Jaguar x300 cuts out at junctions but runs fine when normal driving along the road. Also hesitates a bit when setting off again. Regards, Robert.

 

Has the fuel filter been changed?

Are there any DTCs stored? Is the MIL on?

 

Yes fuel filter changed, have not checked with diagnostics yet as no lights on dashboard. Only happens when engine warm.

 

Check fuel pressure when warm. May be a failing fuel pump.

Check all engine compartment loom connections and earth points for looseness or corrosion.

 

Funny thing, I change the fuel pump not so long back, but recently I have heard like a rumble coming from the tank, could be that the pump has slightly moved off its mounting. If it has would that cause me problems. Robert.

 

Welcome back Robert,

I've moved your question from UK & Eire Region to X300 forum. Technical questions should be posted in the relevant model forum.

Graham

 

No fault codes, but did notice one thing that happens, when i press the throttle gently and let my foot off again the engine revs quite high then drops back down to normal tick over speed.

 

Have you ever cleaned the throttle body, egr and Idle air control valve.

If not I am sure they are gunked up and the car will idle and come off idle much better once done. Some Berrymans B12 and an hour will have it done.

If your throttle "sticks" as you try to operate it by hand you need to clean the throttle body.

I did not have to reset idle adaptation after a good cleaning but also didn't disassemble beyond what I needed to to gain access. Pulled the throttle body and IACV as a unit. Pulled the EGR as a unit. (YOU WILL LIKELY NEED A GASKET IF YOU PULL THE EGR)

 

As a least intrusive thing with the cut out symptom , try a fuel injector cleaner in the fuel tank

did notice one thing that happens, when i press the throttle gently and let my foot off again the engine revs quite high then drops back down to normal tick over speed.

On the overspeed idle there is a TSB on the throttle return spring and without doing the spring replacement you can preload the existing spring higher in someones trick he documented ( I will have to find ) . See page 11 of the first document below .

The throttle body may be getting gummed up inside and binding but that involves removing the throttle body to clean it

 

Wow, thanks guys, lots to check there, will work my way through them and let you know what I have found. Robert.

 

page 11 is of the first document

 

On my ‘92 XJ40 I used to have the same sort of problem. Intermittent stall at lights, I could tell it was going to happed about a milli second before it did, a slight hiccup, push the accel and engine died.
Turned out it was the CPS, the shield wire was shorting out the signal wire intermittently, I think it was the slight change in attitude of the engine just prior to taking off. I would quickly select park fire up and away again as if nothing had happened. Of course it invariable did it when I was first in line

 

I managed to adjust the tick over speed which stops it stalling at the junctions, but when i press the throttle to go it spits a couple of times then its off like a rocket.

 

Not sure whats causing the stalling issue, but the hesitation issue is likely the MAF is gone. I cleaned mine and it didn't do jack, new one from worldcarparts fixed it. To confirm try revving car under the hood, get a sense of the hesitation/stumbling, then unplug your MAF (Car should be up to temp) and see if the hesitation has dissipated.

Check out my video of the old Maf, see the last revving up, and if you look closely after you hear me depress the throttle, the revs actually drop initially before it finally revs.

 

I think I have narrowed it down to either the TPS or the ISCV. Which one is it most likely to be. Regards, Robert.

 

Have you cleaned the TB and the Idle Air Control Valve yet?

 

Decided to clean the ISCV as recommended, I started undoing one of the little bolts and then it snapped off inside the throttle body, "HELP".

 

Well that is no fun. Not hard to fix though. You will need to drill out the broken bolt. And use a bolt extractor to remove the stub or drill out completely and Install a helicoil or a timesert.

Any salvage yards nearby.? There are 2 in the yard near me.