I'm getting back to the car tomorrow and I'll try every suggestion I've gotten.

 

Sorry for no posts. I have been away for a couple of weeks in Florida. Back now and trying to get this car running. Just thought I would mention that the engine wiring harness has been replaced with no change in the problem. there is no oil in the spark plug wells. I need to check the wiring from the ECU to the plug that the wiring harness is connected to. Some of you have mentioned that 02 sensors could be part of the problem. Wouldn't a problem with the 02 sensors through a code? I got a noid tester which I will try this week although I don't think the problem is fuel related.

I can't believe that I've taken this car apart and put it back together to have this problem show up out of the blue.

 

HI Everyone. I'm bringing this thread back from the dead. The car is still not working and I am really not sure what to do next. I don't want to repeat myself with all that has been done, so I'll try to shrink the explanation. Also of note, I brought the car to a well recognized foreign car shop and they thought the problem was wiring but couldn't pinpoint it.

Changed all coils when taking the car out of storage in April. Car was running ok before but at 120,000 miles I thought it a good Idea to swap them out. I got a set of coils from China. Started the car up and it idled roughly. Scanner showed cylinder 3, 5, and 8 coil problem, P0353, P0355, and P0358. Ok, i put in the old Denso coils back in those three cylinders. Same problem. Here is a list of what I've done to this point.

1. New Coils
2. New plugs
3. (new) engine and ECM wiring harness from the salvage yard. Pin tested all wires for continuity using the Jag wiring guide. Everything checks correctly
4. Computer replaced from Foreign Auto Computers. I did this because even before this problem, I would get strange intermittent problems. The car would run rough for 5 seconds and would throw a restricted performance message. It would always clear up in around 5 seconds and then run fine for weeks.
5. I went through every ground point on the car and took the wires of, cleaned the contact point, and reinstalled the ground wires. They were all pretty clean.

After all of this, the same problem three cylinders not working. While the engine is running, if I unplug one of the bad cylinder coils there would be no change in the engine idle. Unplug and good one and the engine would idle rougher.

I'm not sure where to go next. The wiring has been checked and double checked. Swapping the coils from the bad cylinders to good ones show the coils are good as the swapped coil works fine in another cylinder. Also, the spark plug wells are bone dry and clean.

HELP

 

IF three specific cylinders are not working, it's either spark or fuel in those pots. If you remove the plugs, do they spark at the right time? If you can't read the trims and it's not in closed loop, It's got to be a fuel metering issue, ie MAF or air fuel 14.7:1, again you should be able to check this on Torque Pro. The pumps on these early cars die at the drop of a hat, and leaving the car usually does it. The pump should be giving 55 psi for a start which you should be able to read on your torque pro. There is a relief valve attached to the pump which can be faulty, 22psi is too low. Hope this helps.

 

Hi John,

Sorry to hear you are still dealing with this. Just to rule out problems with both the new and old coils, what happens if you swap the coils in the problem cylinders with coils from working cylinders? Do the codes remain at cylinders 3, 5 and 8?

Did you ever remove the wrapping from the coil wiring harness to inspect for damaged wiring as WhiteHat recommended?

Have you tested at each coil connector for supply voltage on the Red/White wires when the key is in position II (ON)? You should also have very low resistance to ground on the Black wire at each coil connector.

It might also be worth checking for good battery voltage at pin 3 of the ignition coil relay socket, for good engine-managment switched voltage at pin 1 (ignition ON), and for very low resistance from pin 2 to a good engine compartment ground such as the engine management ground point on the right inner fender.

If you don't already have it, you can download the Electrical Guide here:

Jaguar X100 Electrical Guide 2000

Are any other codes stored in addition to the P035X ones? Even if you don't think they're related, please post them here.

Cheers,

Don

 

I wonder...
Are your issues similar to those that prompted you to replace the ECM?

Perhaps the swop introduced something new into the equation. Do you still have the original module that you can swop back to see if the symptoms change?

