I am a new (old) Jag owner, I bought a 1997 XJ6L locally from a Craigslist ad about 3 months ago. An elderly couple owned it for the last 17 years, having bought it at a Jag dealership as a "pre-owned" model in 2000 (I checked vehicle history). It had about 150,000 miles on it, and just over 152,000 now.

It drove like a dream for the first month and a half, and I was super excited to be a first time jag owner. I had the fluids changed, and fixed a bunch of small cosmetic issues inside and out, but did not have any serious work done and started driving it as a daily.

About about 6 weeks of ownership "the problem" starts. The problem is a random "cutting out" of the engine. Throttle position and RPM does not matter, it will do it under load, at speed with no load, and at idle. The engine feels like it just "turns off" for a second, and then comes back on. As long as I have some RPMS or road speed, it kicks right back in and keeps going. But at idle, or low rpm it will cause a stall. When it happens the dash, aircon, power steering, brakes, and internal electronics all keep working fine.

So, I found this forum and started looking for a solution based on others with a similar experience. Here is what I've done so far:

1. Took the car to a local mechanic I trust. He scanned it and found engine misfire codes, so he suspected the coil packs. They are newish, not the originals, and he thinks replaced in the last year or so (this is also what the previous owner told me), but they are not OEM. He looks them up, and Jaguar wants $420 each for 6 packs. I tell him that's a death sentence for me, as I cannot afford a ~$2400 repair. I ask him to check the spark plugs for age/brand, thinking maybe the previous owners put in "better" plugs that are not compatible. He checks them and finds that 2 are not seated fully (hand tight at best, not torqued down) and these are the two coils misfiring. These two show evidence of blow-by. Also, all the plugs are old and crusty. He replaces all of them with the correct Champion plugs (RC12Ycc) gapped to .035 as the manual recommends. The car runs perfectly afterwards....for a week.
2. I go to start on a Saturday morning and get a "no-crank" scenario. Gear shift interlock won't budge, and no remote keyless or any central locking functions are working. I check all the fuses, and find no issues. I research, and narrow it down to the "body processor module". I buy an old one from a working car off ebay and install myself. The car works again! But central locking is still dead (no keyless, lock button does nothing, locks won't go up and down with key in door, etc.) I don't care, though! My jag drives again!....for four days.
3. The original problem shows up again. Same symptoms, nothing has changed. Except this time, I can't get it out of the driveway because it insta-stalls upon startup. Engine cranks, catches runs for a few seconds, then stalls. I call a friend/mechanic who comes to my house and hooks up his pricey diagnostic tools and reads air/fuel sensors. He says the MAF is dead, and showing 0 signal. He suggest that the MAF cutting in and out on its way to death could cause my previous symptoms, and now its gone completely. I look up an OEM MAf, Jag wants $1200. F that. I buy an old ('97) MAF pulled from a working car from a parts dealer locally. Install myself, also clean the whole air intake (a little dusty), replace air filter (totally dusty, with leaves in it), and clean throttle body (not too bad). My car works again!...for 1 whole day.
4. Confident I've found the problem and fixed it myself, I take the car and my fam to my father's home (about an hour away) on fathers day. It drives perfectly the whole way there. When it's time to leave, it returns to insta-stalling, with the same "cutting out" symptoms from before. My father and I pull all the spark plugs and check the gaps (no issues), coil packs appear to be seated correctly, we cannot find any loose or frayed wiring. We check that all ground points are clean and tight. No solution. My father drove my family home, and I arranged for a tow to a shop close to my dad's house that he recommended, because the owner/manager is a friend. Its an independent shop, but "european specialists." I called first, and spoke with his friend who assured me he knew the model and the quirks.
5. I will not go into detail about this experience, but it was negative. The shop kept it for 6 days, and diagnosed it with a failing/intermittent Crank Position Sensor. $470 later, I have a brand new CPS on the car. I pick it up, drive it home, angry at the expense but relieved to finally have my car normal again, and sure that this expensive shop made an accurate diagnosis. Then it stalls out 5 minutes from home. Same symptoms.
6. I read forums. I read manuals. I read posts from the UK, yahoo ansers, service bulletins, etc. What have I not done yet? Fuel Filter! That might cause this symptom if its super old/clogged. Considering the spark plug situation, it probably wasn't replaced recently. I pay a local shop I trust $40 to put it on a lift and replace the filter with an OEM Jag one ($30). The old filter has fuel in it that looks like pond water. With my fresh new filter, I drive away with perfect idle, perfect performance, until "the problem" returns again 15 minutes later.

