Hi,
I broke down on Thursday night, (M11!!) the RAC guy diagnosed the problem as the ignition coils, possibly thre or four were knackered. The car started to play up on the motorway, no power, mis firing and eventually stalled, I managed to get it to the service station, it starts, just, and then sounds and feels like a bag of ball bearings and then stalls, if you rev it high it hives the same reaklly bad uneven running, sounds eally bad. As I mentioned at the beginning, The RAC guy said it was the coils, question is, is it the coils and secondly before I spend a fortune, how do you test the coils?
Many thanks

Nic

 

There is a device, I've seen advertised, designed to test ign. coils on the car. It is supposedly available in auto parts/speciality stores. I saw it demonstraded on a tv show with glowing comments. It was not expensive.

I have never seen or used it but I always thought if I had a problem like yours that would be an approach to a fix.

KBO mate.

 

Hi,
I was hoping that I could test with a multi-meter? take them out and test individually??

Regards

Nic

 

Multimeter test is good but not comprehensive. It won't show internal shorting under laod/high voltage. You could at least compare the good ones with the suspects.

The question in my mind is "why mulltiple simaltanious coil failures"?

 

Get one good spark plug. One at a time, put the spark plug into the coil and use a jumper lead to connect the metal body of the plug to the electrode of the plug in the engine. A good coil would be able to fire both plugs.

 

Hi Guy's I am an architect not an engineer!! Please be ind to me, I have taken the first plug out now that I have the coil out, the plug is sooty and the gap is about 2.5mm which I know should be 1.1mm. Should I replace all the plugs before I start changing coils?

Thanks

Nic

 

It helps to know what year, model and engine that you have.

It is always best to start with a tune-up, so the new plugs won't hurt. Get a tube of Never-Seize and put a little onto the threads of the spark plugs before installing the plugs. Before removing the plugs, look and see if there are carbon tracks on the sides of the plugs. You may need new rubbers to keep the sides of the plugs clean.

Check the air cleaner too.

I agree that there may be something else going on under the bonnet, but simple stuff first.

 

COPs are a known problem area. I, personally, switched to Accel brand coils listed as for a Mustang 4.6 engine. Replace the plugs at the same time. No trouble in almost 4 years.

KS

 

Nic,

The diagnosis you got from thr RAC person? Was it a casual observation or the result of some checks?
Something tells me we could be "barking up the wrong tree" here. You need to pull the codes before you tear into the engine.

As Red Skelton used to say "It just don't look right to me boy"

 

To the OP, I would move this post to the appropriate section for your car but I haven't a clue as to which model you have.

If you are looking for specific diagnostic information you need to provide Year, Model.

 

V8? tensioners?

 

Get the fault codes read or buy an OBDII reader and read them yourself...otherwise this is purely a guessing game.

 

Multiple coil failures simultaneously??? I don't think so...

 

You would have fault codes galore, sounds more like an air leak to me, this will make you engine sound like a bag of nails when running, really need to know if it is a supercharged engine or not

 

Thanks to everybody that posted replies etc, the RAC (Breakdown guy) diagnosed that it was possibly 3 or 4 coils gone as it sounded so bad, no codes when he connected his device.
I removed and replaced all 8 spark plugs yesterday, a bit of a pain as it also runs on LPG, started first time and sounds and runs great again. All of the plugs were black and sooted up, a couple were corroded and one the ceramic was cracked and broken. Fingers crossed it is now ok.
Once again thanks for replies.
Car is a Jaguar XKR 1998 4.0ltr supercharged.

Regards

Nic

 

Does LPG vs petrol change anything in the combustion process?

I'm glad it wasn't the tensioners, which did make sense after plumsauces post. Have you had yours changed Nic?