'01 XJ8, 58k miles. Recently bought from a used car dealer, and having perused these boards I expected some issues to arise. The car has likely been sitting a lot over the last several months; only about 600 miles since Oct '18 and I'm guessing a decent chunk of that was being driven from Georgetown, TX to Houston area. The car runs well. The car is at a (thankfully very close by) Jag dealership for a once-over. My question will require conjecture on your part b/c I'm impatient and don't really want to wait for the service dept. to get back to me, hopefully tomorrow

So the situation:
1) RP after a 10-15 minute neighborhood drive, just after I put the car in park. No CEL. Engine started to knock in conjunction with the RP light. Shut off engine for a few minutes; I was at my destination anyway. When turned back on, engine purred to life and drove home just fine.
2) A few days (and uneventful trips) later (today), RP after 10 minute drive to dealer service dept (I made appt for them a few days earlier to give her the complimentary multi point inspection and check brakes), again just after I put the car in park. This time no audible engine knocking. No CEL.

Before anyone asks, I have no codes b/c my OBD2 will be arriving tomorrow. So the Jag sits at the dealer waiting for a diagnostician to check her out tomorrow. Evidently, none of the techs there today are too experienced w/ XJ8. This doesn't inspire me w/ confidence, but the advisor seemed to trust his "ringer" to diagnose her.

My question is: Based on your combined experience and knowledge w/ RP and w/out knowing any codes, what would you think is the likeliest cause of said RPs? The keys to me are 1) that RPs have only occurred upon shifting into park; 2) the knocking sound that went along w/ the first RP; and 3) the car sitting for what has perhaps been many months with the same tank of gas.

One final note: I washed her on the first night of ownership; thankfully my daughter checked under the gas flap afterwards and we found the reservoir filled with water. Gas cap was tightly sealed. I put some weed wacker line down into the drain hole and it quickly cleared up (thanks to the forum for that suggestion). The RPs occurred after said dousing, but I'm wondering if cap is completely watertight as well as airtight, as the water level was up at least close to where the cap meets the neck.

Thank you in advance for any conjecture you can muster. The help so many of you provide is really informative and educational!

 

Everytime I've had that, it was knock sensor, weak battery or throttle body codes related.

 

+1 on battery. I too have had issues with restricted performance light and abs light because of the battery whilst the car being good and having no CEL lit up. I’ve read on the forums that you can get the knock sensors really cheap from another model, they’re just a tad longer but work perfectly.

 

I had restricted performance on my dash it was the Knock sensor . if the engine refuse to rev up beyond 3k rpm then definitely it's the knock sensor there's 2 sensors it's easy to replace them.

I think the original denso sensor is about 125$ I got the standard motor products KS305 for 74$ it works fine .

 

Easy to replace on NA X308s.

 

UPDATE: Dealer says they got RP briefly when they opened up the throttle but that no fault codes were thrown on the SDD, whatever that is. I picked up the car tonight and toward the end of the 10 minute drive home, RP pops up again and doesn't go away this time. Pull into the garage and I get the same shudder I got last week. So I shut the engine and hook up my newly-bought OBD2. The code P0357 pops. I found another thread regarding this code (see below). Considering the old tank of gas that's still in the car, I'm starting to think/hope that a fresh tank will do the trick (as one or two posters mentioned). If it doesn't, I have a couple of options: 1) check out the coil myself (don't feel too confident on that one); or 2) I had already made an appointment at Momentum Jaguar a couple days ago (for next Monday) b/c I wasn't feeling great about this dealer...I've heard positive things about Momentum's service and I have a code to show them and save them some diagnosis time. If anyone has advice out there, I'd appreciate it.

EDIT: Forgot to mention that this is the same tank of gas that came with the car...only about 600 miles logged since Oct '18 so it's possible only 1 tank has been filled since it came to Houston area from Georgetown TX (about 150 miles away). I was hoping to clear out most of this tank before a refill and it's getting close...so I'll put some fresh 93 in tomorrow.

https://www.jaguarforums.com/forum/x...isfire-185618/

 

Craig, searching similar threads, they seem to find that either fresh gasoline or replacement of #7 coil pack cured the problem.

