Today was a normal, dry, 61 degree day in Vegas...I took my car to run errands. After my 3rd stop (car had been sitting for 15min) I started it up and immediately got a very rough idle.
I plugged in my OBDII and pulled P0300, P0301, P0302, P0304, P1313, P1316.

Revving above 2000 RPM smoothed it out, so I made the call to drive it 1.5 miles home. The car ran smoothly with no, I mean ZERO, misfires until I came to stop signs and a stop light. I let the car cool down for about 5 hours, came back to start it up and it still misfires at idle, but a little less violently.

Since the fail codes are all on BANK 1, I am leaning towards a Crankshaft Position Sensor failure...even though I didn't get that specific code P1313 looks close. It looks impossible to replace under that supercharger...but I was able to see that the connector is caked with grease and oil. I'll start by cleaning the connector, but if that doesn't work...I'll need some real help here guys.

 

Welcome to the forums copterclint,

Your post was automatically locked for moderation. I can see no problem with the content and have unlocked it. Other members will now be able to View and Reply.

Graham

 

Is this a 4.0? Could it have jumped timing?

If maybe, be wary about running the engine again at all!

If not, maybe see if the fuel trims reveal anything.

 

Welcome to the forum.

My personal experience is that oil in the spark plugs can cause misfire in the X100. Easy to check by removing spark plugs and fix it by fitting new cam cover sealing gaskets which are cheap. IMHO the spark plug seals in the plastic cam cover seem a bit “twee” for such an important job.

You don’t mention any maintenance history and whether you’re handy with a wrench.

As you have OBD2 codes, for bad idle, the TPS would also be something else I would look at.

 

Well...today I got to work and some interesting things happened. I located the Crankshaft Position Sensor for Bank 1 and the connector was covered in grease and dirt. I started by cleaning that with some CDC electrical cleaner that is safe for plastic and rubber. After it dried, I put it back together and some codes went away. At this point I was left with a P0301 and P1316.
I started by swapping a good coil pack from Cylinder 3 with Cylinder 1. The problem stayed on Cylinder 1. No coil pack problem.
The spark plug looked fine, not a drop of oil anywhere on the coil or plug. I bought a new spark plug anyway, gapped it, and the problem stayed on Cylinder 1.
I also inspected all the wires leading to the coil connectors, as some people have found bare or loose wires...no luck. Connections are tight and no melted insulation.
I was able to pull my long term fuel trims on Bank 1 and Bank 2, but that's all that my humble little Torque Pro App would give me.
Bank 1 LT Fuel Trim: Between 5.47% and 6.25%
Bank 2 LT Fuel Trim: Between 9.38% and 12.5%
I can see that I'm getting about half of the fuel trim in Bank 1, as compared to Bank 2...but I'm not sure what that might indicate. I'll dig around on the forum some more for Fuel Trim info, but if anyone has any other ideas, I'm all ears until Monday when I take it to a shop.

 

Thanks for the reply, JagV8! It is a 4.0! At first I thought it might have been the timing chain as well...but it seemed strange that it smoothed out at higher revs if that was the case. I have had timing chains go before on other vehicles and it never smooths out.

 

Thanks DavidYau! I added an update as you were posting this to me...so I'm sure you didn't see it yet. But the spark plug, coil pack, and well were perfectly dry. I haven't had the car for very long and it only has 65k on it. I'm fairly handy with a wrench and don't mind hunting around a bit to troubleshoot. Is it possible that a faulty TPS would just cause 1 cylinder to misfire?
I'm thinking since it is the furthest cylinder in the bank, I should try to check my fuel pressure to ensure I don't have a bad fuel pump(s) or a clogged fuel filter.
Hopefully it isn't bad compression.

 

Geez! You’re working through this.

Not coil pack, not wire harness. Did you confirm you get a spark? Do you hear any strange noises?

How about blocked injectors? Can you check the pressure at the fuel rail as it is the most forward cylinder.

 

Have you checked that both your fuel pumps are working...
Failing fuel pumps can cause misfire's etc.
May not be your issue, but it was for my 2001 xkr.

Your fuel trims are not to bad, bank 1 is much better than bank 2 (bank 2 is a bit high)..

 

I'll definitely get a gauge tomorrow and start testing. I also saw your reply to someone about building a jumpwire to test the pumps through the relays...I'll take that advice too. Thanks XKR-DAY, I'll let you know what I find.

