my 97 xj6L, out of the clear blue, just started to run rough and shake on acceleration. 160K miles on engine but always ran perfect. I replaced the champion spark plugs to nkg iridiums (champions were in perfect shape but changed them anyway), replaced the egr valve. Still no relief, gas mileage drastically went down and rough idle too. Appears like it is missing on cylinder 5. Do I change the coil packs next?

thanks for any help.

 

Lots of "could be" possibilities but coils are a common problem.

With an ohm meter you can check them. You're looking for .75ohm primary resistance.....the resistance measured across the pins in the connector.

And/or you can remove the coils and examine them (and the sprak plug wells) for telltale burning/charring. Lacking of cahrring does guarantee that a coil is good, though.

With the engine at idle you can unplug the coils one at a time. Obviously the engine should become much rougher each time a coil is unplugeed. If you come across one where there is no or very little difference, that's your culprit.

Some have reported the scenario where if one coil goes bad, the others are not far behind. I'm in that group....but many others are not. I wouldn't necessarily suggest wholesale replacment of all coils at this time but be ready for the possibility of future failures.

I would not recommend low priced, brand-x replacements. Tempting, yes, because the genuine Lucas brand coils are very expensive. But the low cost replacments have a reputation for short lifespan. Been there, done that.

Also, has the crankshaft sensor ever been replaced?

Cheers
DD

 

I would also suspect the coils.
Dead coil case is the most likely when you feel miss fires.


I don't suspect the crank shaft sensor in this case. Generally speaking, when it has gone bad, the engine will stop suddenly though it idles smoothly.


You don't have to buy Lucas OEM, it will be okay as long as it is made in Japan.

 

I agree with all of the above, BUT, I would put the old spark plugs back, just for giggles, and see if anything alters. It will cost NOTHING, and I have experience, and read here and elsewhere that for some wierd reason these "fancy" plugs just do not like our set up. No idea why, waaaaaay beyond my brain cells I am afraid.

Just a suggestion from way down here.

 

Ok, I ordered 3 coil packs from a parts car over internet (3 for $50). I have not changed the crank shaft sensor. Where is the crankshaft sensor and what does it do? Is it easy to get at? etc...

thanks,

conrad

 

where do I find the crankshaft sensor?

 

It is in front of the engine, right above the crank pulley.
You can see pics here;

ƒWƒƒƒK�[X300�^XJS�@ƒ�ƒ“ƒe�î•ñ�•ƒp�[ƒc”Ì”„�@�`ƒNƒ‰ƒ“ƒNƒ|ƒWƒVƒ‡ƒ“ƒZƒ“ƒT�[ƒuƒ‰ƒPƒbƒgŒðŠ·�`

 

I would check the coils, and on another note i would put the champion plugs back!!! I have heard horror stories and have had issues myself when changing the plugs to someothing that may seem better but in the end is not! Champion only! Trust me

 

When in doubt or trying to troubleshoot an issue, go with OEM to take the variables out of the problem solving process.

I must say, though, that I've used both Champions and NGK iridium and haven't felt/seen/heard any difference whatsoever in how the engine performs. I think I have about 30k on the iridiums....no problems. I only went to them because they're supposed to be easier on the coils <shrug>

I can't explain why some have problems with alternate spark plugs and others don't....but it's something that comes up on every car forum I've ever used.

Cheers
DD

 

I don't think either that iridium plugs can cause problems.
But, in my opinion, they actually don't match to older cars like X300. I like the feeling of the normal plugs, I feel the engine with normal plugs rev up more sharply.
That might be some kind of Placebo effect, though.

 

Thank you all for your help. Changed #5 coil pack and fixed the problem. Car runs perfect again and smooth as silk. Turns out car was misfiring on #5 cylinder due to a bad coil pack, guess they go bad over time.

Glad to have unlimited resource for help, thanks everyone.

 

If you noticed doug, i never said that the spark plugs were the underlying issue, i actually stated to check the coils as i seriously doubt that spark plugs from ngk and them being iridium plugs would cause these types of issues, i merely mentioned the info on the plugs as a side note because myself, and others have noticed that the engine seems to run smoother on champions.

 

I misunderstood you posting.

You mentioned checking the coils and in the same sentence recommended changing plugs, followed with "issues", "horror stories" and an emphatic, no-room-for discussion "Champions only. Trust me".