I think I would add StaBil and other gasoline additives/rejuvenators to the gas tank, and then top it up with premium gas, and then drive the car as much as possible to use up said fluids, with the intent of diluting/enhancing the existing gasoline until used, and then add new premium gasoline when the old gas has been used.

If you are unsure of the age of your battery, it may be a good idea to purchase a new one. You can buy a good quality battery from Walmart for around $120. On these cars it is a good investment. https://www.walmart.com/ip/EverStart...SABEgJQIPD_BwE

If the problem continues we can investigate the Coil pack or knock sensor path. Maybe not the problem you have, but if they are the knock sensors are easy to replace, as are the coil packs.

 

Thanks Kid, I went out tonight and bought StaBil. Will add it tomorrow when I fill the tank and take a highway drive. There's only b/w 1/8 and 1/4 tank left so really hoping this will work. I found an interesting article on how "bad" or "dirty" gas can cause a lot of detonation problems and misfires. As I mentioned in my OP, I had that water sitting near/on the fuel cap so it's very possible so of it snuck into the tank...and who knows if that happened in the past?

In addition, during my trip out tonight there was no RP...so that's a good sign.

https://www.aa1car.com/library/us10325.htm

 

B/c I suspected that some water had made its way into the gas tank, I also bought Heet Gas Dryer (didn't use StaBil) and added that to the near-empty tank before driving 1/4 mile to the gas station and putting in fresh premium. I noticed the tires were all 10 psi below specs so put it in park and left it running while I filled them. RP came on when the car went into park and stayed on. My plan was to open up the car on the highway but w/ RP I didn't want to do that, so I pulled into a lot and put it in park again, planning to shut off the engine and restart. To my surprise, the RP went OUT this time when she went into park, and I sat there for a minute dumbfounded. Took her out onto I-10 for a nice 20-mile round trip. Trip felt different with the inflated tires and engine sounded more smooth with the new gas. I'm hoping the problem doesn't show up again!

 

I have had the RP many times & was frequently an ignition coil.

If coil #6 may get these codes:
P0306 cylinder 6 misfire detected, generic code


P1314 misfire catalyst damage bank 2 engine mechanical fault


P1316 Misfire exceeds emissions



1 # changes depending on the specific coil.
1 by 1 over the past decade I have replaced 7 of the 8 coils. I'm sure in the next year I will get it again & replace that 8th coil.

It is easy. I always use genuine Jaguar coils. There are threads here with instructions on replacing the coil.

If you are unsure it is actually a bad coil, you can always swap coils.

Example. Your OBD2 says coil # 7 is bad. You switch #7 with #8 & clear codes & see if when you get the RP again it now says coil #8 is bad. That would be your proof.

Search for :
"Replace an Ignition Coil on a 99 Jaguar XK8 VDP V8"

 

Maybe bad gas (since October is an awfully long time), but I would follow up on Steve's suggestion. Pull the coil pack on # 7 (third back from the front on the left side): maybe corrosion, maybe frayed wire . . .

 

Another couple of uneventful 15 minute round-trips on evening of the 3rd, then didn't drive her yesterday. When I take her out today I'll keep an eye out for RP light. If it doesn't show up tonight, I'l cross my fingers that we're out of the woods. Hopefully the HEET and premium fuel are doing their jobs.

If the RP pops again w/ the same code, I'll take you guys up on your advice and check out the coil.

 

Here's an update on what has been going on; hopefully this will help someone with similar issues

RECAP:
Bought '01 XJ8 (58k miles) two weeks ago. Car only had about 600 miles on it from October '18 to purchase date, so it definitely had some "sitting" time in previous 8 months. 20+ miles drive home was fine. After we washed the car that night, my daughter opened the fuel filler flap on a whim. We found the reservoir around the fuel cap and neck filled with water. Used weed wacker string to clear out drain and didn't think much more other than "I really hope that fuel cap was securely placed on there!"

