I've written about this as replies to other peoples threads, but I figured it was time to have a thread of my own. I have a problem with my 1996 XJ6 4.0 stalling while driving along. Without any warning whatsoever (not a sputter or anything) the engine just stops running. It's just as if I turned the key off. On cool days, or at night, it will usually restart immediately if I just pop it into neutral and turn the key. But if it's hot out it just won't restart until it cools off.


So far I've changed the ignition relay, the fuel pump, the fuel filter and the fuel pressure regulator. I also checked the transmission fluid level, as someone recommended, and as strange as it seems that it would be related to a stalling problem. After all this the problem, if anything, is worse not better.


I suppose it could be a vapor lock problem, but I don't understand why it should be such a problem this summer while it was not a problem for any of the previous six years I've owned the car.


In its present state the car is neither usable nor saleable. I'm beginning to think seriously about junking it. Yesterday it stalled and I had to leave it on the side of the road. I got a call from the police saying that it could not spend the night where it was; it would be towed. I had made up my mind that if it got towed I just wasn't going to go retrieve it - they could have it. But I went back to give it one last try and fortunately (or maybe not) it started and I drove it home. It did stall one more time on the way home, but it restarted after only about 10 minutes.


I'm about at the end of my rope with this. Any help would be appreciated.

 

I can see your problem as it's very difficult to diagnose a problem that isn't happening at the time. You probably need to be prepared to do some diagnostic work next time it happens. Can you replicate the problem with the engine running on your driveway?

You could do worse than to check out aholbro1's thread https://www.jaguarforums.com/forum/x...ngines-120221/

Whatever is making it refuse start is sure to be what caused it to stall.


If I had to take a wild guess it would be Crank Sensor breaking down. Does the Rev counter drop to 0 as the first sign of a stall? Next time it happens, pour cold water on the Crank Sensor and see if it starts - or try and induce a stall with hot water on the sensor.

If it was fuel related I'd expect some kind of chugging/misfiring before it stalled.

Is there any pattern to the failure - same time from start up, same revs, going around a corner - anything?

 

From what I've read, this is a classic Throttle Potentiometer Sensor (TPS) failure...except for the fact that it needs to cool off to start. Not sure that has been reported in the past.

Do a search on the forum, and you'll find many people have resolved their issue by replacing this part.

Two problems:
1. It's expensive. $500
2. You need a dealer to set the idle for you. (some people don't seem to need this)

Buy the part, install it yourself. It's simple. It will also give you the opportunity to thoroughly clean out your throttle body, which I guarantee is in horrible shape. If your idle is too high, then you'll need to pay a dealer $150 to reset it for you, but you could be lucky and not need it!

The only other possibility is the crank- and/or cam-shaft position sensor. Search the forum for that as well.

Good luck and please update us with any result, good or bad.

 

I don't suppose you've got any codes logged?

Given you've changed the fuel filter (the cause of my first round of running problems) my guess would be crank sensor. They're basically consumable so it's not a bad thing to change anyway. 10 minutes and a few scraped knuckles and you're done.

 

+1 for the cps (crank position sensor) not to expensive and an easy job .
Chris

 

I had the same problem and solved it by replacing the ECM relay located behind the right headlights in the engine bay. Remove the windshield washer fluid reservoir shroud and you'll see 3 relays. Outermost is the one. Swap it with the innermost (AC clutch relay) if its a known good relay. It's worth a try.

 

Thanks to all for the help. The car is now safely home in my garage and we've both had some time to cool off.


Here's a little more info: Early on I thought this certainly must be an electrical problem, from the suddenness of the stalls and their subsequent recoveries (back then it used to almost always restart while I was still coasting along, just by popping it into neutral and turning the key). There was no sputtering or coughing, the engine was just suddenly OFF. It seemed that only something electrical could happen (and recover) that fast.


Once however, when it did not restart, I took out my AC voltmeter and put it across the two CPS leads and had my wife crank the engine. Clearly there was a signal coming out of the CPS. After re-connecting the CPS I took my key fob and whacked the ignition relay a couple of times. THE CAR STARTED. Great, I figured. Problem solved. So I ordered and installed a new ignition relay.


But the problem was not solved; it continued to happen. And the more it happened the more I began to realize that it tended to happen in the same places along my daily commute. And it seemed to happen when fuel demand was high, such as accelerating away from a stop or going up a grade. That's when I began changing fuel-related parts, such as the filter, the pressure-relief valve and the pump. But, if anything, the problem has gotten worse, not better after all this.


I've also come to notice that the problem is much less severe at night when I drive to work than it is at midday when I drive home. This led me to the realization that temperature is a factor and that, if the car will not immediately restart, if I let it cool off for a while it probably will.


This, of course, brings vapor lock to mind, and I've done a little research and decided on a fuel additive I'm gonna try. But it still doesn't explain why it would be problem this summer (the coolest we've had here in New England in years) when it has not been a problem for the previous six years I've had the car.


Also, some have suggested fuel injector or spark plug problems. Really? Do you know what the odds are that six independent components would all fail at exactly the same moment, and then all recover at the same moment, and then do this repeatedly? C'mon. It's more likely that the sun will explode. Now it's entirely possible that a SINGLE component that they all have in common is failing, but that's a different issue.


I am on the verge of ordering a new CPS anyway, just to be sure. I can install that myself. But I'm just NOT gonna spring for a new TPS and the required dealer calibration. If it comes to that, the car's life is over.


Thanks again everyone.