At this point, I have no idea what else to check. My wife is already telling me to dump this car, but I love it (when it works). When the engine cuts out, it feels like someone is "flicking a light switch on and off", and it has gone days in a row (with longer drives) without having "the problem".



Most of the time, a code is not stored when this happens. The CEL will "blip" on when the engine cuts out, but then turn off again when it comes back on. However, it has stored codes on occasion. Here is a list of what I've pulled from it, with the date:

• 5/12/17 - P0420, B30F4, P13B0
• 6/17/17 - P1790, P0727
• 6/28/17 - P0300, P0305, P1790

Here's a video of what the dash looks like while the "problem" is present, shot today: (ignore the transmission light, its in "limp mode" because I had just restarted it from a stall. Limp mode always goes away after it sits for a minute.)


The loss of the BPM and Central Locking at the same time makes me think an electrical short somewhere, but where? No fuses are blown, I went through them all on two separate occasions with a multimeter.



Please help!

 

Firstly, Welcome to the Forum.

When time permits, please do an Intro in the New Members Area.

I will digest more of this later tonight, when I have more time to think.

The fuel pump., and or fuel pump relay, are a known issue with these cars at about the 100K mile mark. Being EFI, if the pump splutters, so does the engine. The relays get HOT as the pump ages, and the usual mode is a dead car, but not always.

I would also be having a good close inspection, as in remove and clean, the engine earth strap. That sucker will reek havoc.

 

I would check fuel pressure and the fuel pressure regulator. I would also check the electrical plug connector at the ECM, some people have reported bad corrosion at this connection.

 

On reading your post, my mind was turning to fuel pressure/ supply, so I would agree with Grant and Scotlads suggestions.
Having looked at your video, I would comment that your transmission fail light might be another clue, as in normal circumstances it should not be on when the engine is running. I know that you have said that it goes out again, but it should not be on when the engine is running, and should extinguish immediately.
One of the X300 foibles is that the transmission light doesnt just indicate problems with the transmission, so it isnt necessarily an obvious clue, but it is a clue.
Have you checked the transmission fluid level? engine cut out at low speed is sometimes connected with low fluid level, and it is an easy thing to check and eliminate.
Having said all of that, I would still think fuel, and would perhaps be thinking fuel pressure regulator, given the way your engine cuts in and out.
Hope this helps.

 

Others have chimed in.

The main ECU connector is a well documented issue in some markets. UK and Tropical type climates seem to top the list.

The electrickery connector lead from the TOP of the fuel tank lid, TO the fuel pump itself, is also a problematic item, causing erratic pump operation, and eventual failure.

In the RH engine bay fuse block is a BLUE relay. This is one of many Ignition relays on these cars. This one supplies 12v to teh Crank Angle Sensor, and many other items. It fails, and also gets hissy, and its simply old age related.
Memory????, it is only a standard 4 pin relay, nothing special.

Thats it for now.

 

Thank you, I did go drop an introductory post in the new members area. As I had only ever browsed the X300 forum, I wasn't really paying attention to the rest of the areas.

I do not have time to reply to all responses this morning, but I will chasing all of these leads and will update the thread.

 

On initial reading of your post I thought fuel issue as others have said. However, the sudden movement of the tach shown in the video is suggesting to me that the signal is being lost momentarily. If it was actually showing a drop in engine speed then I'd expect a smoother transition.

So I think Grant's suggestion of the ECM Relay is where I would start (although on my car it is black not blue and is interchangeable with other relays on the block). There is also two large electrical connectors in the same area (lower down) that can cause a similar issue. Check them for corrosion.

Here's a couple of posts that may be of interest.

https://www.jaguarforums.com/forum/x...m-relay-88247/

https://www.jaguarforums.com/forum/x...367/?styleid=7


Also attached is diagram of where the relay is

 

Any thoughts from viewers on the transmission connector causing the tach signal to drop out ? Common denominator with the lights and 700 codes . Easy / cheap fix if it is the issue . Left rear location , don't need to jack the car . Fuel pressure regulators are around $ 80 and they don't last forever so you my be due anyway down the road . You can change it yourself , just use 2 wrenches to not twist the fuel lines . Bleed the trapped 45 psi fuel pressure first . I bypassed all the wires around the Papa Indy 1 connector below the windshield washer fill cap with environmental splices based on corroded condition . You can swap the ECU relay with either the headlights or the fog and the fuel pump relay with ( ? ) or just jumper across the power half of the relay . If you jumper the fuel relay and it resolves your stalling it will tell you if there is an issue with the ECU controlling that relay or a floating / lifting relay . Lots of current so recommend disconnecting the battery . If this shows anything don't buy an ECU yet for there are control wire repairs that we'll look at later . Don't forget the large ground by the starter .

