Hi all, my name is Paul Bennett and I have just joined the forum. I used to be a member of roadfly but cannot seem to access their website anymore. I have a 2000 reg. XJR which has gone into limp mode about a week ago. Ihave changed the plugs which has made no difference and now I strongly suspect an ignition coil. The scanner has detected a random/multiple misfire and one or two other things but is not specific to any cylinder. I think my course of action now will be to buy a new 4 pin ignition coil and systematically work through all the cylinders starting the engine after each coil replacement until I find the culprit. The error code is PO300. Any and all suggestions are very welcome!

 

I believe these engines are normally " pretty good" at identifying which coil is misfiring, although my experience is with the aj26 variant, and as you know, the AJ 27 has a different coil circuit. I would reset the ecu and then see what codes came up and report all of them, OR just do as you said and try the partsvexchange method!
BTW road fly is essentially dead, at least for Jaguars. Your best technical info is right here. RF was more centered around which polish to use on your chrome inserts, anyway.

 

Hi Sparkenzap, It's good to hear from you after all this time. I posted a couple of times on Roadfly about two and a half years ago when I bought the Jag and this is the first problem I have had with it. Yellow light on dash accompanied by restricted performance. First happened a few weeks ago and then cleared itself for a while then came back. I bought a cheap scanner [never used one before] and it has come up with a host of things- P0123 throttle position sensor switch 'a' circuit high-P0456 evaporative emission system very small leak detected-P0011 a camshaft position timing over advanced-P0022-camshaft position timing over retarded bank 2-P0300-random/multiple misfire detected-P0055 HO2S heater resistance bank 1 sensor 3- and a load of other pending fault codes. Sounds like a wreck doesn't it but the car is in lovely condition and has only done about 73000 miles! I don't know how accurate these Autel scanners are but you can frighten yourself to death with them. Seriously though I think the only real problem is the misfire and from what I can gather it points to a coil as apparantly they are a weak link in the ignition system. Anyway I have just ordered one on e-bay should be with me Thursday. I intend to change them all until I find the faulty one. I will start with bank 2 as that's the side without the airbox and I might get lucky and find it early. Wish me luck and please stay in touch, with engines as complicated as this we need all the help we can get!

 

Hi,Paul here with an update. The ignition coil arrived yesterday but I couldn't do the job because of work commitments. I started it today as I have a day off and wanted to get it done even though it was raining quite heavily [not unusual in Manchester]. Started on bank 2 first cylinder from front and worked back towards the bulkhead starting engine with each coil change. It's not prudent to work on ignition systems in the rain without cover- could end up with more misfires than I started with. Was just beginning to lose hope when I nailed it on the last one. Job done and the Jag purrs again. Love it.