So, I've been trying to chase this down for awhile now. Things have definitely improved, but still not ready for Interstate travel.

Basically, car ('95 X300 or XJ6 NA) starts up fine and runs great until it fully warms up. Then, if I'm just piddling around town, it's manageable but, once I get into the higher RPMs or if I step on the pedal or when going up a hill, the car loses power and surges. If I press the pedal hard enough to kick-down, the car refuses to downshift and instead just falls on its face until I left off the gas enough. Again, until it fully warms up (over 180 F), the car shows none of the symptoms and will accelerate without hesitation and changes gears smoothly.

Had the scanner hooked up while driving yesterday and everything looked OK, except, when I was cruising at 70 mph, and the power loss/surging was starting, I pulled up the RPM graph and RPMs were drastically bouncing from 1250 to 2700 range...even though the tach on the dash was holding steady at 2600. SO, I was hoping this latest discovery might help zero-in on the problem. I'm thinking Crankshaft Position Sensor (but it starts just fine?) or Camshaft Position Sensor either needs to be replaced or readjusted. Any help would be greatly appreciated.

CODES: P0340 & P1313

HISTORY & THINGS DONE:
I've owned the car almost a year. Drove it from NC to FL with none of these issues. Suddenly, one day it started acting up and actually stalled on the Interstate. I pulled to the shoulder, waited a few minutes and it restarted fine, but I had to take the back roads home as I could not maintain highway speeds.

Initially, I did a vacuum test, and had steady 17 but determined excessive back-pressure. Took it to an exhaust shop for flow test and underfloor cats were restricted. So, I eliminated any restriction in the underfloor cats. This helped, but problems reoccur once fully warm and under load.

Replaced Fuel Filter.

Noticed it was taking a long time to reach N on temp gauge, so checked T-stat. Replaced thermostat and now reaches N quickly and holds steady temp.

Just replaced all 6 Coils and New Plugs. When I was changing coils, I noticed that the thin wiring to the coil connectors were old and brittle, with some cracks. I tried misting water at night but saw no arching and saw no tracks when replacing coils. But, I went ahead and spent a couple days applying Liquid Tape to the wire insulation, slowly building up a more protective and flexible cover.

Just changed the Oil & Filter

I remember initially thinking it could possibly be the CPS, so tried testing the resistance. I don't remember the exact results but I understand it's not a fool-proof test.

THOUGHTS:
I have a Fuel Pressure Gauge, but I'm not sure how to take the reading on this car as there's no schrader valve on the fuel rail. Where would I T into the fuel line?
I was thinking it could be a failing fuel pump, so I ordered a new pump. It just arrived and I was about to replace it, but then I saw the RPMs on the graph yesterday and thought that might be more suggestive of a sensor failure. Even when the RPMs were jumping from 1250 to 2700 on the graph the car was cruising pretty steady at 70 mph. I could feel the surging starting, but I don't think the engine speed was actually changing as quickly as the graph suggested.
FPR - Was going to pull the vacuum line off and test as much as possible before dropping in the new fuel pump. But, in light of the new info....
Front O2 Sensor - The front O2 sensor voltage was changing, albeit not as quickly as I'd have liked to have seen, so it could probably use replacing but...

Anyway, I apologize for the long post but I wanted to provide any available info which might be useful in assisting diagnosis.

If fairly confident that it's a Crankshaft Position Sensor, I will order one as none of the local auto parts stores have one in stock.
If there's a way to really test them, please do share.
If worthwhile, perhaps even while waiting on sensor to arrive, should I try to adjust the Camshaft Position Sensor? I've read a couple posts on this procedure and think I can handle it.
Or, with a P0340 and the present symptoms, can I test the Camshaft Position Sensor or should I order?

Long post, I know.
I just feel like it's got to be something simple, as it drives just fine until it fully warms up. While warming up, it can climb a hill no problem and accelerate/kick-down, etc.
I was really hoping the new discovery of RPMs on graph vs Vehicle Speed vs RPMs on tachometer might be enough for someone to pull me off the dreaded fuel pump replacement I had planned for today.

