Hello o' wise community! Spot of issue with mine
Just yesterday my car decided to stall on me at the lights as soon as I set off, the engine just cut out with no warning, no warning lights or any strange sounds.. just died. Took about a minute of sitting off in busy traffic to turn back on again when the ignition was turned.
Continued on my trip with the aircon off, decided to try the aircon again on and 3 minutes into the second trip, it stalled again at the lights on idle, with again no warning.

So my question is community how do I go diagnosing this issue? The key issue seems to be the aircon running but however on my third test, it seemed to work fine after doing several laps for 20 minutes with it on.
- Aircon was regassed two years ago, no complaints since yesterday
- New fuel filter in September
- No warning lights are or were present, idle and drive was normal, nothing rough or anything out of the ordinary - simply engine just cut out
- car wouldn't crank immediately - would take about a minute completely off, before starting again when cranked.
- Belts were replaced about 10 years ago

Not sure where to start? AC Compressor clutch? something fuel related? Coil packs? Let me know what your thoughts

 

The A / C does command the engine regulation to beef up under compressor load so may be on the edge there but there is an easier first try

700 ish idle RPMs ? need an accurate number

See page 90

X300 00/E COVER

The both starter motor and engine regulation ECU first power is the right engine bay fuse box relay # 9 in fuse box corner , this is your common denominator for both engine stalling and starter motor

The engine ECU only second power used at all times is a large # 5 right ECU controlled relay ( this is controlled by the ECU and brings power back into the ECU on a different wire

You can swap the # 9 right with the left engine bay fuse box # 7 relay ( left only runs the car horns )

# 5 ECU controlled relay with a headlight ( bright of dim ) or fog or A/ C clutch relay which you want to keep the same for testing

Try the small # 9 relay first as your common denominator and the large # 5 last as hard to remove

Hi Watto700 as your earlier thread on ECU power as fuse # 12 powered by closing the right engine bay fuse box relay # 9 is included as the blue lines middle wiring pic

In each fuse boxes fuse # 10 , 12 , 14 , and 16 require the relay in the corner of all fuse boxes to close , the remaining fuse are hot at all time direct to battery

There is a Jaguar TSB on the Papa Indy 1 and 61 connector corrosion between the ECU first power fuse # 12 right as pin 4 of the Papa Indy 1 connector and the ECU module in the middle wiring pic

This is the White / Pink wire in this ECU case , the starter enable probably runs through one of these 2 connectors in the lower engine bay pic

 

If you search my past threads, I had a situation where I noticed my RPMs would dip every 32 seconds. When the car was loaded up, AC, headlights, etc, the car would stall when stopped at a light. If you indeed check my posts, it took me three shops and a lot of time before a mechanic finally figured out that my intake manifold was failing and it was letting air in, causing a vacuum leak. I guess it needed to build up enough vacuum, long enough at the intake manifold to finally suck enough air in to blip the RPMs? It wasn't something that was going to be simple to spot.

I suspect you might have something similar going on. Maybe not 32 seconds, but perhaps you can keep your eye on the RPM needle when idling, with the engine hot. Keep the car in Drive, with your foot on the brake and the AC off. Watch the RPM needle and see if you can see it dip on occasion? Maybe keep an eye on the voltmeter too? One of the two should indicate something. If not, then start loading the car up, maybe start with headlights and work your way up to AC?

Keep in mind that I did the cigar smoke test, took it to a neighborhood shop that does a lot of good work, and then took it to one Jaguar Specialist before I went to another Jaguar Specialist that solved my problem. I would certainly test your system with the cigar first, just to make sure its not an easy leak to fix yourself. After that, you might have to consider a higher authority. The problem is that, for me, it fooled two other shops....

 

Keep in mind the paper change in RPMs in park reference page 80 so not 700 ish

You can use tape on the RPM gauge to watch easier

You can cap the intake manifold ports at the fitting for the fuel pressure regulator top vacuum hose , the under the manifold about cylinder 2 or 3 port for the EVAP system , and the banjo fitting ( power brake booster ) on top of the intake valve with common children's moding clay at the dollar stores ( there are more professional temporary seal leak clay types but not necessary for a temporary test

The banjo fitting is kind of weird to remove the 90 degree fitting as it needs to come off the banjo fitting

The brakes will be unusable

 

Hi all
Subsequential testing as follows - today
Idle with lights off and aircon off - 800RPM in Park, 700RPM in drive with foot on brake
Same results with aircon and lights on

On the day of incident, it was notable hot weather and the voltage meter was sitting just above 13 in drive and idle before cut off, and afterward

Today, voltage meter was reading a healthy 14.5 on the gauge aircon and parkers on while driving and idle for a trip.
No visible leaks seen in engine bay as of late, everything seemed to be in place, no frayed wiring either (or at least none I could see)

