XJ Executive 1997 R reg 3.2 auto

The car has an intermittent fault of stalling when I brake or slow down to stop.
If I keep the revs up with my right foot on the accelerator and brake with the left foot its ok but getting on my nerves.
I was told to try and spray carb cleaner in the throttle bottle housing but it doesn't seem to have made any difference.
Any ideas people please.
Thanks

 

Is it only when you brake? One area to check would be a vacuum leak in the brake booster. That can cause rough running or stalling.

May be other ideas.

 

Brake or just slow down,seems like the revs go low and it just stalls ?

 

So, any is there a check engine light?

 

No lights on the dash come on other than the battery light when the car has stalled.

 

My car was pretty bad about that a couple of years ago right after it turned 100K. It would stall completely and I would have to go into park and restart the engine. This normally happened after 30 miles or so driving. As time and miles went on it did it less and less including less severe. The only thing I did was clead the TB. No imediate effect from that. Now when it stalls it is normally when accelerating lightly from a stop and it is more like a hic up. If I keep my foot on the throttle it will regain smooth accel without a complete stop and is OK. This may only happen once every few weeks or even a month or so. In summary it seems to have almost cured itself. Now has 126K.

I have had a thought as to what causes it. I think the intereption is in the fuel injection system and not the ignition. All cylinders hic up at once and then go again quickly and run just fine. Now this could be a fault showing up in the EMC due to age. Or it even seems like a vapor lock. Now I know the fuel filter is near the exhaust pipes and could be getting hot and with todays fuel causing a buble of gas at low fuel flows. My plans are to change the filter, it needs it anyway. And put some insulation around it when reinstalling. Thats all I can provide right now.

 

Thanks for that,
I am going to get the fuel/oil and gearbox fluids and filters changed in the next few weeks and will see how it goes.

 

I've just got back from an 80 mile round trip. Pulled into a garage to get a drink of water. Went to pull out and the car stalled in the middle of the road. Flicked it in neutral and started and was fine ?????

 

Speaking from experience it could be the idle control valve. Went on mine, got a spare off ebay and it sorted it. Still does it from time to time if I don't use it regularly.

 

Hi Scorpio stu,

In addition to the other ideas you've received, believe it or not, your symptoms are a classic indication of low transmission fluid, and it typically does not trigger a fault code. In at least one of the Jaguar diagnostic flow charts for "Engine Stalling," the transmission fluid level is the first item to check. I have also discovered that over-full transmission fluid can cause similar problems.

It would be easy to rule out by first checking the tranny fluid cold and adding a little if necessary (but not over the COLD line), then go for a long enough drive to get the fluid hot, then follow Jaguar's instructions for checking the fluid, which is something along these lines (please double check my memory in the Jaguar manual):

Park on level surface

Leave engine running

Put your foot on the brake and move the gear selector lever through every gear position allowing the transmission to fully engage in each gear

Put the lever back in Park

Leave engine running

Open hood/bonnet and step out of the car to the left side of the engine bay

Check the fluid and ensure that it is exactly at the HOT line on the dipstick, no more, no less. Add fluid about 1/2 pint at a time. If you accidentally overfill, use an inexpensive fluid transfer pump to remove some fluid.


If you do find that the fluid is low, you'll also want to track down and repair the source of the leak, then do a full fluid change.

I hope it's something this simple.

Cheers,

Don

 

Where is that located ? Easy job to replace ?
Thanks for taking the time to reply.

 

I'll try that today Don thank you. It does seem the revs drop in slowing down and that's when it stalls so either low fluid or the idle control valve. At least I'm getting somewhere. Thanks for taking the time to reply.

 

How's your CKPS (crank sensor)? I had the same symptoms from an old one that was going intermittent on me.

 

Exact same symptoms I had with my XJ6, and after simply replacing spark plugs, all was fine. No more stalls, not one! How old (what mileage) are your spark plugs? If you don't know, then replace them. So easy. So cheap.

I spent many hours troubleshooting everything I could think of. I never came up with a definite cause, until I thought to try new plugs, for lack of any other ideas. The old ones had about 25k on them. Fixed it! This engine is sensitive to spark plugs.

 

New cps made no difference.