Many thanks in advance for any advice/suggestions.

 

My list over and above what you have done.

Mileage is ??????, and that can be a key to some of my things. 160000kms (100000miles) is a "magic" moment

Crank Angle sensor, AND/OR the crazy connector at the front of the timing cover.
Fuel pump, and also the small wiring loom INSIDE the tank, that connects the pump to the lid.
Fuel tank venting. Remove the tank filler cap, go for a blast, still there, or gone?
Cam angle sensor, NOT a real problem item, and the fact it starts quickly, it sounds timed just fine.
Coolant Temp Sensor, maybe. They are cheap, so new unit wont break the bank. About $25 down here.
O2 sensors are a service item. Around the 140000kms is the figure down here.

 

Thanks for the reply, Grant. The car has about 135,000 miles.
I'll give it a quick run with fuel cap removed before I start messing with it today and see if it makes any difference.

Yeah, I figured O2 sensors were due but was really hoping to get it running better before I replaced everything that was "due"...at least, all at once. So far, Rear Shocks, Fuel Filter, 6 New Coils, Plugs, Water Hose, Thermostat, Air Intake Duct, Fuel Filter, $ for Underfloor Cats, Coolant flush & Change and, of course, the Oil & Filter change (8.5 qts). Oh, and just recently put on 4 new tires. My money tree is still suffering through its winter foliage!

My thinking was the O2 sensor might tell the ECM to adjust the fuel input, and I know they can cause rough riding, but would a bad O2 sensor cause the scanner to graph rapidly fluctuating RPMs when tach reads steady? I could very well be wrong.

I'd wanted to replace front shocks, tint the windows, and get some kind of stereo setup working but I've been chasing this problem instead.

So, I guess I'll go ahead and try to swap out the fuel pump since I already have the replacement and I can't get a Crankshaft Position Sensor today anyway.

​​​As for replacing the fuel tank, I've seen the "easy method" thread and the old fashioned way. I'd rather not cut the parcel shelf, but I will. How hard was it to disconnect the lines under the tank? Any other tips for the task?

The way the RPMs were graphed on the scanner last night, though, really got me leaning more towards a sensor. I've heard a failing fuel pump can sometimes only present problems after the car's warned up and/or under load, but my RPMs were changing by 1500 with vehicle speed and tach in dash both steady. I'd think, if the fuel pump was cutting in & out, the RPMs on the scanner should still reflect actual engine speed and they would likely dip with intermittent fuel pump... But changing so quickly between 1250 and 2700 RPMs? That seems excessive.
​​​​

 

Oh...and Coolant Temp Sensor? Yeah, I could test it and/or just order one if/when I order CPS. I've watched the temp closely since replacing the thermostat, though, and it seems to climb without any irregularities and then stay pretty steady once it reaches operating temp. I've also watched the graph of ECT on scanner and didn't see anything. But, it's cheap, so may as well.

Thanks again for your help.

 

Have you checked the ECM connector pins for corrosion? Much mischief has been traced to that. I'm not sure what parameters need be met for the transition from open-loop to closed-loop fueling to occur, but imagine temperature is one of them. Your scanner may be able to show the transition and then you could determine if that is the trigger.

 

Thanks for the reply Aholbro1.

Yes, I did check the ECM, in so far as I disconnected it and looked at the pins for corrosion. Then, I cleaned the connector and pins with CRC electrical contact cleaner. I did not do any testing of the ECM, like checking any specific pins with multimeter or anything.

The car does wait until it has warmed up enough to enter Closed Loop before exhibiting any signs of a problem. Before reaching Closed Loop, it drives great!

