Can anyone help with this???

Car (4.0 soverign, 1995) has had starting issue and running lumpy. It turned out to be coil pack had failed causing a misfire.
Garage fitted new one and all is well... when it's running!

But getting it started from cold is bad. The longer it sits after running, the longer it takes to start.
If you run it, switch it off and start her again a few minutes later, then no problem. But the longer you leave her, the longer it takes. Turning and turning until it fires up. Wife just called to say after she left it sitting for 3 hours it took 7 attempts to start up. But ran fine once it started.

Any ideas anyone....??

 

You could be losing pressure in the fuel rail as the car sits. Next time it's cold, try key-on key-off a few times before trying to start it (i.e. turn ignition on, wait a few seconds, turn ignition off - repeat).

Turning the ignition on should run the fuel pump for a second or so - listen for a whirring noise from the back. This is to prime the rail. If you have lost a lot of pressure a short burst may not be enough to get the required pressure.

Other possibility is the Cam Sensor but that should be a constant issue, rather than varying by time.

 

Hi flying scotsman,

b1mcp's suggestion is a good way to identify problems with the Fuel Pressure Regulator (FPR), which is mounted at the forward end of the fuel rail, and/or the fuel check valve, which is mounted in the fuel tank. These two components work together to maintain fuel pressure in the system, but over time, one or both of them lose its ability to hold pressure, so as the car sits the pressure leaks down. The fuel pump must then run longer to build up enough pressure to atomize the fuel through the injectors. I don't know of a practical way to isolate this problem to either the FPR or check valve, so it may be worth replacing your FPR to see if things improve. The photos at the link below show how this is done on our '93 XJ40, which is very similar to an X300 (the FPR is the same part).

http://www.jag-lovers.org/snaps/snap...?id=1366662355


There are a number of other possible causes of slow starting, and in my experience it's often a combination of multiple issues. But considering that your engine wills start right up when it's warm, one possible suspect is the Engine Coolant Temperature Sensor (ECTS), which is mounted on the top of the thermostat housing. The ECTS resistance varies with temperature and its signal tells the Engine Control Module (ECM) to apply cold-start fuel enrichment when the engine is cold. If your ECTS is failing or there is a problem with its electrical connector or harness, the ECM may not know when it needs to enrich the mixture for cold starts. This can be aggravated by intake air leaks or vacuum leaks, which further weaken the mix. You can test the resistance across the terminals of the ECTS with an ohmmeter when the engine is cold and hot and compare the readings with the specs in the manual.

Another possible aggravating issue is battery voltage. If the voltage sags much below 11V while cranking, the ECM will not trigger the ignition to fire. Since the engine is more difficult to crank when the oil is cold, perhaps the voltage is sagging initially before climbing back to the point the ECM will fire the ignition? If you have a fast-reacting voltmeter you can check the voltage across the battery terminals while cranking the cold engine.

Please keep us informed.

Cheers,

Don

 

Hi folks. Thanks for your help.
I went back out after I got home from work. It had sat for nearly 3 hours so was effectively cold.

Tried switching ignition on and off 5 times and letting it sit for 20 seconds each time incase system was low on pressure.
It cranked and cranked with nothing happening.

So tapped and jiggled the relays in the boot with no joy. Tried reseating them also with no luck.

I have no pressure valve under the bonnet so couldn't check fuel pressure. But could also find no obvious leaks.

Tried squirting some flammable fluid up the air intake with no luck.

During whole process could hear no noise from the fuel pump, so either it wasn't working or no power, or the system was pressurised.

Then gave it one more go (while being heartily impressed with the battery still spinning it over quite fast!) and noticed the rev counter wasn't moving!

So , having replaced crank sensor twice now, I'm convinced the sensor has gone again.
Question is....
don't these things just die? I didn't think they died slowly? Can they gradually die? ... confused!

 

Glad you figured it out!

There are plenty of reports from owners that seem to indicate that one failure mode of the CKPS is intermittent operation for a surprisingly long period of time.

It might also be worth checking for any accumulated gunk between the sensor and the crankshaft toothed reluctor ring. Also check for looseness, corrosion or backed-out pins on the sensor and harness electrical connector, which might make some sense if the pins were making a better connection when warm than cold.

Please keep us informed!

Don

 

Hi Don.
I will post back when I change it and see what happens. I'm just going by previous experience. The last 2 just died. However, thinking back, the 1st one would just shut down when driving. Like I had switched the car off and then just 'catch' again.
This only lasted few days then one day it wouldn't start, so.. hoping this is all that's wrong with her.
I love this car, (second Jag after an S Type) and love driving her...but she is slowly trying my patience with lots of niggly faults.

 

Also, have a look at the actual connestor for the Crank Angle Sensor.

The connestor is for 4 wires, but 2 ports are only used, so 2 ports are open, and since its mounted vertical, crud/water/muck, seaps into that connector, making electrickery mystery.

Mine did this after a heavy rain and high speed, and after some time if actually dried out eventually and the car was fine.

I took the time to seal the unused ports with RTV, and never an issue since.

The snaps show the lower portion (sensor unplugged), plus other views, but the top sealed potrtion (on the sensor pigtail) are too blurry (not a good photagrapher), but once you look carefully at it you will quickly see what I am getting at.

Mine was quite contaminated with oily mist type gunk. Quick spray with solvent, and all sweet.

 

Thanks for that Grant.
I've already given it a good dose of solvent / cleaner but that doesn't mean there isn't still some crap in there.
When I get it apart I will give it a good clean and check up.
Picked another sensor today so will hopefully fit it tonight and see what happens.

Did have a chat with a local expert (ex jaguar mechanic and fountain of knowledge) and he said the potentionometer may be knacked. He has had this before. The sensor tells the ecu the throttle is wide open so the ecu gets itself all confused and refuses to start up.
No idea how to check this though??

 

Yep,

They suffer from gravity oil flow into the innards, and that just screws their thinking.

Clean all the gunk out of the throttle body, and remove the TPS, oil filter off is the easiest, and DO NOT turn ON the ignition with the TPS unplugged. Clean it with solvent, and that takes some serious time as it is supposed to sealed, haha.

Work the potentiometer, and work it some more. It is spring loaded to idle. Using an OHM meter to get some readings from 2 wires, and I forget which 2 at the moment, and when you get a nice clean rise in ohm from idle to WOT, it is deemed as OK.

Refit it, plug it in, refit a new oil filter, see what happens. I have had success with reviving them, some have not.

The TPS is a simple bolt up, and are not adjustable as such. Bear in mind that mine is a 3.2ltr, and they may be different from a 4ltr, I dunno.

 

SHE LIVES!!

SHE RISES LIKE LAZARUS..!

Put the crank sensor on and she fired right up. Hopefully it wasn't a fluke! LOL

Anyway, will leave her over night and see how she goes in morning.
Thanks everyone for your advice, much appreciated.

p.s..why am I suddenly calling 'it' , 'her'..??

 

I have replaced 2 crank position sensors within a few thousand miles. Both genuine Lucas parts. The sensor is a very simple device and shouldn't give this trouble. I think that the next time (as I am sure there will be one) I will use an aftermarket one as they couldn't possibly be any worse than the real thing.

 

Lucas strikes again.

 

I was only using second hand items so can't confirm how old they already were.

I did notice on teh old one, just how dirty it was with road grime, oil, grease and general muck.
When I get time I'm intending to give it a good clean and re fit it to see what happens.
I'm not convinced that this has just got so dirty that it can't work properly.