Newest update follows.
Ordered a set of 6 used but original coils. Will replace all six. Also ordered a set of new spark plugs champion rc12yc.

Here's my question - the gap of the new plugs is 0.75mm or about 0.03 inch. I read somewhere that the gap should be round 0.9mm. But the smaller the gap the easier is for the coil or am I wrong.

What do you think guys, should I make the gap bigger to 0.9mm or leave it 0.75mm? Whats the best for this car.

Thanks.

 

http://www.jagrepair.com/images/TSB/...6%20Engine.pdf

As the coil over years gets weaker bring the gap smaller , but the coil is on it's way out . higher current across the gap .

To make a new coil last longer bring the gap larger to the 0.9 mm , but no larger . lower current across the gap .

Destructive heat is a function of higher current

 

Spark Plug spec for the AJ16 engine is .035"...or 0.9mm

 

An interesting note is that for engines that suffered rough idle, hesitation or other drivability concerns, Jaguar issued a TSB indicating the spark plug gap should be set larger, at 0.038 inch / 0.96mm. This TSB also confirms that the revised spark plug specification, Jaguar part EBC 8143, is Champion RC12YCC:

05.1-36 Rough Idle/Drivability - Diagnosis to Follow Prior to Replacing MAF

But Parker's advice seems like a good idea if your coil is failing.

Cheers,

Don

 

I guess it is possible that over time we'll find some inexpensive aftermarket coils that are as good, or nearly as good, as the Japanese OEM coils.

Perhaps these QYL units are? I have no idea, but please keep us updated over time how these work out for you.

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When I bought these QYL coils I was pleasantly surprised at the quality of construction. They were actually a little heavier than the original Japanese coils. I had not actually tried any other generic coils but when I was looking at close up pictures on Amazon of other brands of coils I noticed that some of them had sub par molding, rough edges and such which to me at least, can be a sign of lack of quality control and if that is on the outside that the consumer can see, what is on the inside?

The fact that an electronic component in made in China does not necessarily mean that it is inferior. Most of our consumer electronics are made in China, it is all about quality control.

I remember when the original Japanese coils used to sell for $300-$400 each. $2400 for a six pack of coils! The markup on these coils was insane. An ignition coil is a fairly basic device, nothing high tech and should be priced as such.

 

Thanks, I may be buying a set for some testing. I'm suffering from what I think is a heat-soak related issue that causes intermittent stalls at idle or low RPM. I'm checking out the crank position sensor next because I already have a new one on-hand. But if that isn't it, perhaps one of my coils is dying. For $60 for a set of 6, these coils would be a cheap and quick test since it is so hard to find which coil could be failing.

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Hi Gents, I am having similar problems. Crank sensor is only a few years old, coils replaced about ten years ago, could they be worn out? It has been a weekend car for the last seven years, so not that many hours on then. I would suggest, as I think previously mentioned, cleaning the under hood earth points and using contact cleaner, not wd40 or similar, to clean the connections on the ecu and any relevant connections. This previously solved some running issues for me.,

 

If your symptoms are the same as the first post there are some free things you can try before component change .

The main engine block ground from the lower starter bolt to the frame . Best to get from under the car with a 13 mm on the starter bolt and a 10 mm on the car frame .

Injector cleaner in the tank ( X brand recommended by many ) . The injector pulse width is at it's shortest and most critical at idle . Storage time may have gummed up the injecors

Old fuel ?

Do you have the start but stalling after a couple of seconds as the fuel rail is drained of it's initial prime charge or pressure amount . A not completely failed CKPS related issue .

 

What's the code for the QYL coils please..is it still a LHE1510AB ? ..I'll see if I can find them in the UK?..and what brand were the cheap ones that failed?

 

trampintransit, I bought my QYL coils from Amazon over a year ago and mine are still working great.