Next day, RP codes start to pop. After I receive the OBD tool I find that it's mostly 0354 but occasionally 0304. Fairly common occurrence for ignition coil faliure, bad spark plugs or bad battery. This continues for about a week, not on every trip but more than 50% of the time as I'm trying to work the potentially bad gas out of the system. I put dry gas in the tank at about 1/8 full and filled her w/ premium and extra additives, trying to get her some of the good stuff.
END RECAP

I replaced the air filter late last week and cleaned the MAF (though probably not well enough based on what I've read). Starting last week, I began ordering some ignition coils and spark plugs; figure that even if that's not the problem they're nice to have on hand since mine are probably OEM. On Monday, I take apart the AF box, TB air intake and clean all items as well as possible. I find some oil in the TB air intake hose, but not a huge amount. As I'm inspecting for cracks or breaks, I find an inch-long crack near where one of the clips attaches to the top of the AF box. I seal it w/ SuperGlue and put some electrical tape over the seal. It looks close to airtight.

Worried about the RP codes I got on Monday, I let the car sit overnight and take her out with trepidation on Tuesday morning. Perfect 50-mile ride, mostly highway, only a brief TRAC/ASC not available notification that came out in the last 10 seconds before I shut off the engine in my garage. Hmmm...ok. Take another 50-mile trip (again mostly highway) last night and again no codes; this time nothing else popped either. Another 50-mile trip today, this time asking a little more of the engine w/ varying speeds, acceleration, stop-and-go, etc. Again, no codes.

So that's where I stand, at about 3/8 of a tank and feeling cautiously optimistic. My plan is to work out as much of this tank as possible, put in another HEET dry gas treatment and hope that it was indeed a watery/bad gas combo that caused the RP codes to pop.

I've learned a lot from many of you on this forum, so thank you, and...

A BIG THANKS TO GLEN (CARNIVAL KID) FOR HIS HELP IN DIAGNOSING MY PROBLEMS!!!

 

First -- you don't fix cars by throwing parts at them. Coils do fail .. but, you will get the code again ... Has the code popped up again?

If this was a PAG product with very common coil issues I would say replace them. My guess is the coils/ plugs etc are fine.

The sensors on the TB have a history of causing problems -- it's the design of the system. Double fail safe -- the sensors are not available w/o buying the whole $2500 TB. If there is any dirt or flat spot on the sensors the FS or RP will pop up and the car will start to shake from running rough. This running rough will often cause all manner of codes -- it can also take a few attempts to clear them with the reader.

My advice: With the car off push the pedal to the floor 50 times -- make sure all the codes are clear and start the car. Take it for a drive to get a new battery -- the Bosch rebranded from Pep Boys is the one I use for all my euro cars. A new battery is the only thing to waste throwing at these cars. For the next two weeks -- push the pedal to the floor 30 times before you start out.

Just because the battery starts the car does not = the battery has the capacity to maintain the car voltage. Any fluctuation -- any and the FS?RP can pop up .... trust me I have been down this road.

Pulling apart a 20 year old car .. can always cause other issues. If you notice any leaks in the intake after the flow sensor -- replace the intake parts. They do crack -- the accordion part

 

Thanks for your help! Great information...
1) The only new part I've put in at this point is the air filter. I tend to agree that at least the coils are fine, and that the 0354 code wasn't actually a coil going bad.
2) I checked the battery yesterday and got 12.6v several hours after the engine had been turned off. I still need to check the voltage after starting--if it's in the 13.7-14.7v range I should be OK.
3) I tend to agree with you that the coils and plugs are fine. After replacing the AF, cleaning the MAF sensor, the air box and TB air intake hose and exterior of TB, and sealing a small crack in the AF box (after the filter but before the MAF sensor), I haven't seen any codes pop. I will return the coils but keep the plugs that are coming, as I've read that the JTIS guidance. is to replace them at 70k.

As I said in my update post from yesterday, at this point I'm cautiously optimistic that doing all the stuff I mentioned has "fixed" the RP problem for now. Whether it was watery/old gas, bad air filter, dirty air intake or MAF sensor, or a combination of all of those, I'm not sure. All I know is that I've been on 4 or 5 fairly lengthy journeys and everything has been OK. Fingers crossed...

 

Great news that you are not get the RP code after several long drives. On some occasions when one of my coils was bad I'd briefly get a RP & 15 seconds later it was OK. Then weeks or even months later I'd get the bad shaking & very rough running & the code telling me which cylinder was misfiring. No problem waiting for these symptoms to appear. Maybe months from now...if it is a coil, which it may NOT be.
You may have fixed the issue.