I didn't realize your spark plug commentary was intended mererly as a modest suggestion that might make the engine run more smoothly.

Sorry.


Cheers
DD

 

Doug, no need for the apology! We are fellow members, i just wanted to make sure that what i was trying to say was understood. Furthermore, i have had friends who ran platinum and iridium plugs on their cars only to have major issues down the line with misfiring etc... I for one dont like taking chances and since everyone i know who has a jag swears by champions(Not to mention they are cheaper!) i use them too. Just my two cents. But before anything, i would always check the coils first before checking the plugs.

 

Ok so After replacing coil packs and getting accational check engine light but only on hot days. And no problems which the check engine light during the winter. I always thought like in every other car Clean the Idle Air Control Valve Vacuum/EGR its the same thing in x300s I guess, Cleaned the Tubes and the Intake, Still idles rough, I made the coil packs since i was not going to buy some useless overpriced crap online. I just cut the extra pieces off other Coil Packs from a ford, They looks the same length i just cut off their bolt on part since it was a little different. Since it was also for 3.9 4.something motor i knew they would work, except the electrical plug has to be flipped upside down because fords coils have the same 2 prong set up, just upside down, and the connector is different so i melted it off with the soldering iron. Almost doubted my self, because it still idled rough, and read endless posts this is a very common problem. SO here is the solution after 2 weeks of messing with the damn car. Which by the way i love. Its built just like i would built it. The problem is = ON the thermostat there is a thermostat temperature sensor(1Prong) and A TEMPERATURE SENDER, (2 Prongs for power )-THIS IS THE PROBLEM it sends a resistence signal to the ECU making the car run like total poop and stall on hills. I started it got it warm and disconnected it. PROBLEM solved, it runs so smooth with that thing not plugged in. It controls the amount of fuel needed and messes up the MPG. SO

I found one online using Google product search for 12 dollars down from 45$. I swear people just screw all of us because the car is a jaguar they instantly think the parts are gold. So using Google product search and cross ref-ing the parts i got it a new Fan after market because the bearing went. ALSO to all my JAGUAR buddies. When your little plastic pulley for the AC goes, dont live without AC keep the useless plastic crap part, and take it to a junk yard, locate a Lincoln Mark the 93- 2002 model it has the same exact size thread size and its 5$ not a hundred and did i mention its made out of steel so you never have to f*&^ with it ever again. I DID IT IT WORKS. my jaguar runs like a champ and i have found really cheap solutions that work better then the original.

YOUR QUITE WELCOME
PETER KIRYLUK 2 Jaguar OWNER 97 x300 and 88 XJ6, Previous Lincoln TownCar Owner until they started making air suspension garbage cars. Feel free to emailing me if you want to see how i made my coil packs from other 15$ per coil packs. It will only cost you 70 with shipping. And it works fantastic.

 

Thank you for sharing your findings and solutions. I'm a new '97 X300 owner and have been reading forums like these to keep things like this on the memory back burner just in case they come up with mine. I have some front end issues starting to develope that I am looking for help on eventually. Shimmers slightly at 70mph, and front end driver side knocks over rough road, like something's bottoming out. I see daylight through front lower shock bushings, got the parts, hope it is the resolve. Want to get the Jag Ride of Smoothness back that I believe this car had and that I've heard raves about. Owned her for about 3 weeks now. Love the car.

 

Oh man, I had this a little bit and it's getting worse.

But now that I'm looking at it, it honestly feels like I got a bad crank sensor. Because my engine will inexplicably start shaking and idling rough as heck it will will start correcting itself at higher speeds / revs.

 

Sometimes to you get codes 300 306? Or no codes ,Did you Check the temp sensor, The way to do this is, get the car running hot and i mean like HOT not getting it up to normal.
Step One, Find your Temp Sensor, it has 2 prongs, you will only notice a difference if its fully hot. Think of the temp sensor as a changing RESISTOR that constently tells you ECU Computer how much air fuel is needed to make the car run smooth and not like poop. Run it till its hot to touch the top of the motor, may take like 30 mins of idle from cold

Step 2- Pull the plug connector off while running and hot. Give it a moment and get in your car to see if you feel a difference. Remember its a resistor, so by pulling it off while its cold, it will eather still run like poop, or stall, or RPMS will go up and the gas pedal when pressed will not come down intimidatingly.

