I have replaced coil #3 twice recently (and it is such a pain on this car) now in limp mode and error code misfire on #1 and #6. [edit: Now 1, 3, and 6]

Why would two coils go at the same time? Maybe 1 and 6 is a clue to a broken wire or the such?

 

Have a seat while I climb up on my soapbox:

If the computer has set a misfire code, please be aware "misfire" wasn't the best terminology that could have been used. Misfire sounds like an ignition problem, at least to me, meaning the fuel and compression were there, but for whatever reason, the required spark was missing or weak. This might lead a good-looking aspiring mechanic to troubleshoot the daylights out of a perfectly good ignition system. I do not care to discuss how I know this.

In OBD-speak, misfire simply means one or more cylinders is putting out low power compared to the others. Pretty much anything affecting the output of a cylinder can set a misfire code. It can be low compression. It can be a valve not opening fully. It could be a clogged fuel injector. And yes, it could be an ignition problem, too, but don't overlook the other possibilities, too. [/soapbox mode off]

Two big questions: What brand of coil did you install? And did the second one come from the same source? If you insist the new coils must be good, I shall purchase you a nice white sofa. I will then settle in on said pristine sofa, eat Cheet-Os and drink orange soda. As soon as you aver the coils must be good, I shall laugh heartily out my nose, leaving an orange silhouette of myself. I'd be doing all this just to get your attention that new parts can be bad from stock.

Remember, a misfire code can mean more than just a bad coil, too. Did you change the spark plugs yet? While you're in there, I'd swap in a known-good coil from the other side.

I also wonder if you've got a vacuum leak affecting that bank. Any other fault codes?

Other possibilities are a bad injector or low compression. But I'd certainly try new plugs and a known-good coil first.

 

Did change plus but coils were generic from King Auto Parts. I did NOT replace the manifold and coil gaskets and I know one manifold head bolt does not bite. Had problems with air leaks after last session. Have an O2 sense code that has been there for a while.

 

Your last post speaks volumes Mike. Our S Types do not play well with generic coils, been that eay for a very long time.

When you remove the plenum again. Use the manifold bolt that does not tighten to pull brass sleeve from manifold. Clean and epoxy brass into manifold being careful not to get epoxy into the threads.

 

OK I ordered OEM Jaguar coils - $430

 

Ouch! Did those come in a gold-plated box with diamond accents?

In my overly inflated opinion, some OEM parts are way overpriced. It's not like Jaguar manufactures these coils themselves with some proprietary process that no one else can touch. Typically, a vehicle manufacturer has them made under contract by one of the reputable suppliers. Not sure of the details with coils, but it was probably Nippondenso, Bosch, Lucas, or one of the big names like that.

Whenever possible, I like to purchase parts from such sources. In some cases, you get literally the same part except for the name on the box. And if not the OEM supplier, nearly all reputable brands will be of comparable quality, but at a price far less than OEM. For example, I've got one Bosch and two Beck-Arnley coils on my car. I've never had to mess with the other three, but think they are OEM.

So the warning about generic coils? Yeah, those are often crap. No name EBay stuff and budget store brands? I'd certainly avoid those like a vegan at a barbeque. But I'm afraid you've misinterpreted our remarks and went too far the other way on the cost/quality scale.

Don't forget you've got some potential intake manifold leaks to consider. Those are likely to be part of the misfire equation, too.

 

SO TELL ME A BRAND THAT MAKES GOOD ONES FOR THE S-Type. I had Delphi before. i'll cancel this order if I can

 

Is this for the '07 V6 in your signature?

I like to use RockAuto for research. Here's what they have listed for an '07 V6:


https://www.rockauto.com/en/catalog/...tion+coil,7060


Note how the list is separated into economy and standard replacements. Stay away from the economy offerings. Under standard, I see Delphi, NGK, Beck-Arnley, etc. I think any of those brands should give excellent service.

Those listings also have a lot of OEM numbers and cross-reference data. Poke around online and you may be able to find other brands, if you have a specific preference.

You had mentioned previously having Delphi coils. Are they the ones that acted up for you? Keep in mind the coils may not have been the problem. There's still the potential vacuum leak, especially likely as the problem was confined to one bank. Please see my previous message where I got up on my MisfireSoapbox™, trying to make the point that misfire fault codes can be caused by many things, not just the ignition system.