​​​​​​However, it's not as though the car misbehaves as soon as it enters Closed Loop. If I'm just piddling about at low vehicle speed AND low engine speed on a flat road, the car doesn't exhibit the symptoms. So, it's only after warning up enough to enter Closed Loop AND then trying to accelerate into the higher RPMs or trying to climb a hill. Although, it's able to handle an incline if I keep the RPMs low.

Hope that answers/helps clarify somewhat.

 

Don't fear the fuel pump R&R. How difficult was fuel line disconnect?

Let me say it this way....I've cut holes and shapes in various media (sheet metal, wood, plexiglass, fibreglass) using an electric sabre saw, with such media both clamped to a workbench and in-situ (door speakers in a Chevy pickup back in the day) and it was (by far) easier to disconnect both fuel lines than ANY of those cuts. I can't imagine hacking into the rear shelf under the rear windscreen (after having messed with the hi-mount brake light on the 96's) would reduce the degree of difficulty to the point it would be easier than the line disconnect.

You will need to raise the rear end for access. I used a jack and jackstands because the fuel pump relay had been burned up and although the car started fine and pulled into the shop without effort with a replacement relay, I didn't know how much life the pump had left in it and didn't want to risk running long enough to re-position to get it up on ramps.

You will also need the somewhat specialized fuel line/ac-line tools...but they are cheap and you probably should have a set of those anyway. Make the leverage tool pictured - As I recall, anything over 6" would've been too long due to a bend in the tube or other impediment to access. You need to cut-out a wide enough section along the longitudinal axis to allow it to slip over the fuel line. I used a radial arm saw, though I'm sure other, less injurious tools could be brought to bear. I don't think the notch you see in the end of the pipe was necessary, more likely that occurred when the blade snatched it away and flung it across the shop.....

https://www.jaguarforums.com/forum/x...quired-163902/

Best tip I can offer, and this applies regardless of which method of access you choose - work step-by-step from the checklist BOTH WAYS so you don't forget to make a key electrical or tube connection and have to redo it!

 

Agreed with that line R&R.

Access is tight, and Bandaids will be needed, coz for some Jaguar only reason, there is a sharp metal edge right at the exit point.

I inserted my plastic "special tool" that I got from the ElCheapo parts store, and pushed the metal line INTO the tank, and then pushed UP on the tool, and withdrew pipe and tool all in one not so smooth movement.

Pushing the pipe into the tank that very tiny amount, frees up the metal clasps just enough.

It took a few attempts, lots of foul language, but I was NOT cutting holes in that parcel shelf.

Did it again a few months later, the New pump was a screamer, and those pipes slipped out easy.

 

Heh heh...I did mine again a few MINUTES later, for the reason noted...and likewise, they slipped out easy.

Yeah, I assumed too much familiarity with the joint in my write-up, I suppose. It is most beneficial to push in, then pull...kind of like using a jack or other leverage device when trying to extract a lower shock bolt...you have to ease the pressure on it for a smooth release.

Also, listen for the "click" when you re-insert them then give them a good stiff pull to make sure it is seated and properly installed.

 

Thanks for the tips. I tried to give it a go today but ran into an issue and then started getting frustrated and losing daylight, so I zipped it back
together to save for the morning.

I got the boot all cleared out, depressurized, removed battery, etc. However, when I recently did some exhaust work, I didn't realize that
there were hangers for the rear resonators as well. I knew there were the two on the mufflers that side through the rubber mounts on the brackets
behind rear bumper but I guessed I just missed the two for the resonators.

Even with the car on jack stands, there was no way I could fit my arm through any gap enough to reach the two pipes above the differential because the exhaust pipe was in the way.

So, I bailed on it and figured I'd attack it with a fresh mind in the am. I'm just going to raise the car and remove the rear mufflers and rear resonators before trying to get to the fuel pipes. Then, when finished, I can reinstall the resonators properly on their hangers and then slide on the mufflers. I thought my mufflers were hanging a little lower.

After the tips and link to the detailed walk-through, and having gotten my feet wet, I'm feeling much more comfortable about the process for in the
morning. After trying to create unnatural joints in my arms, and starting to get a little pissy about the whole thing, I thought it best to revisit in the am, lest I rush and really screw things up.