STEP 3 Now that its hot and you noticed a bit of a change with it getting smoother, no more shaking, bucking uneven motor idle. Find your self an old radio of some kind or just go to radio shack, or what ever you don't mind destroying to get the part that controls the volume.

Step 4 This Volume control slide switch or knob, should have 3 ends on it if it has more you need an ohm meter. Anyway This is called a Potenchiameter (sorry its miss spelled im Polish) gave it 7 tries still cant spell it right lol) This "Volume knob only controls ohms" Its not a voltage regulator, A switch like a light switch to your house is different, it send out too much power. The Volume switch only controls sound, and as you remember you Speakers require less power, and the Potenchiameter Volume Control Switch gives you better control over smaller amounts of power "Eg: Volume" By holding back the power or letting it thrrugh to complete a DC currant. Because yours speakers are always in a circle, they are always DC. - This is the important part" The holding back of the currant is the resistance. In a thermometer the heat makes the coil inside expand kind of like a CAR THERMOSTAT, and the amount of spring conecting with the shell is what lets the power resistance flow or not flow. Like a sink faucet, but instead of the handle you need a DC power loop.

IN YOUR CAR - The Thermostat switch is controlling the flow of power your to your ECU, by relay.
The relay with 2 DC power Loops
just has 4 prongs, or more but you need the first 4
2 for the main power 12 Volt Car Power making a loop to the Load or (ignition, Fuel Control, Idle Air control valve)
2 for the controlled Change DC power loop, making the relay switch on or off the controled sensor or what ever else that has a purpose of monetring something, it could be a photon cell it really does not matter.
THIS Power from the Temperature sensor or any other sensor, is always the same.
RESISTANCE- Power flow, much lower usually, depending on what you need it to control. THUS the need for different relay MODELS.

ANYWAY, the Temperamental SENDER SENSOR needs to change resistance like a car thermostat in your JAGUAR at all times. Making the DC power loop to your ECU"( a bunch of much smaller relays combined on a silicon panel).

This Power then passes in the circle to the first 2 prongs, < inside is a wrapped coil, which makes the power much greater, and at the same time creating a magnetic field. Like in an electric motor but, it does not rotate, instead it slaps to-gather the other side of the RELAY that go to the other 2 Prongs. This is done by a metal tongue that is not connecting to the power of the other-sides dc circle loop, but pushes a little plastic plate , (like a metal plastic sandwich, from the first half of the relay using the smaller voltage of OHMS to your Temperamental Sender Sensor.

This prosses in your x300 Controls amount of FUEL, the amount of power to the coil packs, and the amount of air the idle air control do-hicky is letting through. A very minuscule difference as the system will still be on BUT its very important for your Jaguar to idle smooth.

CHECK IT MY car started this problem at 150,000 miles. So just find one and put it in anyway to avoid the problem. This will also cause stalling when you let go off the gas and apply the breaks at intersections. The stalling and roughness IS ALWAYS going to show its ugly self, when you temperature sender is LYING to the ecu, making it do things it wouldn't normally do. A real bad influence if you ask me.

ANYWAY, you can use the volume control of anything Usually 3 prongs, your only using 2, most are going to be the rightest 2 prongs. Run a wire with 2ith 2 prongs to the TEMP sensor PLUG. And then show your wife how to drive it until you get the part.

So Volume knob turn all the way to the right MAX to COLD START,( it will NOT start if your resistance does not match the actual temperture of your motor.) YEAH THATS RIGHT READ THIS PART UNDERSTAND IT Before you start messing with the coils for no reason.

You can also tell your sensor is messed up if your car is getting less then 19.9 MPG on average living in a suburban town. You can smell it, raw gas, you can see it when you start it cold, lots of steam and raw fuel out into the world out of your pipes.

Coil packs do go, but really only when its really really hot, and the Ways to tell that is not being able to go up hills, or beyond 2000 rpms while your moving in your car or it chokes. And when its cools down its ok. again. THISCOIL pack problem can be solved, by taking all of the old crappy Lucas Garbage coils, out of your car and chucking them as far as you can throw them. You can do what it did to that, Go to ebay find Lincoln LS style coil packs, they will fit your car, you will have to cut off the screw loops with something. I pushed mine in so they are about an inch sticking out, and covered them with original cover. This design is much better because its NOT HUGGING a hot as* engine during peak summer weather. Plug design does not fit the male to female body, but it does fit the sides of the plug and the prongs perfectly just flip them upside - DOWN from yout jaguar to the Lincoln LS coil pack.

