Not sure where to put this topic..Hello:

Last year I purchased a 1997 XJ6 4.0 VDP.
She has 65,000 miles on her.
Last week I started the motorcar up and immediately noticed a sudden vibration, a very rough idle, (it has since stopped idling rough and the check engine light came on) The rough idle eventually lead me to searching this forum. I have not driven the the car since I noticed the rough idle i have just started it 2-3 times in the garage for about 2-3 minutes each time.
I have been in touch with Welsh and SNG Barratt and talked about replacing the coils and surprisingly enough got two different responses on prices and quality.
But the main point for this post is that since the engine idled rough – the check engine light came on. If I swap out the coils, will/should the check engine light go of by itself?
Thank You,
Wayne.

 

Read the codes & are they consistent with faulty coil(s)?

You're in the wrong forum BTW.

The MIL will go off after 3 warm ups, if the fault is fixed, or if you clear the codes.

 

Wayne,

I've moved your question from General Tech Help to X300 forum. This is the place to post technical questions about your model.

The first step in troubleshooting why the MIL is on is to have the codes read. Without that it's guesswork as to the cause and throwing parts at the vehicle can get very expensive.

Graham

 

Sir:
Can I ask you what you mean by MIL?
Cheers.

 

Malfunction Indicator Light, generally used interchangeably with CEL---Check Engine Light

I agree on reading the codes and going from there

You want the coils made by Diamond Manufacturing in Japan. They are the true OEM supplier. SNG Barratt knows about them

Cheers
DD

 

Thank You.

 

A coil in the process of failing my not throw a fault code, so a lack of codes does not mean they're good.

 

And... considering the results forum members have reported for replacement coils, I would only change individual coils suspected bad. READ THE CODES!

 

It sounds like I need to purchase the computer to read the codes, I have no idea how to do this since, sine I have never had to do anything like this before..
Is there a particular computer that I need to buy? I believe it hooks up under the steering wheel?
DUMD QUESTION - Can I do damage hooking up the comp that reads the codes? Is there anything in particular that I should be aware of?
Cheers,
Wayne.

 

Wayne-

You're not looking for a 'computer' per se to read the codes, it's simply a tool that hooks your car to a computer. A 'fancy wire' would be a better description.

The most common type of code reading tool is the ELM327. You may wish instead to take your car to a carts parts store. Most times they will read the codes for you.

Also- do not start and run the car for short periods. That does the engine no good and can in itself cause problems.

 

Wayne, as Mikey said, most any auto parts store will read the codes for you for free. I would counsel you to get a printout from them or at least take a pad and paper and copy down the exact codes they get, rather than their explanation of what they mean - which they will be all too happy to give you. Get the actual codes, of the format P0411, P0303, etc and post back here. They will likely tell you it is this or that sensor bad, or cyl#x misfire or whatever, fine, thank them, but get the actual code from them, as they may or may not be correct on the actual cause. Better info available here in the stickies, but I imagine if you just post the codes in this thread, there will be several members who'll recognize them right away and point you in the proper direction.

 

Thanks, I have a better understanding now. A mate of mine has told me he has one i can burrow, taking the car to an car store makes a lot of sense as well to collect the codes.
You are 100% right - having the tool to read the codes should be apart of my tool kit now.

My other ride is a 1982 CJ8 with an inline 6 - so I have never needed to check codes..

You mentioned - do not crank the motor for a short time. I understand turning the motor over for a short period in not ideal, I did it to see if the vibration went away (which it did)
Or are you saying do not turn the motor over incase a coil is bad ??

Thank you again for everyones help, it appreciated.
Wayne

 

I was stressing that starting and running an engine (any engine in any condtion) for short periods is not a good idea.

 

Hello:
I took the Jag to an auto shop and the chap hook up the comp and did a reading.
Below is what the print out said.

ERROR CODES READ

P0300 Random Misfire detected
P0301 Misfire – Cylinder 1
P1314
P1313
P0300 Random Misfire detected
P1316

Its all foreign to me, hopefully it’s a case of just changing plugs or coils.
With 62,527 miles, should the plugs need changing? Or are they tired and need changing?

Thank you.

 

OK- I say swap the coil from the front (Cyl #1) cylinder to the second one back (Cyl #2). Drive the car and see if the P0301 changes to P0302. If so, you have a bad coil! If not, you may have a bad #1 plug or bad injector, or bad compression on #1.

Or, change the number 1 coil and see what happens.

But, in either case DO NOT LET ANYONE TALK YOU INTO CHANGING ALL OF THE COILS. They are not all bad, one failing does not portend failure on the others, and replacement coils are suspect, at best.