A $8 ( shipping included Ebay ) laptop or smartphone ELM327 hookup to your ECU may show something as live data a trip log as you are driving around at the point that it stalls . Not like a machine in a shop . Way beyond a simple code reader . One of the PID's that you will be looking is the Crankshaft sensor . You would be looking for that signal bipping to zero that you wouldn't see on your cars gauge because of gauge dampening action . Adjust your ELM327 to the highest data sample rate .

https://www.ebay.com/sch/i.html?_fro...&_skc=50&rt=nc

Hope this helps you keep your Jaguar , Parker

 

Thank you, I have already picked up one of these bluetooth OBD readers and the Torque phone app. I'm definitely going to try this once I feel confident I can get it on the road.

I live in a high traffic area, so there isn't really the opportunity to test drive it to graph signals without risking stalling out at a busy intersection.

 

You might be able to duplicate the failure in the driveway at idle without putting it on the road . Tap and wiggle all around the suspected relays and connectors to see if you can see anything as well as inspect and clean the Transmission , Papa Indy 1 , and ECU connectors . Can't hurt and you'll get them back in shape .

 

I know you replaced your CRANKshaft position sensor, but I believe you should investigate replacing your CAMshaft position sensor.

Crankshaft Position Sensor was a good guess by the shop. It's nice to cross that one off your list.

Although aftermarket coils stink, I don't believe they can cause this problem. In the future, you can find OEM, Made in Japan coils for less than $100 each. You should plan on working that into your budget for the eventual need.

I'd also suspect the TPS, which is an expensive part as well. I don't believe that can be the culprit if your car is shutting down at idle. Someone else can correct me. I am aware that this part DOES create tons of weird, inconsistent issues, so I cannot cross this one off the list for certain. Even a cheap used one should solve your problem.

 

Here is an update:

This morning I monitored fuel pressure with the OBD reader, and it appears to be consistent. The pump doesn't seem to be malfunctioning.

I removed the ECM and could see no corrosion or issues, connections were all clean and bright.

I found the engine ground strap from above, and it does not look nasty from the best angle I could see. I'm unsure of how to get to it to remove without using a lift, though.

I swapped the ECM relay with the A/C clutch relay. Neither appeared to be corroded or damaged. The car ran perfect, smooth idle and no dropping out. I took it for a 2 mile drive with no issues. Stopped and started it a few times, again no problems.

I'm not calling it "fixed" yet, because this problem has been so intermittent and I have gone days in the past without the issue coming up.

I will update this thread if it happens again, and/or when I do additional work.

 

My recommendation ( and I could be wrong being I only have experience on one car ) would be to leave the TPS alone for now . Based on the cost of part , difficulty in replacement , and possibility of requiring a Jaguar shop only ECU ' reorientation " there are lesser intrusive things to do unless you have specific information pointing to the TPS by codes , ELM327 readings , or the process of " things that are left " or advice given . You can test the TPS with the engine on but not running by making a test point in a more accessible area as the wires run across the fuel rail . I did this with mine to ensure the my TPS is in range and has no bad spot in throttle range . What you are looking for is 0.60 plus or minus 0.02 volts at idle and no bibs in the needle of an old school needle style meter as you throttle through . The throttle body area can be very badly gummed up by crankcase gasses and with the TPS being on the bottom I highly suspected on mine that some oil may have migrated into the sensor . You can remove the sensor from the top with a lot of patients but I would recommend to remove the throttle body itself so you can turn it over to work on . I tried to get some cleaner into the sensor but failed . I had already bolted the throttle body on so I did the TBS removal the hard way . The XJR supercharged throttle body is from what I have read a whole different animal and is a lot harder . What I found on mine was the electrical connector metal locking clip was doinked off and missing so the connector was just sitting on there . What you can do is at least remove and clean and protect the connector for in service integrity .

