Having an issue with my 1996 XJ6 4.0 where when the car is sort of cold (I say this because by the time I reach the end of my neighborhood im at operating temp, and from here on out it wont happen, the car will stall if I come to a slow stop. Not sure what is causing this as its hard to narrow down, and somewhat inconsistent.

No check engine light (with the exception of one time it did throw one for engine speed)
After driving for about 10 miles it will not happen.
Sometimes it will go into limp mode after you start it back up, and will stay in 2nd gear, but if you let it sit for a minute it and start again the trans light will go away and it go just fine.

Here is what I have replaced this year (the problem started sometime after bringing it out of hiberation)

Coils, Spark Plugs, Valve cover gasket, Valve cover itself, and camshaft positioning sensor.

None of this seemed to change the way it ran, or how it did this.

Any ideas? I ordered a new fuel filter and will replace this next, and also have run multiple tanks of gas through the car.

Idle air control valve? Would replace but the issue is I cant seem to remove the bolt on the right side of it as the intake manifold is in the way, any tips on this?

 

decel stall is an IAC usually. consider getting a used one, i think i burned through like 3 aftermarkets that would kick the bucket after a couple thousand miles and give you exactly that. you can't rule out a bad TPS either, they do weird things on their way out.

 

The IAC valve bolts can be stuck and glued in with loctite and bolts break off , many have from reading , a throttle body internal cleaning while there would be a good idea just do not remove the TPS sensor on very bottem ( Hint : I had the TPS sensor connector missing lock metal bar from previous owner as connector was just " sitting " on there )

Vee has a IAC valve exersize and reset

There should be a gasket on the IAC as some are missing ( this effects true poppet gap position )

Heat needs to be applied from the iside of throttle body to loosen loctite

There is no way of reading the IAC has arrived to the commanded position , The EGR does as EGR_ERROR pid on a ELM 327 device as target value 0 %

Someone did mention back that by cleaning the EGR he recovered his idle
Fuel injector cleaner in tank , Chevron a recommended brand , very short pulse times on injector and lagging injector would ...................

There is a thing that acures at very low speed of a on the transmission connector comprimized as there is a speed sensor inside the transmission and this signal is used as the engine and trans dance together up and down

In valve cover gasket replacement there are 2 " D " cutouts that can fall out of place on installation and leak on very rear and then down on transmission connector

You can run you finger along the rear edge of valve cover and feel for a blown out seal as the Ds falling out of sealing

Fuel filter flow arrow points car outboard and there should be O - rings down inside hard to see filter fittings .......................ask me how I know

To improve your fuel pump performance swap the relay with I think the one nex to it as the same part #

Engine speed CEL as P0335 and not P0340 for cam position sensor appears rarely as not reliable , any of the aspects of the sensor's single wire signal usage like fuel pump enable , tach gauge , and spark / fuel timing can fail without giving a P0335 code

You can have grime on the face of the Crankshaft position sensor effecting how it picks up on reluctor missing tooth , this is different than connector clean

A good CKPS will read about 1300 ohms as a basic meter reading , not a Jaguar spesific part but commonly avail ordering in at local parts store

 

IACV is cheap enough to replace. I have had good luck with cheap aftermarket sensors. They are common. Make sure o-rings are added as needed. For some reason they never come with them.

EGR could be the culprit here. This is my guess. I have had the original go out on me. Happened like you say you’re experiencing. One time when it stalled out, it finally awarded me with a code. Make sure you buy a new gasket with the EGR valve, since it is sold separately.

Crankshaft Position Sensor could also be dying. Again, common part, not expensive, and shouldn’t take you long to change.

Lastly, Coolant Temp Senor. Again, inexpensive and easy to change.

I forget whether the EGR or the IACV have the 5.5mm bolts that will snap if removed without heating it up first. They have been loctited in place, so heat the bolts and be careful.

As you can see, all of the suspects are parts you can certainly replace yourself. I think only the EGR is close to expensive.

Good luck and report back!

 

EGR is the same as one of the 3800 GMs. they’re cheap af

 

I have bought two in my lifetime. Both times approached $100. I opted for a name brand aftermarket.

 

There is a trick to removing the on transmission connector as a different style

First it must be pulled car aft 1 / 8 inch to unlock and only then rotated connector's top edge to cars left , normal counter clockwise off only a 1 / 2 turn

Someone made a pic that says a thousand words

No car jacking and on cars left as you dive