Egad! In an earlier post, I noted that I was getting the Restricted Performance message on my recently purchased Jag. With a pile of maintenance receipts dating back to original purchase date, I was so confident I'd be problem free for some time at least. First DTC code checks showed P0300, P0352, and P0304 as I recall. I switched ignition coils between cylinders 2 and 4, to test for new codes, then received new messages with P0302 as well. Noticed cylinder 4 had a newer (but not OM) ignition coil and since I had access to an original, unused coil I found on eBay, I installed it but with no positive results. Had to leave the problem alone for several months to deal with location change but I'm investigating again. Yellow check engine light appears immediately upon start and restricted performance message quickly shows as well. Latest DTC code checks include: P0300, P0302, P0304, P1316, P0352 and P1638. The engine is extremely clean and the ignition wiring looks to be in proper condition with no cracks, etc. I haven't looked at plugs yet. Car has 85,00 miles. Where the heck do I begin? Any advice from a guru would be greatly appreciated.

 

I would first mask the coils with painters tape and mark cylinder identification on them so you don’t lose track of the original location. Swap the two front coils with the two rear coils and clear the codes prior to starting the engine. While the coils are out, look down inside the spark plug wells with a bright flashlight and see if there’s a lot of oil on the plugs themselves. A little is ok but, if it’s pooling up to the porcelain or higher, then that’s highly recommended to get cleaned out next before trying to diagnose the misfiring.

 

The 1316 code reveals several possibilities, but my first guess would be the coils.

• Cylinder compression low
• Low fuel pressure
• Clogged fuel injectors
• Faulty / worn out spark plugs
• Faulty ignition coil
• Faulty fuel injectors
• Faulty Engine Control Module (ECM)

 

Thanks for your replies. I will try the coil swaps and report back. Much obliged.

 

As suggested to me, I carefully masked (for ID) the ignition coils on the 2,4,6,8 cylinders and switched coils 2 and 4 with 6 and 8, respectively. Subsequent DTCs were as follows: P0300,P0302,P0304, P1316,P0352.So, evidently, it is not the ignition coils. Spark plug wells are absolutely dry and spotless. As RandyS mentioned (regarding the P1316 code), I guess it's a matter of checking off each of the several possibilities one by one.
Where should I be looking first?

 

1. P0352
2. The code triggers when there’s a problem with the coil number 2 driver circuit (which corresponds to cylinder #2).
   • The PCM (powertrain control module) monitors the performance of ignition coils.
3. Possible Causes:
   • Bad ignition coil on cylinder #2.
   • Bad spark plug.
   • Corroded or damaged wires related to the second cylinder coil pack.
   • Faulty coil driver circuit.
   • Issues within the ignition system.
   • Damaged wiring harness between the PCM and coil pack.
   • Vacuum leaks.
   • Blocked throttle body due to carbon accumulation.
   • Electrical issues within the ignition coil circuit (e.g., faulty camshaft position sensor, crankshaft position sensor, etc.)
   • So...there you have the extent of could be causing it.

 

This cylinder identification is for all X308’s.

 

Thanks to RandyS. Looks like I've got my work cut out for me.

 

I'm confused by this diagram. This indicates it is up to 2002.5 model year and shows two banks which are numbered the same (1,2,3,4). I have a 2003 model year (4.0 L) and all diagrams I've seen show cylinders marked as being numbers 2,4,6,8 on the driver's side starting from the engine front (on a US car), with 1,3,5,7 on the other bank. A diagram I reference, shows a heading for "Cylinder Numbering Diagnostic Reference- V8" (used by engine management software for DTCs and datalogger) and it shows this as being for the current AJ-V8 to ISO standard. Just below that is another listing: "Alternate V8 Cylinder Numbering" (for some S-types and XK AJ-V8 before 2003 MY as well as V8 XJ before 2004 MY. Well...mine is a 2003. Do you see my confusion?









On same chart, just below Am I reading this in(usedcorrectly?