 

One thing to keep in mind is that the ELM327 readers will calculate, fudge , fake , or make up things to make there model have more features then the competitors so they will sell more . They will even give you a 0 - 60 time with the wrong car data perimeters . The world is a lair's game folks , just ask the President ( ? ) . Without a true sensor for fuel pressure on the X300 I believe you are seeing a phony made up number and not a true reading . On the engine ground strap the area of concern is under the attaching hardware that you can't see .

 

Update: Took the cat on a longer drive and experienced the same issue, though less frequent and did not stall out.

I'm now convinced that something electrical is breaking circuit, possibly with road vibration...when I tried to graph sensors during the drive, when the tach did its sudden drop the OBD cut out and stopped recording. I then got a message that the OBD port had malfunctioned, but when I took it out and reinserted it worked fine.

I'm planning on taking a look at that ground strap next, as well as jiggling/tapping the rest of the relays and wiring I haven't checked yet. Are there any tutorials available to assist getting at that ground strap in my driveway?

 

Hard to get to the ground strap hardware, option would be to make an alternate engine block ground path to a firewall ground post as a troubleshooting step .

 

Update: Started the car in the driveway and went through and tapped/jiggled all electrical connections related to ECM/sensors/wiring connectors that I could reach. Took a long wooden dowel and tapped at the engine earth strap.

No issues anywhere, and I had it running for about 20 minutes.

So I took it out on a drive, as it was early and traffic was light. Everything worked perfectly, no cutting out, no misfire, idle was locked at ~730 rpm. I drove about 10 miles over 20 minutes, including a "stress test" of full throttle acceleration from 10mph-70mph merging onto the highway. My OBD reader recorded the whole time, and showed no faults.

The only notable thing that occurred was that at one point the driver's seat adjusted itself slightly and the steering wheel adjusted itself down. This is remarkable for two reasons: first auto adjusting seat and steering is weird, and second, the steering wheel adjustment has not worked since I purchased the car. It had been frozen in a position that was comfortable enough, so I figured I would look at repairing somewhere down the line. But now, after it kicked in and adjusted itself, the steering adjustment works again in every direction.

I'm absolutely mystified as to what is going on. While its good to have a successful drive, it makes it very difficult to rely on this vehicle as a daily driver if I can't find the problem and fix it because it is so intermittent.

 

Try turning the " auto " mode to the " off " position by rotating the larger and aft of the 2 knobs on the column counterclockwise or top to forward rotation . This commands I believe both seats and columns to stow ( opposite of column down ) as you remove your key on exit . This may isolate it toward the issue ( s ) or hold it and not be a distraction . You can break the issue into 2 parts one being column frozen ( and now free ) and the other being both column and seat uncommanded . To hold it steady try the " off " mode as you test drive the engine . Back later with some suggestions on the frozen plus the uncommanded movement . Are you using the Torque version of the ELM327 in the live data mode and not codes for engine troubleshooting if it accures again ?

 

The mode on the steering column was in "off" position the entire time.

Also, here is what I recorded on my trip today using the Torque phone app, which captured an occurrence of the issue. I've trimmed it to the relevant portion. I took it on a 10 mile trip (5 each way), recording data the whole time. The first 5 miles, from home to destination, were perfect no issues, nothing funky in the data. The return 5 miles were perfect until the final half mile from home, where "the problem" happened one time. A very brief (less than one second) drop in the tach, with a quick "blip" of the CEL, then right back to normal. Here's what the graph looks like, the issue happened right at the 12:50 mark:



This sorta confirms my suspicion that something electric is cutting out the ECM communication with the sensors. The car ran fine for the next half mile, after that half-second cut out, but the OBD did not read any more data from that point on.

Anyone else get a different idea from this?

 

You can electrically isolate the steering and seat to hold it fixed . After lunch I'll list through the precautionary steps . The perimeters that you should be looking at will be the tach , rpm , crankshaft position sensor , thouttle position sensor , mass air flow , and beleive it or not the engine coolant temp . What you are seeing is the effect and not the cause . I could be wrong . I do see your point of maybe it is a interruption of power . Have you checked the condition of both sides and both positions ( 4 ) on the ECU connector ? Mine has sockets on the car side of the connector that was not pinching the pins on the ECU . The sockets require a 2 pronged removal tool so a singe prong would damage it . While you are there clean the " case " ground of the ECU . I cant find my clarified schematic for the engine management wiring . It's somewhere .