One evening when beginning a ride home I received a flashing yellow engine light with a “Restricted Performance” trouble light.

I wasn’t far from home so I got myself there and parked the car.
OBDII showed codes P0308 (misfire cylinder 8) and P1314 (catalytic damage). So I let her sit and drove my other car until I could get her right.
Research here and online indicated the most likely issue was either coil packs or spark plugs. “Misfire” could be several things and “Catalytic Damage” meant raw gasoline was detected passing into the converter (so probably potential for damage if I kept driving her, but I parked her. So I think we are good).

Found these videos by Vance and followed them to replace the plugs and the coil packs.
Part 1
Part 2

Actually not that hard really. If you throw these codes, and are kind’ve handy, I say use the video and go for it. You might have the same luck I did.

I just hit 90k miles. Plugs were obviously the original set (bought the car used).

Replacement of all plugs (Bosch Iridium) and coil packs (Spectra Premium from Rock Auto) resolved the slight wobble-idle that seemed to come and go on occasion. I cleared the codes and they have not returned. She runs like a beast again.

Note:
Found a bit of oil in about 6/8 plug wells, but not enough to go replacing gaskets just yet. None seemed to be below the threads and the car doesn’t smoke at all (except for a few seconds after the job. A little Oil from the well dripped into the cylinder through the spark plug opening during the change. This was quickly burned off during first post-job start and she was back to normal exhaust in a few seconds).

A conversation with my awesome mechanic confirmed no critical need regarding the minimal oil in the plug wells, and a high five for knowing not to use anti-seize on the plugs lol

Many thanks to Vance for the great video!

Drove to work two days ago, back home, then yesterday across town and stayed the night. Woke up this morning to a request for my keys to move my car. Someone was blocked in and needed out. Handed over keys, they moved the car and returned the keys. No problem.

Woke up later and went to leave. Battery was dead.
Sigh. Asked and the car started and ran fine this morning during the move. I got a jump and she started right up. All seemed well.
But on the way home upon highway first acceleration I felt the misfire and got a flashing yellow engine light. No codes, but misfired all the way home with the same flashing engine light when I accelerated using higher rpm. Obviously a power loss, and wobble idle at stop lights.
Considering the above post, And the perfect running after the fix, I’m thinking the coils and spark plugs are not the issue.

Thoughts:

1. Someone probably left my door partially open and drained my battery. Could the battery cause this?
2. Wiring on coil plugs was “crunchy” when I manipulated them during the coil change. Could wires at coil connection be the problem?
3. There was some oil found in several of the spark plug wells, and the new coils were slightly shorter than the old ones. Could this allow oil to get in there and cause a misfire?

Anyone have any thoughts?
Thanks, and happy new year!

I have heard many times these cars are super sensitive to battery problems. This battery is not that old, and the car sat in chilly weather for a week before the coil/plug fix. She needed a jump at that point, and in my assuming all was well I likely never really got the battery fully charged again.
I will happily try recharging first.
Almost picked up a charger with only 8amps, but caught my mistake and purchased a charger/jump unit that has 10amp charging. Connected it to the batters and the meter initially showed 50% charge, then over about a min the meter went up to about 70-75% before stopping. The battery is now charging, will advise.

Thanks!

Thanks for humoring me. No guarantee the low battery charge is the root cause, but it's something simple that needs to be ruled out first.

Almost forgot, you had mentioned some oil in the spark plug wells. Did you clean that out before reinstalling the coils? If it's just a little bit of oil, you're probably okay to keep an eye on it after cleaning. If you've got a lot of oil, you'll need to replace the valve cover seals. Make sure you clean inside the boots of the coils, too. Electronic spray cleaner (NOT brake cleaner) works well.

Per suggestion, I purchased an appropriate battery charger and after several hours the battery was showing full charge.
Started her up and immediately the misfire was present. After idle warmup I received two codes:
P0301 (Misfire cyl1) and P0316 (Misfire detected at startup).

Assuming the car damage code would soon follow I shut her off. Reconnected the bat charger (why not) and the battery showed 50% charge. Set charger to recharge, and began research.

My thoughts:
1. Will check wiring for coil pack, looking for wiring/connection problem. Diagnosis by swapping known good parts, etc. Hopefully the code will follow me around and reveal the problem item.
2. Will check spark plug well for oil, and will clean out as needed. (I actually did not clean the wells out when I changed the plugs. Mistake noted lol)
3. Previous “misfire” was cyl 8, now cyl 1. These are consecutive in the firing order, and the sensor looks for power pulses on the driveshaft. That can’t be easy lol...
So perhaps this is the same problem manifesting with two different codes?

Will advise.
Any thoughts or advice is always appreciated, so let me know what you think.

Thanks!

Was that second code P1316 instead? I'm not seeing any P0316 in any of the OBD reference documents:

JagRepair.com - Jaguar Repair Information Resource


What year is your car? I want to make sure we are looking at the correct document. Also, don't trust any generic code definitions your scanner may show, such as "misfire detected at startup". Always go with the Jaguar-specific definition for the numeric code.

I think you are on the right track. Definitely clean up the oil from the spark plug wells and on the coil boots. That alone will cause a misfire from a perfectly good plug or coil.



I'm a little concerned that your battery was only showing a 50% charge immediately after running. You've mentioned you had to jump start the engine twice. It's very tough on a battery when it gets run down that far, and it's happened more than once. A voltage reading is only a rough approximation of battery charge, so don't read too much into this. However, in my limited experience, a voltage-based state-of-charge indication tends to falsely read high. I might expect to see a false 100% indication right after shutting off the engine, but instead you're showing much lower. So one more thing to humor me, please make sure your charging system is up to snuff. On a 2003+ model, you should see approximately 14.5V at the battery right after engine start, settling down to 13.5V after a few minutes. On a 1999-2002 model, you should see around 13.5V anytime the engine is running.