 

Irrespective of whether or not this is the cause of your problem, you need to check whether you have the updated tensioners and chain guides or if the car still has the original plastic ones. The changeover date was August 2001, so if your engine was built after this date, you should be ok. The only way to be sure is to remove one of the cam covers and have a look - or play Russian roulette every time you start the car.

At the very least you should change the secondary tensioners to the latest spec versions if they are plastic. This is the definitive thread on the topic:-

https://www.jaguarforums.com/forum/x...ics-how-52653/

 

Today I planned on starting by checking my fuel pressure at the fuel rail. Lo and behold, there is a lovely little coolant hose blocking a direct path to the schrader valve, I breathed on it and it broke. I took the car from driveable to undriveable in a single bound. New plan for the day: Splice the Hose! After some careful thought, I decided to buy a 220 degree heat shrink with adhesive inside. It worked...for now...and replacement of that hose (and every other hose) is now a top priority. At least its driveable and I can get it to the shop if need be.
I finally got the gauge on the schrader valve I got 45psi upon switching the ignition on and it held pressure. I started it up, 40psi. It held pressure. I shut the engine off...it held pressure. Not sure if 40psi is low enough to cause a misfire on cylinder one...but I'm thinking probably not fuel pump.
I also did the screwdriver stethoscope trick on my injectors and got consistent clicking on every cylinder (even my problem cylinder).
Conclusion: It is not spark plugs, coil, injector, fuel pressure loss, or timing chain.
On the to-do list tomorrow: 1. Check the coil plug connector with multi-meter for broken wires that I might not be able to see on the harness 2. Compression test the cylinder 3. Check for spark
If anyone has any suggestions on checking for spark...that would be helpful. I don't have a test light, but I could get one if I need it.

 

I'm determined to get my baby back to purring! I didn't confirm spark yet, but I may pick up a test light tomorrow before I get back under the hood. The only noises are the dull misfire and since the car is still new to me I'm not sure if the supercharger is supposed to be making noise at idle, but there's a sound there almost like a bearing that has gone bad. I believe I'm getting good injection and ran Techron through the system about 500 miles ago on a full tank. The pressure at the fuel rail was 45psi when I clicked ignition to on, 40psi when running and it held pressure in all conditions including shutdown. Thanks for the help David!

 

Great advice! I'm very impressed and even more grateful for the depth of knowledge I'm finding here. Thanks for chiming in with posts like this Dibbit to let newbies like me know what to look out for and switch out to avoid a catastrophic event! It is much appreciated.

 

I finally got to the compression test today...60psi on the bad cylinder. My heart sank. If anyone, has some ideas of how to proceed, I'm all ears.

I have been researching problems with low compression and saw a post that someone had with a low compression as well, and it turned out to be a bad hydraulic lifter. Has anyone had any experience with low compression in these 4.0 V8's? My searches aren't turning up much. Thanks to all who have helped me track to this point.

 

Copterclint,

Bugger! What's the mileage on your 2001 XKR?

That low compression value is bad news! Did you check the other cylinders? How does the bad cylinder's 60 psi compare with the other cylinders? Did you do both dry and wet test runs (ie put tea spoon of oil down the bores). Wet results should be higher.

Could be bad piston rings, bad valves and/or valve seats, worn engine wall cylinders, leaking head etc. None of these are going to be easy fixes and will need an engine tear down. I feel for you. Probably cheaper and easier to source a replacement engine. Finding a rebuilt AJ-V8 shouldn't be difficult in LA.

When I run into problems of this scale, I normally get a professional garage to double check my diagnosis before I decide how to proceed.

I've previously had to replace an engine on a 1970 Triumph GT6 as the follow up Air Leak Down test showed problems everywhere and my local Indy mechanic said the original engine wasn't worth saving.

 

Have you checked your tensioners yet? All the symptoms point to the timing chain - you really need to eliminate this before going any further.

 

What he said ^^^^. Problems on one whole bank point to timing chain since each is common to a bank. It's possible you've only jumped a tooth and not had valve to piston contact - yet.

 

One of the things you need to get a compression test with good readings is air. So did you have the throttle body butterfly propped open when making the test. If not, you only compressed the air that was in the cylinder, so not a true test. Might I add the throttle is controlled by the TPS so not moving like older cars.
Sounds like you know what you are doing, just sometimes we forget.

 

It would really help all of us if you would tell us how many miles are on the car!