It looks like, with the exhaust pipes out of the way, my fat forearms should be able to reach. I left the boot liners off and the required tools are ready to go. Hopefully, replacing the pump solves my problem but I'll be sure to post my results.

Thanks again.

 

Car on ramps, tail up.

You, slide under the car from the tail, head first, till you are looking at the snout of the differential.

Those pipes are just above and to the car RH side (your left laying under there) a tad. Easily got to from that area, but from the rear or side, NAH.

Some inenr lubricration for you beforehand will ease the frustration just a bit.

 

Hmm, I should mention that I have similar experience with my Mercedes engine acting up cold and hot. This happened after replacing an air flow meter which a workshop believed was the culprit for sudden stalling at low speed after a momentary rest of about an hour. With the new AFM that has a potentiometer and stuff, my horror began. Car was unable to hold steady at idling when engine is cold, but once heated up the lack of power and sudden surge kicked in. So I backtrack a little and asked the eBayer to send me another AFM just to make sure and ask the workshop to follow the protocol of adjusting the potentiometer and CO properly before giving me back the car. The second AFM has arrived, and I have yet to experiment if indeed it was the AFM and/or the workshop messed up last time. It may not be the cause of your problem, just mentioning it to you just in case. I would avoid pulling the fuel tank unless reasonably sure that it is the prime suspect. I would also try another scanner to verify if the data you saw from the first one was reliable.

 

I had a customer car that had the same faults (rough running and misfire under load at speed).

I tried sparking plugs, coils and new TPS. Finally replaced the CKPS with a known-good used parts and SUCCESS!! Ordered a new replacement and sent the car down the road.

bob

 

Yeh, I agree with Bob that the CPS is worth trying first, and it won't hurt your wallet much, and adding a CPS as spare would be a good practice. Also, the temperature-sensitive O2 sensors would be my next call.

 

Well, thanks to everyone for the tips/advice.

So, I finished replacing the fuel pump this morning. I got jammed up yesterday with the filler neck/filler seal, as it was so cold here in the mountains of NC that there wasn't much flexibility to the plastic.

I attacked it early this morning with a fresh perspective and was able to git er done w/out too much cursing. I primed the pump a few times and then the car started right up, seemingly a little quicker than it has been. So, I drove down the mountain to the nearest gas station and, on the way down, the car drove beautifully - good throttle response, smooth gear changes, and no issues using the J-stick to manually shift gears.

However, it's been making it to that gas station without any trouble, as that's right at about the distance where the car reaches normal operating temp since it's mostly downhill. Unfortunately, during the return trip to the house, I tested it with some quick accelerations and the problem is still there! Again, only once it's fully warmed up, and then at higher RPM's and heavy acceleration, especially when under load, the car sputters/hesitates/surges/loses power.

I'm inclined to think it's probably the Crankshaft Position Sensor. After seeing the RPM's fluctuate the way they did on the scanner's graph mode, I was leaning towards a sensor problem over fuel starvation, especially since it doesn't thirst for fuel at all until it's fully warmed up and enters Closed Loop.

I had already received the fuel pump replacement, though, and couldn't get a Crankshaft Position Sensor delivered before i leave for Texas tomorrow AM, so I figured I might as well change out the fuel pump. I was hopeful it would solve my problem but figured, if not, at 134,000 miles, I could just chalk it up to good preventative maintenance.

So far, in trying to correct this problem, I have:

Replaced Fuel Filter
Hollowed out Underfloor Cats
Replaced Spark Plugs
Replaced all 6 Coils
Insulated the wiring to Coils
Cleaned electrical connectors with CRC Electronic Cleaner
Replaced Air Intake Hose
Replaced Thermostat
Compression Tested each cylinder
Cleaned MAF Sensor

I'm hoping it's the Crankshaft Position Sensor! At least, it's an easy repair! Then, I will replace the O2 sensors. However, I'm flying out to TX in the AM so the repairs will be put on hold for the month as I won't return until 2/28.