Yes the code was P1316, I mistyped p0316. Apologies.
My car is 2003 S-Type R 4.2L V8 (Supercharged).
I will get my multimeter and advise regarding the running post-startup voltage, however this will hold secondary priority to cleaning up the oil that may be present and checking the wiring for loose coil plugs or cracked insulation.

The gaskets obviously needs changed because there is oil present in the wells. So that is on the to-do list, waiting on warmer weather. It’s cooold here and I have no garage :/

Also in the shopping cart is the i930 OBD scanner tool.

It was warmer today, so... update:

Pulled and swapped coils cyl 1-2,
Read codes: p0300, p1316

Pulled coils off 1-2, pulled plugs from 1-2.
Paid special attn to ensure I kept track of which item came from which cyl.

Plugs may not have been tightened properly, as there was a little oil in the wells, oil on the treads and the plugs seemed to break loose easily when I removed them.

My thoughts right then: maybe caused compression problem.

• Cleaned everything including plugs, coils and wells.
• Matched the plug/coil pairs back to original pairs,
• Swapped coil/plug combos between cyl 1-2.

Now coil/plug originally on cyl 1 was on cyl 2, and cyl 2 combo was on cyl 1. Ensures plugs were tightened better.

P0303, P1316. 🤦🏻*♂️

Removed coil and plug from cyl 3, plug came loose easily, oil in well and on threads. Cleaned, replaced, tightening etc.

Removed coil from cyl 4, ensured plug was tight, reassembled cyl 4.

P0303, p1316

Slightly rough idle, obviously still a misfire happening. Hmm...

Decided to start testing things by unplugging coil packs while the engine was running.

When I unplugged:

Coil 3- marked negative change in idle. Plugging back in resolved marked change. Despite the code, this cyl was working.

Coil 2- No change in existing rough idle. This Appeared to be the misfiring cyl.

Coil 1- marked negative change in idle.

Looks like cyl 2 is the misfire, and if you remember... I had switched the coil/plug combo from cyl 1 and 2. So this misfiring assembly was originally from cyl 1, where this trouble all started.

Swapped coils only between cyl 1-2 and now the plug-test showed cyl 1 was the misfire.

The newly purchased and installed cyl 1 coil was bad.

Looks like someone may have been right about my new coil pack being defective. High five!

Picked up a new coil, installed it, cleared codes and started the car.

P1000 but smooth idle.

Test drive went well, including highway run that reached 5500+ rpm and 100+ mph.

No engine light.

Returned home, scanned for codes:
P1000, p456. (Oh you Asshole lol)

Fidget With has cap, cleared codes. Restart.

Pesky p1000. Smooth Idle.

So now, I’m considering her fixed unless and until she throws me a code or a symptom I can address :)

To humor a friend... I Tested running voltage at battery: 13.84v

She sat for a week in the chilly weather, so when I started this job she wouldn’t turn over. I put the 10amp charger on her and charged while I was working. In the end the battery was fully charged and starting her multiple times without driving when I was doing the diagnostic work on the coil packs.

So I feel like the battery is fine, and the running voltage I checked seems ok.

Occam‘s razor would say the battery was dead before bc my lady friend didn’t get a door closed properly when she moved the car that morning.

But we shall see if anything develops.

Thank you all for your input and help.

I hope I can contribute to this forum in the future, as you all have :)

Yeah, I knew I was looking for the p1111. So that’s why I’m calling the p1000 pesky. Because I don’t know where to start looking for the problem stopping the OBD Systems Readiness Test From completing.

Let’s just hope the p1111 shows up and that bridge doesn’t need crossed :)

Still working on getting the better code reader.

Meanwhile, replacing the faulty coil seems to only be a temporary fix. Sitting in line at the car wash this evening, she suddenly started that familiar misfire wobble. No codes.
But I knew better. Drove home immediately and P0302. P1316.
Seriously?!?

Tried the “unplug the coil” test to see if I could confirm it was cyl 2 but everything seemed to manifest the desired obvious negative change in idle. When unplugged, nothing remained unchanged to indicate a definite cyl diagnosis.

Swapped suspect cyl 2 coil with cyl 1 coil: P0302, P1316
Removed cyl1-2 coils and plugs.
Put coils back but swapped plugs: P0302, P1316

Un-plug test and still can’t be sure.
Both spark plugs were in tight and came out clean, looking like twins.
Maybe one drop of oil in cyl 1 plug well.
Plug/clips for coils did not show any signs of split wires or fouling.

My thoughts:
1. Injector? While the P1316 code implies raw fuel moving through the converter, Not 15 min before the problem developed I filled up the tank from almost empty with premium from a Kroger gas station. Could mediocre gas in 32 degree weather clog an injector that wasn’t cared for too well by a previous owner?
How do I diagnose a fuel injector?
2. Please don’t tell me I threw a piston ring on cyl 2.

First thing, check the pressure at the fuel rail. Use a mechanical gauge, versus just relying on what the scanner thinks is there.

After that, for a suspect injector narrowed down to one cylinder: Swap the suspect injector with one from a known-good cylinder. Don't make any other changes at the same time.

See if the fault follows the suspect injector. If so, the injector is bad. If the fault stays at the same cylinder, and you've already swapped the plug and coil with known-good components, it's probably time for a compression test.

Will do.
Any videos out there showing what I need to do to access the fuel rail and the injectors?
I don’t want to just start taking stuff apart if there is some decent reference material on doing the job.

I checked with the local auto parts store and they have loaner tools including a fuel injector tester and the fuel rail pressure gauge. Looking to get into it :)