 

Just one more note: I think I might try replacing the EGR valve before the CPS. I remember having a problem with that when we first got the car and it was my wife's daily driver. I seem to recall her complaining about it stalling then.

 

Next time you go for a drive, disconnect the coolant temperature sensor, only after the engine is hot. See if you get a stall then.

Just remember to hook it back up when you're done driving.

 

Vee is right !

Although i suppose will not solve the main problem, disconnecting the ETCS is a very good idea, for stalling issues feed back.
The engine has to be HOT !!

 

+1 to Vee.
You could check the resistance of the coolant temp sensor.

In addition, you said you changed the ignition relay, but which relay did you change?
There are several relays related to ignition power supply.

 

Back when I thought the problem was the ignition relay (one of two side-by-side behind the right headlight) and I bought a new one to replace, it I saved the old one. Today I swapped in to replace the OTHER of those two relays, supposedly the ECM relay.


It's a cool day today here in New England and I drove the car for nearly twenty miles before it quit. Also because it's a cool day I only had to wait about 5 minutes before I was able to re-start it.

 

Any updates on this? I am having the exact same problem out of my 96 XJR. Identical down to the cool weather and frustration.

 

had this problem for two years, we live in four season weather, runs great in winter when its cold snowy but come spring and summer acts up again.

Don't know why but we started keeping the gas take full, and have been changing the filter every few months, the cars does run better when we put a new fuel filter on and keep it full of gas. I had a bad habit of only filling up when it was below a 1/4 tank. the more we have change the filter the longer we have been able to drive before it starts acting up again. were gonna keep changing the filter every month or two as its gotten a little better every time.

also we just realized we don't hear the fan anymore when we shut the car off on hot days or when driven long distances, so we'll check that out in the next few days. were gonna check the intake manifold and intake tuning values been hearing a lot about that on the net from others with the problem hearing that been the problem for others., so we'll do that to.

the first time we change the fuel filter it was plugged solid, we had to break it open to see. haven't opened any of the others. I drove it all day all over the city and four hours on the freeway. Drove it from 8am until 7 pm before it acted up at all. let it sit for an hour drove fine the rest of the night. usually I cant drive 20 min. on warm days. but each time we change the filter it has ran longer before acting up.

Also I started using high test , I always used reg. unleaded. don't know if that makes any difference but since car runs better with new filter, figured less gunk in high test. anyway I would change fuel filter, open the old one see if its plugged even if you have changed it before. Ill keep ya posted on what we find out, or if I here anything else.

one last thing the map sensor can cause the car to do this but it doesn't make sense that its effected by the weather. My husband builds transmissions and works with regular mechanics hes fed up, and when he gets fed up he figures things out so im sure he will. hes been working on cars for 45 years, not just transmissions, once he gets fed up he don't stop tell he figures it out. so fingers crossed.

the first time we changed the filter the car had gotten so bad I couldn't drive 5 miles before it started acting up. the more times we change it gotten were I can drive it for quite awhile except under load. good luck

 

Hi bmandatyejames,

Welcome to the Jaguar Forums!

I have edited your post to add some line returns since large blocks of text are so uninviting that others tend to not bother reading them. Ordinarily I might also go to the trouble of adding some capitalization and punctuation to make the text even more readable, but your post is so long I think I'll just invite you to do so using the EDIT button.

We're a friendly group, so please visit the New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and post an introduction so we can give you a proper welcome and learn something about you, your husband and your Jag.

Cheers!

Don

 

Hi tsfo2,

I know how frustrating intermittent problems can be.

One component that I don't think has been mentioned is the Ignition Coil Relay, which provides the 12V supply to all six coils. If the relay is opening intermittently, or if there is corrosion on the relay terminals or in its socket base, you might experience a sudden loss of spark in all six cylinders simultaneously. And since the relay is located on the right front inner fender not far from the upper radiator hose and exhaust manifold, perhaps those sources of heat are prompting the failure.


Another relay that comes to mind is the Fuel Pump Relay. You've replaced the Fuel Pressure Regulator, but it works in conjunction with the check valve or non-return valve to hold pressure in the rail. I believe that on the X300 the check valve is in the Evaporative Flange on top of the fuel tank. If the check valve has failed (they all do, eventually), and if the Fuel Pump Relay intermittently opens, the fuel pump stops running, allowing the pressure in the rail to dissipate back into the tank. The sudden loss of pressure could allow the fuel in the rail to boil to gas, causing classic vapor lock and preventing a restart until the fuel cools and condenses back to liquid. It might be worth cleaning the relay socket in the trunk fuse box and either swapping the relay or replacing it with a known good one (I haven't checked the schematic but I think it's probably a 40A relay with an internal diode specifically designed for Fuel Pump duty). I don't believe the Evaporative Flange is still available new, but you can easily add an inexpensive new check valve in the fuel feed line before the rail. Below is a link to photos showing how I did it on our '93:

Welcome to Jag-lovers - Members Photo Viewing Page


Cheers,

Don

 

My 95 X300 only has two relays in that area. Which one is the ECM relay?

 

As I mentioned earlier in this thread, I had the exact same symptoms as the original poster. After replacing the fuel filter, fuel pump, spark plugs, and crank positioning sensor the car was still the same......When it gets warmed up it starts to die and cuts out. As a last ditch effort I replaced my coils with some cheap ones from Amazon (120.00 for all 6) and now my car runs fine. No more problems at all.

Its been almost a month and I feel confident that in my case the coils were the issue. Now I just hope these cheap coils last a while.

Ryan

 

Never mind, I found the three relays where they should be. Thanks guys.