Any Ideas?
My 2001 XJ8 114k, is misfiring. I had tensioners replaced in March 2011 at 102k, along with plugs and hoses and all 100k but O2 sensors. My mechanic said he had an issue with a plug seal or gasket (don't recall exactly) not holding but resolved before I picked up the car. However, at that time I noticed a slight low pitched growl during acceleration that wasn't occurring before and a slight increased fuel usage.
Just in case, I have included a recent history:
About 2 months ago I was having the oil changed and the tech pointed out a small oil drip from the rear driver’s side of the engine. This explained the burnt oil smell I had noticed after exiting the car. However, I have never had any oil on the garage floor. I called my mechanic and he asked me to bring it in when I had a chance. About 2 weeks ago I noticed an occasional sluggishness or missing at idle and low speeds. It didn't happen with every start but consistently increased over time. On the 6 mile drive to the shop the restricted performance light popped. The car only ran smoothly during acceleration and spit/sputtered/shuddered during steady speeds and idle. I always use Shell premium fuel purchased from a busy interstate travel center, in addition to regular oil and filter changes with Mobil 1.
Thanks!

 

Welcome to the forum!

Do you have a CEL? Have you had codes read at you local auto parts store? There is not enough information to make even a WAG.

 

Thanks. I will get them from the mechanic in the AM.

 

you can have alot of coil misfires and never set a CEL. You need a scanner that shows misfire counts like Jaguars Genrad(no longer made) you can have thousands of misifre counts but without a CEL or seeing counts, youre guessing. you could always replace all the coils

 

Thank you for the advice and I apologize for the delayed post. I did have CEL but not until after the third day of initial rough idle even though it wasn’t being driven. My mechanic and I played phone tag for a few days. Unfortunately, when we talked I was driving and was not prepared to write the quantity of codes he was telling me. It was 7 or 8 and all related to the misfire. He now has that corrected. However, now the problem is with the injectors on the driver’s side which are not working. They have been cleaned and are working perfectly on the passenger side.
I will be meeting with him Monday and will get a list of the codes. He seemed perplexed by new injector issue. Any ideas or suggestions on this latest issue will be much appreciated.

 

Why the injectors would be fouled on one side and OK on the other is befuddling.

Get us the codes. He has that all corrected and knows that the problem is the injectors on one bank? Missing information . . .

 

After doing the VC gaskets and secondary tensioners on my car, I have had a coil go out and a roughness/sluggishness when it is first started after sitting more than a few minutes. I am going to replace the plugs with 5464 NGK I think, or maybe it was denso and gap them at 0.035" to see what that does.

 

I would suggest doing a compression test before going too much further with it. The plugs are super easy to get out and it's always good to have the peace of mind knowing you have a mechanically sound engine before going after fuel/ignition. I have seen VVT units slip on the cams when not torqued correctly after tensioner/chain replacements also. Not that coils or a bad MAF couldn't be the culprit as well. Injector failure is definitely less common, however.

 

I was able to go to the shop today and have an update. All codes were related to misfires on cylinders 5, 6, 7 & 8. He is currently not getting any new codes. Fuel pressure, compression, MAF, coils & a list about a page long all are good. He did find a small air leak and it has repaired it. Fuel rail has power and pulses some at higher 2k+ rpms.
Is it likely it could be the ECM or an electrical issue?

 

hes wasting his time, if you look at the wiring diagrams(i just did and never do that cause its my time on here and money)
he would find that the injectors are all on a single splice to the injector relay and individually ground pulsed to fire. the coils and split and batch fired 4 at a time 2 on each side of the engine. so you wouldnt have a bank down for those either because they too are on a single splice and use the same connector on the engine so the likely hood that a connector is unplugged would be nill. You would have misfires on 2 cylinder of each engine bank, not down 1 side> even true with the ECU IF it were faulty
I still say pull the damn cam covers and check timing. the drivers side IS the side that will be timed incorrectly most of the time and cam out of time WILL give misifres on that bank. He's wasting time and your money to not check this. It takes 10 minutes

 

In 100% agreement with Brutal. Remove the crank sensor and rotate the engine until you can see an opening stamped into the flywheel unlike the rest (half moon on top) for the TDC tool to lock into, with the cam covers removed check and ensure all four "flats" on the cams are aligned with eachother. This job requires special tools to do if you were to re-chain or re-guide the motor, they are not required to check the timing though, the cam flat(s) should be visibly off if it's out. I've seen many techicians cost people lots of money throwing ignition/fuel components at a driveability problem on a car that needs internal mechanical engine repair. At the VERY least have him run a vacuum test on it and post us the results.

 

Thank you! I will get this info to him before work in the morning. Maybe I will get my baby back before the 2 week date on Monday.

 

Well there is no problem with the timing. Could there be an issue with the ECM & it not be giving off codes?

Also, let me add some recent background info that might help. A few weeks before the misfires I noticed about a 10-12% decrease in fuel economy and a couple months before that the light for the abs/traction began turn on for a day then off for a week or two. I was preparing to check the connections for soldiering issues when the misfires began.

 

Check the compression. Still sounds like cam timing.

 

Another random guess - a catalytic converter. A slight blockage in one of them can as does cause random missfires. It can also explain the extra fuel being used.

The burning oil smell - a drop of oil onto the exhaust manifold from leaking cam cover gaskets - have you had them replaced? If not do so.

 

Still sounds like timing to me too. How was timing ruled out as a possible cause? Did your tech pull the cam covers, rotate the engine to TDC and check the flats on all four cams? The catalysts on these cars are fairly robust, it has to have major misfires and be dumping lots of raw fuel in them to cause failure. I've seen nikasil engines wash out several times and the cats still survive afterward. If it were an X400, X202 or X350 I could see a potential catalyst fault, they are quite a bit more fragile. The ECMs are practically bulletproof. I think I've seen one fail in 10 years of X308 experience. You might have to break down and take it to a Jaguar dealer. Big $$$ but it will be diagnosed and repaired correctly.

 

Your ABS/Trac fail is totally unrelated, if its a C1095 it's the cold solder joint issue in the ABS module. If is comes on during cranking and extinguishes after start up it's voltage drop from a weak battery. Somewhat more rarely it is a fly lead for a wheel speed sensor or wheel speed sensor internal failure.

 

Misfire issue on 2001 XJ8. The codes are:
PO300
PO305
PO316
PO332
PO357
PO1000
Any and all advice is much appreciated.

 

a dodgy crank sensor?

 

Would it start and run (albiet poorly) if the crank sensor is failing?