BTW, you ask about 62,000 miles. Yeah, low mileage for plugs, but you got durned near 20 years on 'em!

 

I'm with Spark, unless you know the plugs were changed in the last year or two, you may have 20 year old plugs.

Plus the OEM plugs are "plain" plugs, not some esoteric platinum or iridium set that is supposed to last 100k miles. The "plain" Champion plugs specified for the X300 probably will last several 10s of thousands of miles if pushed, but since I put on 15-25k miles a year I go ahead and change my plugs annually since they are about $2 each and so easy to get to.

Be sure to get the correct Champion plug, and don't be tempted by some "high end" iridium, platinum, "split/cross/nuclear-core-of-galaxy fire" plug. The X300 is very sensitive to the correct plug. Fortunately you can find the RC12YC at any Walmart garden shop for uber-cheap. Yep, they are lawn mower plugs


AJ16 (4.0L)
EBC 8143 = Champion RC12YCC(if one can find them) or RC12YC
0.9 mm (0.035 in)
22-28 Nm (17-20 lb ft)

https://www.jaguarforums.com/forum/x...4/#post1450183

.

 

Great advice with the plugs chaps.

Since they are 20 years old I am going to change them all out.
I do not know what plugs are in there now, but when I purchased the car I bought it from a private seller in RI. He drove the car to a well known chap called Dana in MA (The folks at Welsh know him well so I felt confident in him) and he did an inspection on the car for me.
He made a short list of certain items to use, - steering fluid, oil, brake fluid etc and he did say use NGK plugs and change them about every 30K - I do not know what size the gap needs to be on the bottom of the plug though.
(The plug issue does concern me because I have read use Champoins - or is this more of a preference)?

I will order three coils and start with cycling number #1
(DUMB QUESTION) Cylinder one would be by the front grill, not aft by the fire wall?

Bad Compression, bad injectors concern me because I have no idea how to fix an issue like that and I see $$$$ at the local Jag shop..

As always,
Cheers,
Wayne.

 

Since the car is new to you, how can you be sure the plugs are 20 years old and not recent replacements?

 

Good point, who knows

If it were worth the effort, I wonder if a plug is stamped with some batch/series number that indicates when it was manufactured?

But to be honest, to me it isn't worth the effort on the AJ16 since it is so easy and inexpensive to replace them. So if it is a "new to me" car and unknown, I'd just spend the $15-20USD and replace them for peace of mind as part of my "new car" tune-up


.

 

Well, spark plug debates are often akin to "oil threads" although I'd like to believe that in many cases the spark plug discussion is a little more objective as one can often observe immediate results or impacts from plug choice.

So I'll let you search this forum for the myriad threads discussing plug choice, and to be fair there are many that will say that the NGK plugs are fine.

In my reply above, I linked to a post that contains two of the significant spark plug threads, and includes a link to the Jaguar factory TSB on spark plug specification as well as the general forum opinion on the correct type and gap.


But I will go out on a limb and say the general X300 forum wisdom is that the NA and SC AJ16 appears to run best on the Champion RC12YCC(if one can find them) or RC12YC. They do need to be changed a bit more frequently than iridium/platinum plugs, but the benefit is smoother running.


Yes, the cylinders are numbered 1-6, starting with number 1 closest to the radiator/front.


You can check compression yourself, or a shop can do so. It is a very easy procedure where the spark plugs are removed and an adapter with a pressure gauge is screwed into the plug hole. Then the engine is turned over (not run) and compression is recorded. The recorded pressure per cylinder is then compared against the service manual specifications to see if there is a problem. Problems can vary, but most commonly are gasket or ring issues. Fortunately these seem to be rare with the inline 6 AJ16. Compression issues seem to be more common with the newer V8 engines.

Injectors... hard to really test them on-car, unless you know they really aren't working. But fortunately they are pretty easy to remove, although you do have to be careful with the wiring connectors and other 20 year old plastic bits as they break easily. Once removed, you have several choices such as "http://www.mrinjector.us/" and another fellow who specialized in rebuilding Jaguar spec injectors (forget his name, but Google will turn him up)... both of which come highly regarded, who will rebuild your injectors for about $15-20 each. Then you have "good as new" injectors. So in this case, if you are doing a general "20 year tune-up" ... like the spark plugs, you might consider just having the injectors cleaned for peace of mind if you have the time & money. I've had it on my list for some time, but just haven't gotten around to it as AFAIK they are flowing fine. Plus if I have the injectors cleaned for about $120, I'd probably go ahead and refresh the fuel pressure regulator too, which is another $100. That total cost keeps me from "fixing something that (probably) ain't broke" right away



.