 

Hi ok I checked the gearbox fluid level and spot on. Reading another thread I was told to see if it's the idle control valve se done thing. I got one bolt undone but the other side is buried and can't seem to get a socket or spanner on the 5.5 mil nut. I did unplug it and it seems fine and sitting around 1000 revs. Does it mean that as I've unplugged it and it's not stalling that that is the problem ?

 

Car has done 134,000 miles and no idea about the plugs

 

Hi Scorpio stu,

I'm glad you ruled out the gearbox fluid level.

Getting a socket on some of those screws around the throttle body can be a hassle. I find that it sometimes helps to use a universal joint between the socket and an extension that is 6 inches long (or longer if space permits). The fact that your engine is idling at around 1000 revs probably indicates that the IACV is stopped in a position that is allowing more air into the throttle than it should normally receive at idle. The higher idle speed may also account for the fact that you haven't experienced the stalling, since the higher idle is somewhat equivalent to pressing the accelerator pedal as you've done in the past to keep the engine from stalling. So you probably still need to get the IACV off of the throttle body to check it for carbon and gunk buildup and clean all of that out.

You mentioned in your OP that you had sprayed carb cleaner in the throttle body. If gunk buildup is part of your problem, spraying cleaner into the TB probably won't remove enough gunk to resolve the issue. The gunk builds up on the back side of the butterfly valve and in the bore behind the valve. Most of us have found it easier to remove the TB to do a thorough cleaning, which would probably also make it easier to remove the other screw for the IACV.

Other things that are known to be related to intermittent stalling include:

1. Failing fuel pressure regulator (FPR), often in association with a failed fuel pressure check valve or non-return valve. The FPR is on the forward end of the fuel rail and its job is to maintain +/- 40psi in the fuel rail to supply the injectors and to properly atomize the fuel. The check valve is part of the evaporative flange on top of the fuel tank, and it's job is to prevent fuel pressure from leaking back into the tank. Over time both the FPR and check valve are known to fail. The most common symptom is hard starting, but under some circumstances a loss of pressure in the fuel rail can lead to momentary fuel starvation. An easy check for one failure mode of the FPR is to pull the vacuum hose off the FPR body, crank the engine briefly, then check for the presence of petrol/gasoline at the vacuum fitting on the FPR. If it's wet there, the diaphragm in the FPR has failed and not only can it not hold pressure, it is also allowing unmetered fuel into the intake manifold, leading to an over-rich air-fuel ratio (AFR). Note that even if there is no fuel present at the vacuum fitting, the FPR may have failed and may not be holding sufficient pressure in the rail.

2. Resistance build-up across the Mass Air Flow Sensor (MAFS) electrical connector (open the connector, flush with zero-residue MAFS or Electrical Contact Cleaner spray, inspect for oxidation or other contamination and use a fine soft brass brush to clean the pins if necessary, then flush with spray again, allow to dry and reseat).

3. ECM ground stud loose or corroded (for location(s) check the Electrical Guide available in the download area of this forum - off the top of my head I think on RHD X300s the ECM uses ground studs at the RH A-pillar in the driver's footwell and on the RH inner wing/fender inside the engine bay). Remove the nut from the ground stud and use zero-residue electrical contact cleaner spray and a small wire brush to clean the threaded stud, all the eyelet terminals on the wires, the nut and any star washers. Some recommend using sandpaper for this job but you really do not want to create scratches on the terminal surfaces, which will promote future corrosion.

4. I recall a TSB about stalling when the transmission is shifted into D or R due to an issue with the torque converter control valve not working properly. It seems possible that a similar issue could cause intermittent stalling while traveling in Drive. It seems possible that a transmission fluid flush and change might improve a sticking valve.

Please keep us informed - hope you track this down soon.

Don

 

If the Throttle Position Sensor (TPS) does not tell the Engine Control Unit(ECU) or (ECM) that the throttle is closed, the Inlet Air Control Valve(IACV) (you forgot that one, Don )is not allowed to make control movements, so add the TPS to your list.

 

Firstly thank you all for the replies. I only have one more day off before I'm back on shifts so time is running short.
Couple of quick questions
1. Where is the tps located and is it easy to change ?
2. When I get the icv off does it have to be replaced or can it be cleaned and if so what with. Thanks again.
3. Will I damage anything if I drive without the icv unplugged ?