I just wanted to post a status update and thank everyone for their tips/suggestions/advice and also the words of encouragement.

 

Wing Nut,
well done for being so philosophical about the fuel pump replacement not solving the problem. As you say, not a bad thing to do from a maintenance perspective, as are the other replacements you have made. Similarly, a new crankshaft position sensor is never a bad idea on an X300, and from what you have said, strikes me as a feasible suspect.
Whilst your post initially had me thinking fuel supply, your observations about the rpm readings tipped me towards an electrical cause. If the irregularities in the rpm readings were in any form of pattern, it would tend to point away from bad connections to a failing sensor which is supposed to be sensing something connected with reciprocation..... eg CKPS
Fingers crossed!
Ps You havent mentioned whether any codes were showing

 

So, I returned to my Jag the other day after spending March in TX. I left after replacing the fuel pump & figured it had to be the Crankshaft Position Sensor.

I ordered a new one & installed it, but now I can't even get the car to start! I never had issues with it starting before and thought I had zeroed in on this issue, but at least it was driveable. Before I left town, after replacing the fuel pump, I was able to drive it around the city and even gradually get up to 80mph on the Interstate. If I gave it too much gas, it would act up but...never had any problems starting.

So, I swapped the old sensor back in but still no luck.

By then, the battery was starting to wear down so I went and purchased a a battery charger. Slowly re-charged battery. With fully charged battery, I:

-Tried starting it wit a little fuel in the throttle body. No Luck.

-Checked for fuel pressure at the rail. I couldn't attach my gauge properly, but I seemed to have pretty good pressure. I cracked the nut at the rear of the rail and stuck tube in container. Fuel was coming out with solid flow.

-Adjusted Camshaft Sensor by setting #1 cyl to TDC and making sure dimple was in the center of the window.

-Checked fuses and relays

-Pulled plugs and they smelled of fuel. So, I dried them overnight and then tried starting it with pedal all the way to the floor.

-Checked for Spark. I was only getting a very WEAK SPARK! I checked for spark a couple month's ago and had good, strong spark. Not anymore all of a sudden.

-Swapped a couple of the new coils out with those I'd replaced. No improvement.

-Replaced Engine Coolant Temp Sensor

I charged the battery to its full strength. I think it read 13.2 when I checked 30 mins ago. And am about to try again but I could really use some help here. Electrical systems are not my forte.

I've swapped the ignition relay from RH under bonnet with horn relay from LH under bonnet fuse tray and re-checked fuses. I was going to give it another whirl and then swap the two relays for ignition in each heel board. I also swapped the larger black relay from behind RH headlight with the wire colors indicating its for ignition as well.

Other than that, I think I' may have reached the limits of my knowledge.

If anyone could offer some advice on what to try, I'd be much obliged. I'm scheduled to go out of town again and I'd hoped to drive it this trip. I really thought the new Crankshaft Sensor was going to be the answer.

 

Could you have accidentally disturbed any wires in the engine bay, under the car or between the trunk and cabin (when replacing the fuel pump), or forgotten to put them properly? My no-start saga (lots of write-up on Rose in this forum) was complicated by the fuel tank removal during which a plastic buckle holding the harness bypass between the trunk and cabin broke loose without notice and all effort to diagnose and fix the problem failed. The mechanic accidentally found the loose connection one day and it was a good start of the rescue.

 

I suppose I could have. Is there an easier way to check than having to remove that thing again?

 

One other thing to check for is Bore Wash (Google if you've not heard of this condition).

X300s are susceptible to this if the engine is started and then stalls or is switched off after a short run time (I saw in your other post that engine stalled but you didn't say how long it was running before that happened).

It's easy to test by checking the compression on all cylinders if you can, and easy to fix with a tea spoon of oil in each spark plug hole.