Only theory could maybe sitting at 13v on a hot day with the aircon and parkers on made it crack? Still not sure today was fine, possible once in a blue moon hiccup? I was under the impression above 13v driving was normal

 

The alternator output voltage of 13.5 to 14.5 good at the alternator B + post , the gauge reading is very accurate so must be picked up / test point at the alternator small mires connector

The battery at full charge will be in theory 12.75 but can be overshoot by the higher alternator charge and then as an exersize , if purposely cutting off alternator may read between 13.0 and 12.75 until battery comes to electrical equilbrium ( plate charge concentration near plates ) or battery draw which ever comes first

The engine should not stall until battery drained over driving to a low state of 11.4 volts

The idles are a tiny bit high and at least not low on the edge of stalling so I would forget it

So I would say unstable voltage regulator inside alternator ( part # IN435 ) , is the voltage the same on changing engine RPMs

You can use a peice of tape on the gauge to keep easier track of values in traffic

There is some battery cable terminal post connections betwenn the battery and the alternator

Right at the starter solinoid 2 cables tie point

On the right wheel well shell

2 on the engine firewall

The fuse box big cable terminal post

Under the rear seat pan as the mega fuses ( hard to get to as rear seat pan removal )

and mega fuses right at the turn down at the battery positive post

 

bad track in the TPS causes most of those weird off idle stalls. iac steppers also fail sometimes

 

Yes, the TPS has been known to cause strange problems, even when successfully bench tested. It just sucks that it is such a pricey part.

 

This has to do with the sensors using pure DC power and the stray AC voltage from subpar Ignition coils induced AC stray into the sensor wires , nothing is perfect , but you can beat it

Something for free is the engine ground strap on the inboard starter mount bolts

Best got from under car with 13 mm socket on a 3 or 6 inch extension

The strap on the frame can get comprised and cleaned with a wire brush on both the strap and car , preserve with light bulb grease in the small packets at the local auto parts store counter

The engine ECU has an external ground strap at the lower ECU mount bolt

There are other grounds in the engine compartment top side including the 2 small ground studs below the large battery cable power studs , 2 small as 3 or 4 wires on the chassis rail maybe 12 inches aft of headlights

This is a housekeeping task to bring things up to snuff and maybe resolve your issues for free

 

Hi all
Continuing to update on progress, the car was completely normal for about 5 days, however just yesterday being a fairly hot sunny Australian day, strife occurred.

The car proceeded to stall again on five occasions on my trip and even shut itself off more irregularly than the last, with the aircon off and stalling at low speed and idle. Later in the same trip, I experienced the car jittering and jerking (like the engine was cutting in and out rapidly in quick succession) also briefly. Voltage was sitting at 13.5, and again no warning lights and no stored codes as of now

Spoke to two of my local Jaguar specialists, and one suggested that the crank sensor distance (between the sensor and the crank and the hot weather affecting it all), and the other suggested replacing the engine/cam management system, so far have just swapped out my aftermarket crank sensor with a cleaned up, original sensor (working fine as of 6/03/25)

Also for Parker: Voltage is normal under different RPM's, and still no abnormality with any (double checking RPM with a live code reader, 700 in idle, 600 in drive)
For Vee: Had the car also checked by my general mechanic for vacuum leaks, and he found nothing, the voltage when these stalls occurred as mentioned above. I have seen it fluctuate between 14 to 13 one time but nothing super abnormal, most likely general movement when other things such as my parkers and AC are on).

What baffles me is the car has handled hotter days than this with the AC and parkers on all summer over here in Australia.

Will wait for another hot day and report back, also going to look at all the mentioned above including any fuel lines, the IACV and TPS possibly, any coil pack wiring, etc.
With said updated symptoms, now just being stalling at idle on hot days regardless of the aircon, let me know your thoughts and thank you so far everyone for your input (the engine rapidly cutting in and out also had me concerned)

 

The 2 relays that power the ECU as small # 9 right engine bay fuse box corner relay and the large right side # 5 ECU controlled relay try ?

