Hi!

Recently had a strange issue and just wondered if anyone had experienced the same & resolved - I have a 2002 S-Type R, and have a slight hesitation issue when driving on the motorway (sounds similar to others I have seen people complain of on here - i.e. it runs fine at idle, is fine if you kick it down a gear etc), however no fault light on the dash - I did read the fault codes, only P1111 showing up.

Wanted to try replacing the coils as have seen some people had luck with this, and I did the same on previous car (S-Type 3.0 V6), felt very similar and replacing the coils resolved.

Jaguar wanted £51 + VAT per coil, so I had a look around for others and found some on the British Parts website, came out at £260 including VAT for all 8, so went for that - they confirmed they were the right ones for the car, and I could see the connector on there was the same (mine are 4 pin, as were the ones on the site). So I went ahead and bought these - the part number is AJ810445. They turned up and I fitted - they appeared to physically fit ok, and they had the right 4 pin connector, however when trying to start the car it would start, run for about 2 seconds, then shut down and display the "Restricted Performance" message on the dash. I double checked everything connected ok, tried again a few times but same result (also checked for fault codes - a whole bunch came up, which I reset, tried again but again same result).

So, pulled all the coils and put the originals back on, reset fault codes, and the car runs fine (bar the original issue of the slight hesitation when I'm on the motorway. Slightly annoying as British Parts wont refund the coils as I had fitted them, but there you go.. Just wondered if anyone else had had this and if anyone managed to find after-market coils that work or whether its just bite the bullet and pay 51 quid plus VAT per coil from Jaguar?

The original coils on my car were:
Denso 2W9312A366-AB / 099700-0710

The ones from British Parts were:
AJ810445

Cheers!
Mike

 

As they don't work, English law means they have to refund you.

You can remind them of your rights and then if need be issue a claim - easily done online and cheap. (You'll be surprised how easy it is, no lawyer needed, and just claim the total cost inc. VAT plus any expenses you incurred.) In case you paid by credit card you can approach the card firm but frankly the online claim is easier.

The law's view is that they must work. It is fine that you fitted them - how the heck else could you find they didn't work???

 

I would buy one genuine coil and swap out one at at time to see if fault disappears at one cylinder?
It could be somthing else like throttle body etc

And claim money back from British parts also.

 

Thanks for the replies both.. I started saying something similar on the phone with them, but the person I was speaking to got a bit shirty and I wasn't really up for an argument, maybe I'll give it another go.. Good idea swapping one out at a time will give that a go some point soon, cheers!

 

If you don't have any mis-fire codes or pending mis-fire codes I would look elsewhere.

Do you have a scanner where you can see pending codes or mis-fire rates?
We need to remember that combustion is a statistical process and even a car running fine will have some percentage of mis-fires.

Can you monitor fuel trims while driving? That might give some clues. Have you replaced the plugs?

My 2005 STR at 123K miles has all the factory coils so they seem to last.

Are you familiar with the power brake elbow that tends to leak? You could have a small vacuum leak causing your roughness. Again more data is needed.

The cars are complex and just changing things rarely works.
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Thanks for the reply - I just have a bluetooth OBDII adapter and read fault codes off using a mobile phone (running Torque) - it does let you read off pending codes, and tells you if there's a misfire fault, don't think I can see the misfire rate (unless it just throws different codes for that.. (?).

Can't monitor the trims with the kit & software I have currently. Interesting to hear you've done 123k with the original coils, are yours the same Denso ones I have?

Wondered about vacuum leak - no I was not familiar with this so thanks for the tip, will look for other posts on that.

 

Yes I think they are Denso coils but have not checked. I thought the Torque app does allow you to monitor fuel trims? Maybe not as I have not used it.

It's real hard to fix a borderline coil/ignition problem.

If you don't know if or when they were changed you might consider swapping in a new set of plugs. That won't be as expensive as changing coils.
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Might need Torque Pro for fuel trims - quite cheap but not free.

Misfire counters are probably OE diag tool only. Maybe AutoEnginuity as well? Cheaper to buy a coil.

I'm still on my original coils at 120K but have a spare just in case.

I'd take out a claim online if they won't refund https://www.moneyclaim.gov.uk/web/mcol/welcome

 

Just to update on this, it was a coil, number 7 cylinder, it went completely the other day, and gave P0307 fault code. Replaced the coil with one from Jaguar and the car is now working fine and the hesitation thing has gone.

As an aside - the ones from British Parts are very similar to the ones I got from Jaguar - the part number on the side is the same, only discernible difference seems to be the size of the aperture which fits over the spark plug; the Jaguar ones are slightly larger so seem to fit over the plugs a bit easier - the ones I got from BP were a bit tight (one of the ends of those ones actually popped off when I was removing them - and was then a right ***** ache to get out of the spark plug hole).

Anyway - thanks for all the responses!

 

Interesting.

Good to hear it's working!

 

I think that I have said this before, but I replaced all six of mine with a set off eBay for $66 including shipping. That was four years ago and doing fine.


I am not a fan of the overpriced OEM units which really didn't last that long anyway

 

Tony - you say 6 so I'm assuming you have the 3.0 V6? I had one of them previously and as you say, I managed to get a whole set for a very reasonable price (off EBay from memory). The ones in my 4.2 V8 are different though, and aftermarket options seem to be very limited (the only ones I could find were the ones I mentioned in my original post, which were cheaper but then didn't seem to work. If you know somewhere I can get a full set for the 4.2 v8 for that price I'd do it in a second though!