RE battery, when it is time to replace, consider getting an AGM battery. Also a battery maintainer, especially if you do not drive the car daily.
CTEK is excellent for battery maintaining/charging. I have CTEK MUS 4.3. They now have an updated version.(CTEK 40-206 MXS 5.0)

I had used Interstate MPT-93 after my 1st OEM battery failed & I learned that the Jaguar mechanics used that brand as a replacement. (I'm original owner of my 2000XJ8)
Used to have 85 month prorated warranty & then dropped down to only 72 months. CCA was 850.
Size:
14 ⅜ L
6 ⅞ W
6 ⅞ H

End of 2017, I found no auto parts stores carried it anymore! Anyone carrying interstate batteries wanted to sell me MTP – 49 H8. Which had only a 6 year warranty and only 730 CCA! Prices were $199 – $227 so, I would be paying more money for a lesser battery! I called the interstate battery distributor &
was told the battery MTP– 93 is in fact still available but, it is not on consignment anywhere in Phoenix it is available through a special order only.
I abandoned the idea of replacing my MTP– 93 with the same exact battery. I decided I wanted to get a new style, AGM (ABSORBED GLASS MAT) type battery after researching and finding no reason why I could not switch to this new, superior technology.
Better resistance to vibration and more/quicker Power and other advantages.
Pep Boys had a special dropping the Bosch AGM price from $219.99 to $164.99
I bought: AGM Bosch premium battery

Part #49 – 850B AGM, SKU #838838
L= 13.93”

W= 6.93”

H= 7.5”

850 CCA, 48 month warranty, Full replacement (No prorating)
Fit just fine, the extra height was a non issue since my J-hook could accommodate it.

https://batteryuniversity.com/learn/..._glass_mat_agm

 

Thx for all the battery info...checked mine again today and after about 16 hours off it read 12.5v. About 30 seconds to a minute after starting it read 14.3v. I think I'm OK there.

Re; the AGM battery, you mentioned that it's taller than normal battery. When you said J-hook, are those the two long "screws" with the metal bar between that hold down the battery? Mine's an AutoCraft Gold w/ a 6/17 sticker on the side. That's all I know about it other than the voltage reading I'm getting.

 

12.5 is well down - have a look at charts for the state of charge for your kind of battery

 

Frankly -- nothing you have done has any impact on the FS/RP. The FS/RP occurs within a set of items. MAF/MAP cleaning is "feel good" stuff. When they are bad the car will tell you -- it did not tell you. The AF will not cause it .... and the gas being bad would be constant. same with cleaning the intake

When in goes into restricted performance the engine will not rev .... it has nothing to do with the knock sensor.

The voltage when the car is running is irrelevant -- the alternator is doing it's job. Static. The battery is there to smooth out voltage. Coming into a stop - foot on brake (lights on) AC cycling -- Alternator speed changing. The output from the alternator is not constant .. the battery is there to keep it smooth. Should the voltage drop -- even for a split second -- you can have the car go into FS/RP. A weak battery can start the car and not perform this function .. the vehicles are extremely sensitive.

My point in telling you to push the pedal with the car off is to clean the sensor. By pushing the pedal you are moving the Sensors on the TB throughout the range -- wiping the contacts. Any contamination on the contact points and the car can go into fail safe. The car is using those inputs to control the engine -- the instant it can not trust the input -- Bamb. It's the throttle remember ! It uses the CAN bus. These sensors are also used for the slip control .. same with the cruise ... when the car can't trust the sensor it shuts off the ASC and drops the cruse. It uses the sensors to increase and decrease throttle response.

The OE battery was basically the same as the BMW/MB/PAG unit --made in Spain. Clear/White. Jaguar had an announcement that they were going to use Interstate and a battery supplier -- this was a long time ago. My memory was this was in addition to the normal -- maybe they had some issues. I'm not sure it was country wide -- but, Interstate was a proper battery that could be installed by the dealer. Exide and Bosch entered into an agreement back in 08 -- Pep Boys sell them. I have them in my MB's and Porsche. The proper replacement is 850CCA -- has the vent. It's a good battery.