There are swapping options and the large one can be hard to remove , penetrating oil spray in the socket / relay joint seam

An open spot on the TPS variable resistor wiper blank should not cause a complete stall in my opinion

IAC valve

Vee has a test / reset of the IAC valve

Give the MAF connector pins / blades a very slight twist as Vee has found and by the MAF losing signal at Idle may be too critical ( the ECU will revert to not using the MAF with different non optimum full performance data maps ( limp mode in a way ? ) but takes time switching with or without )

Wild stab but a very hot day may relate to the vapor pressure high in the fuel tank / EVAP system venting properly

 

Does your Australian model have a EGR valve , your live data reader may have an EGR_ERROR parameter ID ( your X300 EGR does have a EGR arrived to position sensor and EGR gas temp sensor ) as the target value is 0 % error in all engine ranges , but I would not expect it to be perfect as it responds ( time lag )

To identify if you have one there will be 2 small solid tubes coming out from the bottom of the exhaust manifold casting pairs , but you can still peak on the top of the intake manifold between cylinder 3 and 4

 

i have shard him the iacv test process.
amongst other things.
his fuel trims appear to look good also.
and we do not have egr here.

there are 2 metal lines that come out of the exhaust manifold (atleast on my car) i have not traced the all the way back but believe them to be the auxillary air compressor.

 

The about 1 inch thin flexible line that goes into the rear of the rear exhaust manifold is I believe the secondary ( smog pump ) air but I never recall tracing it back myself

The manifolds come in different versions to have or not have these ports or maybe capped off ( production line parts shortage )

 

I have many posts about my vacuum leak, missed by two of three mechanics. The tell tale symptom seemed to be a dip in my RPMs every 32 seconds, at idle. The more loaded the car was, with headlights, AC, radio, the more noticeable the dip. On hot days, it was enough to stall out the car.

You don't need a meter, or anything, the needles on the car are a perfect analog display for this kind of troubleshooting.

 

Hi Vee,
In addition to what you mentioned, the RPM's are steady, so using this method I'm likely to rule out a vacuum leak on a consistent dip of the RPMs (both the scanner and the rev counter hold normally, only changing when changing gears obviously)

To everyone else as well I've just swapped my fuel pump relay, and had a new fuel filter installed not too long ago. Will see what happens.

One of my specialists mentioned the camshaft management sensor/part (the small cylinder with a clear viewing sight in the engine bay, using the same loom as the crank sensor) might be the cause. Are they likely to crack under hot weather and pressure? or the supporting wiring.

Will update further on what happens.

 

I.m a really cheap guy , everyone always compliments me on that

Vacuum leaks can be checked with some shortcuts probably mentioned above

Could be an issue but it is overcome by the vacuum " supply " at the higher RPMs

The fuel pump can be directly powered with a medium jumper wire ( blade type wire ends ) between socket 3 and 5 , this will drain the battery with the keys in your pocket as hot at all times from battery

The camshaft position sensor ( CMPS ) is not used after a certain RPM in the starting sequence , reverts to CKPS , there is a adjustment on the CMPS unlike the CKPS that has none , The CKPS sensor distance to the missing gear teeth , just say nope to the goat rope

When changing gears ........................thinking for you , the engine ECU and the transmission ECU cross talk to each other as they danse together in regulation

There is a connector to clean ( transmission speed sensor inside ( 1300 ohms ( warm is when the sensor fails ) ) ) but would have to double check , special trick to removing connector a pic someone has made as I struggled with mine ( M'Lady Penelopy )

Pics on different flash drive

 

Hi Parker, when you refer to the transmission sensor you are referring to something different opposed to the wheel speed sensor
something like this?
And in addition some people (including my specialists) aren't sure if its either the cam sensor or crank sensor causing this stalling... interesting. What I mean by this is that they both suggest different things to it stalling in the heat...

 

You have 4 types of speed sensors on the X300 , CKPS , CMPS , transmission inside , and the 4 wheel

The CMPS is the only sensor that is a 3 wire hall effect sensor , the other inductor sensors will read the same at about 1300 ohms as a very basic meter reading , the CMPS at 600 ohms

The engine will start with the CMPS connector removed but takes more cranking revolutions without it's initial aid then not used

To clean the transmission connecter , it must first be pulled straight aft ( 1/8 inch ) to unlock and only then rotated about a 1/2 turn to remove ( top of connector to the car's left )

The connector if dirty only causes problems in the driveway as the car comes out of P or R into D from reading others ( very low speed)

The connector is on car's left side , no jacking needed

the 4.0 liter with the ZF4HP24 will defiantly have this and not sure on the 3.2 liter ZF4HP22 , mechanical kickdown system from my understanding

 

Hello all - Just an update on the current situation and resolution to the problem (hopefully)
If you are the person looking at this many years later with similar symptoms - Please check your Crank Sensor!
On consultation of a local Jaguar specialist, they suggested the sensor I had in was no good especially in hot weather
Aftermarket sensors (with a crappy 1 year warranty made in China) or sensors beginning to fail do this when the sensor connection between the crank and the sensor falter (over time they loose there connection ability) - Hot weather can increase this impact and lack of connection (something Australians are well aware of!)

In short - sort yourself a good aftermarket one or a genuine sensor replacement (The node at the tip of the sensor is coated in gold) - if it has intermitted as my symptoms and bloody hot!