2.7 TDVi reluctant to start when warm

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PaulGover
Posts: 403
Joined: Mon Jul 19, 2010 8:06 pm

2.7 TDVi reluctant to start when warm

Postby PaulGover » Fri Nov 23, 2018 1:14 pm

The subject line says it all. The car is a 2008-plate facelift X350, with just over 100,000 miles on the clock. Used mainly for driving on motorways, so DPF and its friends are all happy.

Usually, it starts on the switch, no problem. Not even if I switch off at red traffic lights. But if it's left for an hour or two, sometimes it just spins without firing. I've waited for the glow plug light to go out, of course.

Of itself, it's not a big problem, two or three tries and it fires. But it's happening a bit more frequently, and if it's an indication of a progressing fault, I'd rather sort it before I'm stuck in a car park miles from home/garage.

I've a Foxwell ODB scanner - nothing logged. Battery is a Bosch or Varta (forget which) replaced a couple of years ago.

Any thoughts please? I may just have to wait until it's become more repeatable - no point taking it to a dealers if it won't fail on command!
1981 XJ6 Series III basket case
1991 XJS V12 "facelift"
2008 XJ TDVi

PaulGover
Posts: 403
Joined: Mon Jul 19, 2010 8:06 pm

Re: 2.7 TDVi reluctant to start when warm

Postby PaulGover » Tue Nov 27, 2018 11:10 pm

I'll propose my own answer. According to the workshop manual, the glow plugs aren't switched on if the engine is sufficiently warm. At a guess, they're off, and the weather's cold enough to prefer otherwise. Probably some tweaks to the relevant ECU would fix it, but whether Jaguar's diagnostic/control thingy has any settings to change it is doubtful. I may ask my local dealer if he knows.

Out of interest it also says the plugs take 18A each - that's 108A in total; leaves a bit less for the starter then!
1981 XJ6 Series III basket case
1991 XJS V12 "facelift"
2008 XJ TDVi

ptjs1
Posts: 2526
Joined: Thu Apr 27, 2006 7:14 pm
Location: Kent

Re: 2.7 TDVi reluctant to start when warm

Postby ptjs1 » Sat Dec 01, 2018 8:38 pm

Paul,

You may well be right although I would have expected closer to 5a - 15a max on a glowplug. Even so that's still 90a, which is why owners should always wait until the light has extinguished before asking for the current draw on the starter.

Sadly, most drivers are quite impatient and just turn the key to start straight away from cold!

Good luck with your continued investigations!

Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)

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J44EAG
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Location: Warlingham Surrey/Faversham Kent

Re: 2.7 TDVi reluctant to start when warm

Postby J44EAG » Sat Dec 01, 2018 9:08 pm

I offer this idea.

Certainly on all MY2000> Jags that I`e owned over the years, although not diesel models, the cylinder head temperature sensor near the thermostat housing, is prone to failure after about 80K miles. Its internals can break down, give odd dash temperature gauge readings and more importantly, ruin cold and half hot starting abilities. This failure impacts on mixture control via the Power Train Control module. Partial failure of the sensor has lead to cold start problems with total failure preventing the car from starting at all. Sometimes a semi duff sensor does not show up as an issue even when the car has been electronically diagnosed.

The sensors...fit genuine units only and ignore after-market products. Only a genuine part guarantees that the resistance spec is truly correct. Certainly for petrol models, the sensor costs around £26. You will no doubt find a genuine part listed on the internet from a genuine parts supplier or buy from a Main Dealer. If you have a JEC club membership card, you should get a 20% reduction.

If I owned your car, this would be the first part I would replace and take that unit out of the equation. Having replaced the sensor and the car returns to reliable operation, you have found the problem. If not, then you will have to look further.

Hope that helps.

Mike K
X350 Co-ordinator

2004 XJR

PaulGover
Posts: 403
Joined: Mon Jul 19, 2010 8:06 pm

Re: 2.7 TDVi reluctant to start when warm

Postby PaulGover » Tue Dec 04, 2018 12:08 am

Mike, that looks worth following up, thanks.
1981 XJ6 Series III basket case
1991 XJS V12 "facelift"
2008 XJ TDVi


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