using that method of determining TDC of the # 1 if you have the factory sensor bracket

If you have the elongated andy bracket you must use the engine block marks or the true mechanical timing will be off by 5 degrees as the ECU must have a mechanical reference point

Mechanical timing of the machine parts being different then the variable ignition timing the ECU modifies during high engine load or power demand of the driver ( advancing from say 15 to 20 degrees before TDC )

Sometimes the timing is electronically retarded ( from say 15 to 0 degrees before TDC ) again by the ECU during the engine start sequence for better start performance

The Cam rotates 1 revolution for every 2 on the crankshaft and it's mechanical timing is aligning the stamped circle in the plastic window on the camshaft sensor as it comes around with the true TDC of the # 1 cylinder as you have that lined up

Without having messed with the timing chain you can do this looking at the outside of the engine but there is a way to look at your valve sequencing to know where you are at with the # 1 cylinder piston either TDC ignition or TDC exhaust stroke but that's not your case

There is a factory technical white up in how to adjust the cam position sensor but it's writing is about as coherent as my writings

The way your engine coolant temp sensor effects your starting sequence is if working correctly should be a rich fuel mixture with a cold engine before the coolant warms up , this would aid in a cylinder firing off but work against you in bore wash , so we are looking at balancing the factors

At the point of time of a failed sensor ( seeing warm when should see cold ) making a more lean fuel mixture making it harder for a light off

Have you checked the condition of the ECU connector and specifically the coolant temp sensor sockets for corrosion or missing pinching socket finger halves ?

Your sockets are Red 14 and Red 31

 

I've just received the replacement sensor (LHE16000AA), It is branded "Elwood Sensors ES120-4" if anyone is interested. I'm not sure of its quality or OEM status.