I have a really annoying problem with my car at the moment.
When it is at running temperature it sometimes stalls as im coming to complete stop.
It has never stalled when it is "cold".

And about 50% of the time i try to start the car it seam to be completly dead, no attempt to fire, so i release key and try a second time and it fire straight up as nothing was wrong.

The car runs perfect at highway and at Idle.
But as I'm stopping it just suddenly die without a warning.

I recently changed sparkplugs (Denso iridium or something like that from britishparts.co.uk) they are the ones for the early 3.2 engine.
I also changed the thermostathousing for the aluminium one as the original plastic one had a crack and was leaking.
Then I also had to take of the TB and intake for access to the rear bolts on the thermostathousing.
As I was doing this I found 1 loose vacuum hose (not sure what it is for, seems to go through the firewall), It was hooked back in place.

This stalling problem is making my crazy.. Any suggestions?

 

Initially I was thinking MAF, clean it and let us know the results. Then as I read more I began to suspect a vacuum leak and you mentioned the one you reconnected. I would do both, clean MAF and start checking for a vacuum leak. That hose you found may be so loose its allowing air around it and causing your issue.

 

I would do as suggested and clean the MAF. Right after that I would perform a hard reset and see if that helps. Have you checked your air intake pipe for any cracks on the underside??

 

Hey Addicted, do you think his vacuum line to his brakes from the back of the throttle body may be cracked or that O-ring dried/cracked? Thus when he brakes to decelerate it causes this issue.

 

I would agree with that. I was starting with the simple checks first before going to the more difficult checks. I see it like an electrical issue... Checking the fuse first before chasing a shorted wire.

 

Cleaned the MAF, as good as possible, as this is the closed version where you cant take it apart. No change in behaviour.
Double checked all vacumlines, all seem fine, even did a check spraying starting gas at all suspected places, no reving, for fun tried to disconnect a vacuumline and spray at it and engine revved as predicted.

Im leaning toward a ignition related fault.
Maybe spark gap, or bad coil(s). Car runs very nice at normal idle, better than what it did before spark plug change, and when driving, it only seem to stall when it get load at idle. It hessitates when i shift gears and when fans come on, but only stalls completely right when the car is about to be standstill.

 

Ok, so far so good Britax, ....do you know what your fuel pressure is? Could be something as simple as a clogged fuel filter.
What is your plug gap btw? ....I do believe they should be .9-1.0mm or .35-.39

 

I have a 6month old fuel pump and filter, it quit working last autumn. I have not checked fuelpressure, but it worked fine before i changed sparkplugs.
I didnt measure gap, as they where supposed to be the correct plugs for this engine I foolish didnt measure..

This morning I had a 75km trip to my workplace, a trip i do 1-2days a week, and the car is definitely lacking power at low revs.
This route has quite a lot of smaller hills, and using cruise control the car downshifts atleast twice as often as it used to and it is using aprox 15% more fuel than usual.

I'm changing timing chains and tensioners this weekend anyway, so will check the Spark plug gaps at the same time.
Car has driven 210.000km and Iam not sure if it have the new tensioners, most likely the 2.gen, as I see the engine had a dealer programming autumn 2000. Later years the car has not been at Jaguar dealer for services.

 

I'm actually starting to think it could be the fuel pressure regulator.
As I came to realize the loose vacumline was connected to the T between the fuel pressure regulator and TB, meaning it did not receive any vacuum previously.
It could cause a lack of pressure under high vacuum conditions as startup, idle and cruise.

 

Ok, so I took off the vacuum line from the fuel pressure regulator, the car is still a bit hard to start, but i remember it used to be hard to start occasionally before i changed filter and fuelpump too.
But it does not stall at stopping, warmed up the engine and did a 15min town driving with many stop and go and it didnt even hessitate a single time.
Rock solid 600rpm at standstill and 800rpm right before stopping.

So most likely a bad fuel pressure regulator at least, but will try to get my hands on a fuel pressure tester to comfirm low fuel pressure.

 

Keep us posted, also an fyi...overly gapped plugs will cause sluggish operation and use excessive fuel. Generally said, a tighter proper gap is for performance, a wider proper gap for efficiency. Anything out of those two tolerances will create engine function issues.

 

I'll keep you updated.
This FPR is really expencive... $230..... wow

 

Got my new FPR a couple of days ago and the car has not had any stalls with the vacuum pipe connected! So that seems to be sorted out!

But it is still hard to start sometimes.
Does not seem to matter if engine is hot or cold.
I have to crank the car 3 times, and seem to almost always start on the 3rd attempt.
If i try to crank continuously it seem to fire one or two cylinders now and then after 10sec, but does not start.
When it starts on the 3rd attempt it starts immediately, just like nothing is wrong.

Once it started but seemed to only fire on 4 cylinders or something like that, really rough and pressing the accelerator it slowly increased revs, but it didnt fire on many cylinders.
Stopping the enginge and starting it again, it started perfectly..

I have not had any issues what so ever during driving.

 

A starting problem like you describe could be a fuel pump problem. Every time you turn the key the pump runs briefly, so if it's on the way out those three tries might be required to build pressure.

Try turning the key on then off a few times before engaging the starter.

 

I agree with RJ237, turn the key without starting the car a couple times then all the way to start it. This is a procedure you use when you run out of gas before trying to restart it so as not to burn up the pump(s) (basically priming them). But in this case your trying to build pressure prior to actually starting it to get a better idea of what RJ237 is suspect of, ...a possible bad pump or perhaps a bleeding line.

 

Got a fuel pressure tester connected today, and pressure seem to be perfect.
As i turn the key it goes straight up to 3bar immediately, and stay there. When car starts it is lowered to aprox 2.5bar as it should.

Cant really say if turning the key 3 times before starting helps.. sometimes it seem to work, sometimes not..
I'm leaning towards an ignition fault..

 

What were your findings on the plug gap? After rereading the posts, I'm a little miffed at this situation. If definitely seems like a short or loose connection at some point, with the intermittent issue.
I know this is for the AJ26, but it can't hurt to review this TSB....http://www.jagrepair.com/images/TSB/...Flowcharts.pdf
Here's one on an ECM reflash, check your VIN....http://www.jagrepair.com/images/TSB/...rogramming.pdf
The V6 starts on Pg 165 of 264...http://www.jagrepair.com/images/Trai...ual-9-5-01.pdf

 

I have been thinking of short or loose connection.. but it does not hesitate at all after start, only issue is starting..

I have not had time to do the timingchain or check the sparkplugs again.
They should be 1.1mm according to manufacturer (Denso).

 

Connected a cheap OBDII reader and upgraded to Torque Pro on my phone and now I'm pulling 2 fault codes..

P0340 - Camshaft Position Sensor "A" Circuit(Bank 1)
P1336 - Powertrain (guess this is the Crankshaft position sensor)

But the car started right up today, tried 3 times an no hard starts..
So guess it is an intermittent issue.

 

Looking at where the camshaft position sensor is located, got me wondering if there was a wire issue, so tracking down the sensor I found it to be a loose connector!
Probably didn't push it properly together when I removed the trottlebody when I replaced the thermostathousing.

So cleared the codes, and they did not return.
Car seem to start up fine now!

Loose connector + bad fuel pressure regulator was the source of my issues!