 

Well I have some interesting news. I picked up a coil tester because I can't believe there's no spark on those cylinders. I hooked it up to cylinder E because it's the easiest of them to get to. Started the car up and it showed good spark. I unhooked it and decided to go watch the football game while deciding what next to do. MikeAlford mentioned that it could be a possible fuel problem. I did check the fuel pressure months ago and got 38psi at idle and upper 20's when giving it gas. I decided to see if I could check the fuel trim with Torque but I can't find my ELM adaptor

I decided to use my regular scanner and read the live data. Hooked it up and started the car. It idled perfectly!!!!! I'm now shaking my head. What's going on here. I let it warm up and then took it for a 15 mile drive not getting too far from home, just in case. The car ran perfectly.

Now my question to all of you brains in this forum, is it possible I have a dodgy fuel pump that just decided to work? My scanner showed closed loop on the fuel system and the fuel trims were good, between -3 and +4 at idle and around 9 when giving it some throttle. Any thoughts would be welcome. I'm not going to trust the car until I figure out what was causing the problem. Just wondering it the codes sent me down a wild goose chase when the coils and spark was fine.

 

Well the MAF is working, so that's good, the trims are good so the injectors are good, and if you've got good spark then however improbable, what's left has to be the pump? The later cars have a different fuel system, but early cars have two fuel pumps, and very often one has already failed before the owner notices, and then the remaining pump becomes flakey. There is a video about investigating, and shows a relief valve made of plastic attached to the pump, which can crack and split lowing the pressure. If the pressure drops, then how many cylinders can it reach before it runs dry?
I no expert, but logically I think you should check the pumps since logically one must of already failed? Keep your coil tester handy in case your car plays up again, and if the spark is still good, then you know where to look.

Good luck, I believe logic and reason are more important that just reading codes, however helpful codes can only give unthinking clues, which are just part of the puzzle. But perhaps because I was a software developer, I understand more than most. You've done very well sticking on task, no matter how frustrating, you will be rewarded at the end of the day with the solution.

 

Only the 4.0 XKR has 2 fuel pumps. Your 2000 XK8 has only one. If you suspect the fuel pump is on sort of edge, try some reputable fuel system cleaner. We seem to hear a lot of good from Techron. Use the appropriate quantity as per the bottle, more is not better (makes the rubber parts swell). Maybe running one or 2 tanks with the additive will help. FWIW, I would not keep a tank with this additive sitting the whole winter, but check what the bottle says.

For the fuel pressure reading, remember the car is operated with a constant fuel pressure as compared to the intake manifold, not the atmosphere we live in. So, as you mess with the throttle, a fuel pressure reading from a gauge will definitely change, and should read the lowest at idle (high manifold vacuum). As a test, you can remove (and plug!) the vacuum line to the regulator to see what the reading is (it should no longer fluctuate with the throttle).

Best of luck, keep us posted.

 

+1 on the Techron. Checking their website, it does not stabilize the fuel, so I would not leave it in there long term. I'm pretty sure that used to be different, but I guess I was mistaken!

Might be worth changing the fuel filter, which is cheap and easy, just in case.

If the misfires recur, swap the injectors around and see if the misfires move. If they do, then you can either get replacement injectors (expensive) or get the existing ones refurbished (cheap, but takes longer).

 

Hi All, Current situation. I took the car out for a drive today with my code reader on viewing live data. I drove about 10 miles with 4 of them on the highway. Car is running great. Get of the highway and at the stoplight it starts running rough and restricted performance shows up. I just happened to have the scanner on the fuel system page (which was showing CL) and as I looked down it went from CL to ERROR. I pulled into a gas station about 100 yards away and as I parked, the car smoothed out and the ERROR on the scanner changed back to CL. It ran fine from there to home about 3 miles. No check engine light or codes.

Just a note. I run Techron in the fuel tank twice a year. Fuel filter was replaced about 10,000 miles ago. Fuel injectors were cleaned and serviced by RXinjectors about 4 years ago.

 

Update time. I made a decision to replace the fuel pump. I think the problem is fuel related and not wiring. I figured the fuel pump is the cheapest thing to start with. If not, then the injectors. Yesterday the car had a little under a full tank and I wanted to run it down to around 1/4 to replace the pump. I drove the car for almost 3 hours within a 10 mile radius of my house and it drove perfectly the entire time. I got a fuel pump at Napa and today set about the task of replacing it. The hardest part of the job was getting the tank back in. I've only driven it to the gas station after the pump replacement so I have not idea if this has fixed the problem. The car started right up.

