I posted this on the XJ8 forum and didn't get a response, so I thought I would try here.

Hi all, I have a 2004 VDP that has about 54000 miles on it. I have had it since 2006, with 6500 miles, and love the car. One problem that has been driving me crazy, however, is that whenever the outside temperature is below 25 degrees fahrenheit, the car will crank and crank, but will not start. This has been happening for two winters and I have had the car towed at least four times to the dealer and independent garages and by the time they get to look at it, the temperature has warmed up and the car starts right up. This past week, when it was 16, 18 and 25 degrees, the car wouldn't start. Yesterday, when it was 36, it started right up. Does anyone have any ideas or has anyone else had this problem? thanks. John

 

Sheesh! That makes me nervous. I just bought an S-type and found out the block heater was pooched. Up here in Canada, the winters can get cold and mine had a hard time starting the other day. I'm hoping the new block heater makes a world of difference. Sorry I don't have an answer but I'm feeling your pain!

Cheers!
Rob

 

Nobody else has had this problem? Won't start again today as it is 14 degrees F. Thanks. John

 

I've only had my S-Type a few months now but out west in BC we had a few cold snaps down to those temperatures and indeed my 4.2 was reluctant to start. I found more success with shorter bursts of cranking. Cranked for 5 seconds and then key off and on again wait a few seconds with key on before cranking another 5 seconds. Usually started after a few attempts this way but never left me stranded. I think it's important to let the electric fuel pump prime the lines with key on but no cranking for a few seconds. Goes without saying that 50 cents worth of methyl hydrate in the gas tank is a good investment in cold temperatures as well. Doesn't take much water in a gas tank to freeze up a gas line.

 

I would suspect that you have a battery thats too weak when cold. The battery is capable of cranking the car, but if cranking voltage drops in the 10-11 volt range(I dont remember the exact voltage) the ecu will not fire the injectors. Its not uncommon in colder climates for this to happen. Fully charged batteries are big problems on tadays Jaguars that have over 30 ecu's/modules to provide all those features we have grown used to having. Just think about how your laptop start functioning when the battery gets low.
EDIT another tid bit to pass along on here. the car wont start either if over a certain voltage, it does the same thing. I am occasionally reminded of this when I have a booster on a car and go to start it and it wont start(crank no start). turn off booster and starts right up...So for ya'll that have jump box/chargers in your garage this is something to be aware of

 

That's a very good point. I'm new to Jags but not new to trunk mounted batteries like my S-Type. Gives more room in the engine compartment but the voltage drop across the long cables leading from the trunk mean you need a top condition battery for everything to work well. Might try a new battery myself. Cheaper than a tow.

 

Not to hijack but my S type starts very well at any temp with no block heater. Cranks 3-4 secs and off it goes even in -30C.

 

The car started this afternoon, but I replaced the battery anyway. Will report back tomorrow as it's supposed to be real cold again tonight. Thanks for the tips. John

 

Good morning gents. After replacing the battery yesterday afternoon, I am still experiencing the no start condition this morning. It is 7 degreed F here and the car just cranks and cranks. Any other ideas? Can someone tell me where the fuel pump and relay are on this car so I can listen to see if it is running? Thanks. John

 

Fuel pump is in the tank, in the trunk.

 

The fuel pump sounds like it is running, yet no start. I was thinking maybe a crank or cam position sensor? Any thoughts? Thanks. John

 

My mechanic kept the car for about a week and tried to start it at various times during the day when the temperature was very cold. The car finally started and he immediately hooked up his diagnostic tool and the car had a code showing a malfunctioning inertia switch. He ordered the new switch, replaced it and so far, so good. I'm thinking the cold weather caused some part of the inertia switch to shrink and not make contact where it should and as it warmed up, the part expanded and made contact.

 

wow, inertia switch... that's a new one for a no-start.

Please keep us updated linklaw if it remains a continuous fix for you. It never hurts to have more potential sources for this very vague condition. We thank you in advance.

 

Well, apparently the intertia switch was not the cause of my problem. Last week, with the temperature at around 7 degrees F, the car started on two consecutive mornings. I thought I was home free. Unfortunately, the third real cold day the car would not start. It was parked at my office and for three days straight it would not start, even with the temperature at or around freezing. I finally had it towed to the repair shop the day before yesterday and lo and behold, it started yesterday. I stopped by this morning and it fired right up. This problem is really starting to become an aggravation as I never know whether the car is going to start when I'm going to work. Any ideas? Thanks. John

 

There has been a significant number of post on failure to start this very cold Winter. I have been watching but have detected no specific issue that stands out.

 

You are not alone. I have the same problem with our x-type. Once it hits -20C, forget it. Car has new battery, posts are tight, premium fuel, gasline antifreeze added, inertia switch checked, full synthetic oil in crankcase, plugged into block heater, it doesn't fire at all, but cranks over easily. It warmed up during the day to -10 and it turned over in about 4 seconds. Runs great otherwise, and doesn't seem to starve for fuel. No warning lights or codes show at all.

I'm stumped too.

 

I've often thought mounting the battery in the boot/trunk wasn't a good idea because of the long lead to the starter motor, but even Rolls-Royce do it! It might be possible to fit another long battery lead on top of the existing one if the screws are long enough to take it.
When you come to starting on a very cold morning, try chucking a couple of thimble-fulls of petrol inside the air pipe to the throttle body first, and then see. If it bursts into life immediately, you know where your problem is. Costs nothing to try. In the old carburettor days, if the carb. had an accelerator pump, you just pumped the pedal a few times before starting in v. cold weather.
Leedsman.

 

Just remembered another dodge for cold starting: Pour some boiling water on the inlet manifold...
Leedsman.

 

I remember the Jaguar Workshop Manual for an old XJ6 I once had stated that the fuel injection system had two halves which came together at the fuel injectors, (1) the fuel supply at a defined pressure, and (2) the fuel demand, in the form of a variable injector pulse calculated from the sensors around the engine. The manual stated that the main influence on the pulse was provided by the engine temperature, and the air mass flow, all the rest was just trimming. Clearly at engine start, there is not much air mass flow, but the ECU detects engine start and follows an enrichment process to get the engine going following which it is turned off. On the old Jaguar XK straight six there was also a cold start injector, but this is probably no longer used, and the system relies on wide injector pulses.

Now I don't know the detail of the XJ Series fuel injection system, it will surely be similar to the previous V8s and there should be a fault-finding procedure to follow for start failures. I don't see how the ignition system can be susceptible to low temperatures, it should work OK, implying you have a fuelling problem.

I assume it starts OK when the weather is warmer ? I had similar problem with my Rover 75 V6 after a very cold weekend standing 2 nights (-10c overnight), and a new battery cured it, but not your car so clearly there is something else not quite right. You could try getting the fuel pressure checked out, there should be a take-off for a gauge on the fuel rail somewhere, (this is normally a workshop job). There is also usually a fuel pressure regulator somewhere; if this is stuck open you will have no fuel pressure. Take a plug out and see if it is wet with fuel.

There - that's my knowledge exhausted !!

 

I used to have an old Saab that would sometime act up like this. We never did find a "cure", but this helped: By turning the key on and then off (without engaging the starter) a few times, a little extra fuel would get injected before the first actual attempt at turning the engine over. This seemed to help!