NO matter what people will tell you Jaguars are temperamental they need special really expensive 80 dollar plugs for each. Is complete non-sense. When you have a problem in your Jaguar, Call an electrition, not a mechanic. Because by the time they figure it out you will probably have paid off their house. You can get LS plugs ALL of them for 70 dollars and it works i will have to post pictures to show you guys how it works. So you can be free from the BS.

And the car runs just stronger. the coil packs from a lincoln are 3.9 and 4. something i forget but a bunch of cars use them. Stolen from the Jaguar a while ago they even have a really close plug size and all just upside down. and that is the tricky part. BUT hey for all6 i paid 70$ with shipping YOU cant beat that with a stick, https://www.jaguarforums.com/forum/i..._deadhorse.gif

Also while your getting your Lincoln plugs.

GO to the junk yard, find a Lincoln mark, with 4.6 alternator on top, locate the AC wheel, just like the little plastic wheel in your jaguar that costs a 100 dollars and buy it for 5. THE WHEEL IS metal, it has the same sized thread and same size bolt inter fitting with the JAGUAR completely and really easy to install. Just do it because the plastic crap, Jaguar put in breaks a bearing and then burns a hole in the plastic wheel and rips your AC BELT.

I can go on an on, my car runs great and its really cheap to maintain. Looks like million dollars and yet its unlike any standard model. You should see my solution for the Extra Trans Cooler/ Radiator Fan setup from the original. As the motors start to shake because once again the bearings are cheap. Anyway if you need some help, im happy to help, only on xj6's sorry haven't owned another models. Beside every single Lincoln ever made, until they made air suspension, so now i only use their parts LOL

 

Hey to the guy that thinks its a bad crank sensor. , but im better then a mechanic, i'm a Polish Inventor. I know how that sounds. I just wanted to tell you you should clean that sensor, its crudded up its right next to the fan. BUT that is not the problem. A crank sensor when bad, craps out just like temp sensor, with heat, or a puncture to the wire its self. Or the wire becomes old and since its silicon it send the signal to the motors metal housing and not all the way to the ECU. This problem will show its face only 2 ways. WAY 1, the car wont be able to start, it will spin but not start at all.

WAY 2. The car will stall out when it warms up, depending on weather temperture variables and its location on the motor to the amount of time it will allow you to drive. It stalls your car out when warmed up and then you will not be able to start it at all. Untill you wait for the sensor to cool down.

If it becomes super dirty with god knows what oil covered in its present location on your jaguar behind the fan, It will skip the metal teeth, if it would do this 2 times, The computer will shut down your car and not allow it to start once again. Untill it cools down, allong with a code but only when it stalls out.

THIS is not Plausible, because once your car is idling poorly and miss firing here if it was your crank sensor, it would just shut your car off and and you will not be able to start it.

It could be your valves, or check the cover on top of the motor, make sure oil is not leaking into the spark plug holes. make sure both your tail pipes are letting 3 cyl 3 cyl cycle out gasses correctly, if one is plugged up it would hick up. Check the Idle air control, make sure its clear, and not plugged up. Actually if your car has 150,000 130,000 miles it on just take it off and clean it. Its diffidently plugged up completely. Guaranteed, check the pipes that go to the idle air control valve, clean them up. Also Locate the Air Inlet Intake PCV styled Valve for being plugged. This IS VERY VERY important, if you don't, and its plugged up you will blow out a seal because the engine pressure is not able to escape, causing motor oil to spew out and idle like poop. Its attached to a metal squiggly tube Google it for the image.

You know what just call me 860 202 1969 text me before hand to let me know. Ill help you if you want. Ill help anyone else with the similar problem. Also read my posts they have red text u above and below https://www.jaguarforums.com/forum/i..._deadhorse.gif
your post.

 

I would advise to use precaution when disconnecting the coils while the engine is running to see what cylinder is missing because unburnt fuel is entering the CAT and will cause this to fail prematurely. I learned from experience that when it gets red its a little late.