 

Although you have a US 2003 model for licensing, it is really a 2002.5 (last of the 308 series) -- in the UK, the 350 series with the 4.2 engine was marketed in 2003. Your 4.0L motor is 1 - 4 right side (looking forward), 5 - 8 left side.

 

The first thing to check is the electrical system to make sure you have enough voltage to run all the electronics. You should have 12.6 with the key on and 13.5 to 14.5 with the engine running. Do the checks according to the attachment; it's about a 10-minute job. There's some good information in there, but all you're checking is for proper voltage. These cars will throw random codes if the voltages aren't correct.

If the voltages are good, then continue on with the advice from above.

 

Thank you so much! I have been keeping my car on a CTEK charger so I'm pretty sure the voltages are good. I will double-check and proceed as advised. Thanks a million.

 

Jim, thank you so much. I kinda feel like an idiot. I'll just walk around to the other side of the car then and do my inspection way over there. Much obliged and thanks for setting me straight, sir.

 

Keeping a charger on is good, but what you're looking for is the higher voltage with the engine on. I learned this the hard way three years ago when my brother flew out from Austin and I drove him home on a leisurely trip from Northern Nevada via San Francisco, Long Beach, San Diego, then the interstates to Austin. Of course we did the scenic route from SFO to SAN. On the third day of the trip I started getting DTCs, most notably all the P03XX codes. All 8 cylinders showing misfire. The car was running good, so I cleared the codes and pressed on. This happened about half the time I was driving. Got home and took the car over to a neighbor that's an electrical engineer. I hooked up my Autel scanner that shows the voltage in the upper right corner. I started the car to take him for a ride and before I put it in gear, he said my alternator was out. He noticed that the voltage didn't move off of 12.6 when I started the engine. Replaced the alternator and all codes went away.

 

Thank you, sir. Funny thing...yesterday, after swapping coils from two cylinders, to see if the coil packs were indeed faulty (as indicated by my OBD scanner), my car very briefly showed a "restricted performance" message (as before) then began running smoothly with no MILs. I let it run for 15 glorious minutes with no stumbling whatsoever and thought I was headed for brighter days. The CEL was still on, but I figured my beloved beauty may just need a little drive-time to clear up those nasty old computer messages. Nope. Started her again today, and right away...the gremlins were back. Now, MILs show ABS light on, as well as "ASC" and "TRAC CONTROL" off. All the earlier codes showed up on the scanner, of course. Awwww, Crap! I checked the battery and it shows over 13 volts, so that's all good. But...I haven't checked the battery while cranking the engine. Must I have an Autel scanner to check this situation? Maybe it is indeed alternator related?








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With a fully charged battery and no charging system issues, about 14.2v is what you should be seeing with no load’s whatsoever. 14.1 - 14.3 is about average that I’ve come across on these cars. If you’re in the 13’s, I’d look for a dirty/loose power or ground connection that could be warm to hot so be careful. I suppose it could also be the alternator if it’s one from an auto parts store.

 

[QUOTE=Hotdogger52;2753694]Thank you, sir. Funny thing...yesterday, after swapping coils from two cylinders, to see if the coil packs were indeed faulty (as indicated by my OBD scanner), my car very briefly showed a "restricted performance" message (as before) then began running smoothly with no MILs. I let it run for 15 glorious minutes with no stumbling whatsoever and thought I was headed for brighter days. The CEL was still on, but I figured my beloved beauty may just need a little drive-time to clear up those nasty old computer messages. Nope. Started her again today, and right away...the gremlins were back. Now, MILs show ABS light on, as well as "ASC" and "TRAC CONTROL" off. All the earlier codes showed up on the scanner, of course. Awwww, Crap! I checked the battery and it shows over 13 volts, so that's all good. But...I haven't checked the battery while cranking the engine. Must I have an Autel scanner to check this situation? Maybe it is indeed alternator related?

No, you don't necessarily need an Autel scanner; I'm sure there are other brands that perform the same functions. I bought the Autel 'cause it was on sale at JB Tools that day.