Because the FS/RP is so intermittent -- it can be impossible to figure out what's causing it. Any voltage or input irregularity on a critical system can cause it -- throughout the CAN bus. I have had the ACC start to beep? People are always saying: "I did this" ... "I did that" .. and it did not come back for 3 months ... 6 months. They never found the problem and fixed something that did not need fixing.

You did not fix your cars problem -- it just has not come up again. Try and clean the contacts ... and get a new battery. They go on sale all the time ($20 off)-- and Bosch or Pep Boys often run some rebate.

Also: The fuel pumps on these cars tend to go as they age. They are in the tank (XJR has 2). If you have a long crank situation .. or feel a slight stumble at speed ... that's where to look. Again -- this is anther item that will not give you a code .... and people start replacing plugs/coils .. you get the idea. When something fails .. it's usually easy to pinpoint. A dead fuel pump can only be a couple of things -- The pump, relay or no power. When the pump works most of the time .... can be very hard to figure out unless you understand that these cars have an issue with the pump. That's why people are directing you to the battery ..... and I'm telling you about the sensor cleaning

 

Yes, Those long "screws" are called J Hooks. (I had to look it up when I was checking to see if the AGM battery I was thinking of buying would fit w/o having to buy new, longer J hook.)

IDK if your battery is Good or not. I mentioned the AGM in case you decided you need to replace the battery, I think AGM is better vs. old style wet lead-acid.
I would NOT replace a battery unless I KNEW it was bad or marginal. ( May need to do a load test, some auto part stores will do this for you @ N/C Most of us do not own a battery load tester)
If you do not already have a battery maintainer (I like CTEK) Good idea to get one.
From my CTEK manual:
MUS 4.3 (1065) is a switch mode charger with both float and pulse maintenance and is a part of a series of battery chargers from CTEK Sweden AB. These chargers represent the latest technology within battery charging. A MUS 4.3 (1065) gives the battery maximum life.

It does more than just charge the battery:
STEP 1 DESULFATION

Detects sulfated batteries. Pulsing current and voltage, removes sulfate from the lead plates of the battery restoring the battery capacity.

STEP 2 SOFT START

Tests if the battery can accept charge. This step prevents that charging proceeds with a defect battery.

STEP 3 BULK

Charging with maximum current until approximately 80% battery capacity.

STEP 4 ABSORPTION

Charging with declining current to maximize up to 100% battery capacity.

STEP 5 ANALYSE

Tests if the battery can hold charge. Batteries that can not hold charge may need to be replaced.

STEP 6 RECOND

Choose the Recond program to add the Recond step to the


charging process. During the Recond step voltage increases to create controlled gassing in the battery. Gassing mixes the battery acid and gives back energy to the battery.
STEP 7 FLOAT

Maintaining the battery voltage at maximum level by provid- ing a constant voltage charge.




STEP 8 PULSE

Maintaining the battery at 95–100% capacity. The charger monitors the battery voltage and gives a pulse when neces- sary to keep the battery fully charged.

================================================== ================================================== ============

I think the newer model is: CTEK 40-206 MXS 5.0

================================================== ================================================== ============

I assume you are using a multimeter to measure the battery voltage at the battery.



Keep in mind that when you open the trunk to access the battery, the trunk lights turn on, which will decrease your voltage slightly. So if you are reading 12.5 V, it is actually higher.

My chart says 12.5 = 90% charged & 12.7 = 100%.


But you may actually be @ 100%.


After a drive you could open trunk & leave it open till the timer shuts off those trunk lights & then ck the battery voltage. I'm not sure how much drain results from the lights being left on, LOL.

14.3 Volts, when car is running should indicate the alternator is charging the battery just fine according to the chart I have.
12.6V Red/bad
13.1V Yellow
13.3& 14.4V Green/good
15.0 Yellow & 16.0V Red/bad


I don't have an assistant to help when I check so I bought this years ago:




<$20 Amazon

• Easily plugs into vehicle’s cigarette lighter or power receptacle to monitor battery and charging system voltage
• Designed for 12-volt negative ground systems
• LCD displays measured voltage with a bar graph to indicate battery charge level
• Color-coded LEDs quickly identify battery’s charge status
• Head pivots for easy viewing and angle adjustment

Instructions say to test alternator to wait till car reaches operating temperature & then Rev to 2500 RPM & hold. Then read the charging voltage off the display.