My plan is to drive it as much as possible in the next few days and just see how it behaves. I will not drive with my wife because she would not be appreciative of it messing up and having to be towed home. I will keep you all informed.

 

One week update. I've put around 200 miles on the car since replacing the fuel pump. At this point, it's running perfectly. If it doesn't snow, I'll keep driving it until I'm secure that it's fixed.

 

Well done....

 

John, I had to laugh as you made removing and replacing the fuel tank, so matter of factly, no grunt or groans. Just a little trouble getting it back in.
Really!!! Are you Plastic-man to reach around all that's in the way. LOL
Pulling your chain mate, so glad you not only got it fixed but you let everyone know some of the things to look for when it's our turn.
Thanks.,

 

John55,

Well done and thanks for updating this thread which gives me, and others, some idea of warning signs/symptoms to look out for.

I admire your persistence and patience as you started having this problem way back in May, and finally fixed it 6 months later. +1 to Wayne, as to me, as a humble amateur home DIY mechanic, you're simply "very matter of fact" on tasks/jobs that:
1. Scare me - changing ECM
2. Make me pause for a breath - changing coils
3. Plan my attack - changing plugs
4. reach for the Workshop Manual - checking pin continuity from ECU to wiring harnesses
5. Go "gold digging" on this Forum for guidance/tips - Checking electrical ground points for car
6. check if Rev. Sam (aka sam1174) has a You Tube Video - ripping out fuel tank to change to change fuel pumps

You've gone through all the above, and found out that the DTCs given were just symptoms of a ground zero problem, and the fixing the DTCs did not resolve the source issue. Marvin recently said "Why do our cars outright lie to us"...…. Nuff said.

 

Why do our cars lie to us? That is so right. I had the car stumble and give a restricted performance once and then clear up and drive perfectly for a 40 mile trip yesterday. At this point, I feel like I could take this car apart and put it back together in an hour I'm going to change out the 3 fuel injectors in the suspect cylinders. Unfortunately, the weather has turned here and it's snowing. Not sure if I'll be taking the car back out on the road for the winter. We'll see. Thanks to everyone for the help. I forgot how much I love this car until I got it back on the road at the end of the season. Now it's snowing

 

Well I have a resolved update. It's embarrassing, stupid, and sadly satisfying. If you've read this thread, you would know that after taking my XK8 out from it's winter sleep two years ago, I decided to put new coils. Did the job and started the car and got a very rough idle with codes showing 3 cylinders having coil problems plus misfires. I tried everything including:
1. New spark plugs
2. Replace wiring loom
3. New ECU
4. New fuel injectors
5. New fuel pump

After each fix the car would still show the same problem. One day out of the blue the car started up and ran perfectly. I drove it for around 100 miles with no problems. The next day I take out for a spin close to home and about one mile from home it starts to sputter and gives me the same codes as before.

I started thinking that there must be a timing problems. What the hell else could it be. I haven't been able to really drive the car for almost two years. I decided about 3 weeks ago to take the cam covers off and check for timing or chain problems. I take the covers off and lined up the flats on the cam. Perfect. Now I'm frustrated because a timing or chain issue was my last resort. Using a flashlight I checked down the primary chain to see if I can spot any problem. Low and behold I find the problem. It's so embarrassing that it hurts me to say it.

When I replaced the secondary tensioners I left the pin in the passenger side tensioner. The car ran fine for three years with the pin in there. It seems when I started the car two years ago, the pin moved and was not allowing the tensioner to work correctly which probably gave the chain too much slack and presenting me with poor idle and codes. I removed the pin, replaced the cover with new gaskets. I have now been driving the car for three weeks and it runs perfectly.

When I found the pin stuck in the tensioner and showed my wife, she said, YOU KNUCKLEHEAD

 

are you serious... that was the roller coaster ride read of the day... glad the car is running well now~

 

I'm sorry you had to go through all that. What an ordeal. But you were man enough to fess up and maybe someone else won't do the same when they remember this story. Thanks for sharing. TM