Hello: I have been having an intermittent problem where the engine (XJS, coupe 1992, 6 cylinder, stick shift) suddenly quits - it cuts out, all ignition lights come on like you are just about to start the engine, and I have to coast to the road shoulder and get out of traffic's way. manual transmission). Can be awkward on the highway when this happens at over 100 kph! When this happens, all dials - temperature, oil, voltage - look fine except of course, once it happens they go into the mode before you start the engine. If I wait a minute, restart the engine, it starts right away and runs fine. It doesn't seem to like it if I try to start it immediately. I have had this happen and then drive the 30 kms to my destination without any issue - the car behaves as though nothing happened. Though recently, it stalled like this three times on a drive - and it is my subjective impression it was more likely to do this if I was stopped at a intersection, traffic light etc. I am using highest octane gasoline so I don't think it is the fuel. Has anyone else experienced something like this, where apart from completely stopping for a minute, the car appears to function fine. Also, sometimes when this happens the check engine light comes on - but once it has happened is there a way to get the check engine code? Is there something else I should watch for when this happens.
I am taking the car in for service this week, but wouldn't mind helping with ideas of what might have to be checked. A concern, as always, is if the service person cannot repeat the fault.
Regards
Bill Mercer

 

I’m not educated about the process to pull stored codes on a 92, but I’m going to bet EGR Valve.

Next bet is TPS.

Before you take my money, do yourself a favor and pull the ECU plug in the passenger footwell and make sure the pins are not corroded.

Make sure the throttle body is clean.

 

From the forums I found these relevant quotes. If it was me id clear all codes and then drive till the problem comes up then..key off...on and note the code.

Just throwing darts I'd say it sounds like a plug or switch as in...loose ECU plug or your key ignition. I wonder if slapping the dash hard would provoke it, or going over a set of railroad tracks. Next dart...critical sensor input being lost for a moment - like on the V12 engine there is a coolant temp sensor if it unplugs its lights out instantly. But your car should be new enough to have the OBD code system.

 

Don't forget the crank sensor on those AJ6's. The XJ40 guys had lots of failures.

I think the test was, when the engine cranks but doesn't start, see if the tach moves a little, or not at all. If not at all, it's a faulty CPS.

Rob

 

When I first bought the 96 XJS, 6 cylinder, I had the same thing happen. It took several shut downs before the car finally awarded me with a code.

It was the EGR Valve.

At best, take it off clean it up and put it back on, although I never had any luck cleaning up an EGR. Worst case, you’re out $100 for the valve.

I’d take a stab at cleaning it up by soaking it in gasoline.

 

Problems like this can be tough to solve, for obvious reasons, as you are aware of.

Ideally every mechanic (pro or DIYers) would love to see only hard failures....which are generally easy to diagnose. But, naturally, all the testing and diagnosis in the world can go for naught if everything is operating perfectly well at the time of....... testing and diagnosis

Any decent mechanic will know to gently jiggle-test all relevant wires and connectors----engine sensors, ignition switch, relays----in hope of discovering a weak connection. That is, or should be, a routine step.Sometimes you hit pay dirt; other times not.

Guesswork is never preferred but not all guesses are equally painful. In some cases an experienced guess is a better and/or cheaper alternative to hours of labor ($$$) spent looking for a needle in a haystack. The crankshaft position sensor often falls in this category. These are a high-failure item (as already mentioned) so there's a decent chance of replacing solving the problem.

Other things (EGR cleaning, throttle body cleaning, and such) are never a bad idea just on general principles. You might get lucky. But t's money well spent even if the problem isn't solved.

If the shop doesn't come up with anything concrete I'd be tempted to have them check/perform everything already mentioned in this thread. No promises, obviously, but there's a decent chance your car will be fixed. A lot depends on your pocketbook and/or tolerance of the inconvenience of multiple return trips by going alá carte.

Cheers
DD

 

Hi Vancouver XJ6
Interesting comments. I drove to my service fellow today and it stalled twice - once on the 5 lane highway with me in the middle lane, trying to take the three lanes going left but having to coast into the shoulder on the right with everyone around me going 120kph+/-!
But the second time it stalled, I was on the highway and there was a series of bumps, and at the second or third bumps, with the car going a little hard on the suspension, the check engine light came on and the engine stopped. I have not noticed it related to bumps before but maybe I was not watching for it. Also the first stall was preceded perhaps by one minute or so, by a sudden kind of reaction in the engine that felt like a stall, but then it continued OK and then really stalled a minute later.
Again, as usual, if I wait a minute, and restart, it appears to run fine and I can continue the journey.

 

We had the same issue with our '95 X300 sedan (same engine), and it drove me nuts for over a year trying to find the cause. Turned out it was the ECU itself, and I had to send it out to someone who refurbishes ECUs. Never had the issue again.

 

this sounds like a fuel issue. When there is a lot of debris in the tank and suction screen in the tank is starting to get plugged, the debris plugs the rest of it and cuts off fuel. When you shut down, it falls back to the bottom of the tank and you get fuel pressure back and can drive until it sticks the debris up to the screen again.

 

You could well be right; but fuel starvation usually gives a bit of warning with a few hiccups, etc. I am not clear from the OP if the car is just cutting out like being switched off, or if it is dying over a few seconds.

 

While reading your post it triggered a memory of mine.
Of course it was a million years ago and I'm not even certain if it was with a customers car or even Jaguar related.
What I found out what it was, I do remember clearly.
My finger on my right hand was contacting the key and turning it 1/4 turn CCW.
Not likely that is your issue, but it had the exact same effect.

 

Folks
It turns out that a mouse had got into the air filter during the winter storage, and had chewed it. It seems small pieces were getting into the fuel system giving the engine check error message of "lean mixture". Now it is all cleaned up, no more stalling - at least so far!
Apparently the key is if you store the car over winter in a farmer's barn type of place, stuff something into the air intake so that a mouse cannot get in.
And, I suppose, when you go to start driving in the spring, check for this type of issue.
It is a relief that it is nothing serious and in a way, very funny!
Regards
Bill

 

Except for some sort of strong metal mesh, I would not put anything in the way of airflow.
Junkyards are full of cars that had debris sucked into the motor.
Almost one of mine too.
Many years ago a friend/mechanic rebuilt my carburetor for me.
He forgot to use the lock washers he kept in the air cleaner.
The car ran but it was very noisy.
My father and I had to replace all the pistons and a few of the valves.
Now I hardly ever let anyone work on my cars.
I appreciate all the good intentions but I can't afford that kind of help.