Can't remember what has been done so far. Have you replaced the spark plugs yet? Those are normal wear and tear items, and well worth a gamble, even if they are supposed to be good for several bazillion miles. Since access is so poor on the bank setting the codes, I'd also recommend swapping the known-good coils from the other bank. This helps rule out the possibility of installing parts bad from stock. If the fault swaps to the other previously good bank, then it was the coils. If the fault doesn't change, you've probably got a vacuum leak over there.

 

Yes did plugs and have now got gaskets. I'll get the NKG or Delphi. The ones in now are not Delphi but the generic ones from King Auto. That was my mistake.

Thanks.

 

Phew, you had us worried. The thread started out innocently enough, with some basic replies of how you might want to proceed, then all was quiet. Next thing we know, BAM! FullPanicMode™, as we learn you've apparently sold one of your kidneys on the black market to afford some OEM parts that may not even be needed.

Fingers crossed for a good fix. Keep us posted. Only one thread is required...

 

I think I have agreement to return/cancel OEM coils

 

Good, good.

What about your kidney? Were you able to get that back?

 

Too late to go back on the kidney but I now have a down payment on the heart I need. As long as I have my liver to keep drinking all is well.

 

UPDATE
So I got the NTK coils from Rock Auto but when I drove the S-Type up to the workshop it drove JUST FINE. Only after a little while did it revert to limp mode.
Does that imply the coils are OK and its a logic/computer/loose wire type issue?

Would appreciate some input before I start working on it again.

ALSO I did the propane leak detection thing with no results. Is this a reliable test?

 

That's not enough info to say if the parts are good.

The leak detection works if you have a leak (did you check the fuel trims properly?) and happen across the leak, but if you miss the leak then no.

 

OK, so I should for starters install the coils I bought?
"Fuel Trims" not understood?

Thanks

Mike

 

Worst case the forum and indeed internet have Search features.

 

Mike,

I'm at a terrible disadvantage here because I just put up new tin foil on the windows of my house. Works great to stop the government's mind control rays, but an unfortunate side effect is that it's getting more difficult to read your mind.

Have you changed any parts since your last check-in? Not sure, picking up a faint aura "no". What about the new codes behind the latest restricted performance? I'm not picking up a thing...

Remember, for some of the less severe codes, the fault has to be present on consecutive drive cycles before they are annunciated. That might explain why you didn't see anything on the one trip, but then they suddenly appeared.

Fuel trims? Read this primer, lots of good stuff:

Fuel Trims as a Diagnostic Tool


Propane test? Thinking carburetors, aren't you? The propane test worked great with a carb, as the idle speed would quickly respond when the propane found a vacuum leak. Fuel injected? The computer adjusts fuel flow to maintain a steady idle speed. Feed propane into a vacuum leak, and you might never notice it if only monitoring the idle speed. You have to have your scanner reading live data, and watch for the short term fuel trim to respond to the extra fuel. Same thing, only different. That fuel trim primer describes how intentionally adding a vacuum leak causes the short term fuel trims to go one way. If you can monitor the same trim while adding propane through the leak, you'll see the trim go the other way.

One more caveat with any kind of vacuum leak test: Not all lines are connected to manifold vacuum at all times. There are various valves that shut off certain lines under different conditions. Consider the vacuum line that actuates the EGR valve, for example. At idle, the EGR valve is commanded closed. The valve is spring-loaded closed, so the muscle line is not under vacuum at that time. This line could have a gaping hole in it, but since no vacuum is present, the propane will not be drawn in at idle. For a successful propane test, you have to have a very good understanding of what each line does and when it is under vacuum. Sometimes you have to bypass various valves for a truely comprehensive check out.

Same thing with a smoke test, what with check valves and other control devices. Depending where the leak may be, smoke may not reach it.

What about the variable intake runners? Parts of the intake plenum are closed off under certain conditions, but I'm not very well versed on the subject. All I know is that it's possible some areas may not be active at idle, and thus a propane test won't find any leaks there.

So please get back to us with the current codes and fuel trims. I haven't done much interpreting of fuel trim data, but other guys are more sharp with that subject. And yeah, I'd get those suspect coils swapped out, but keep track of what was happening before starting. Resist the temptation to change everything under the sun in case something else is bad from stock, didn't fit properly during installation, etc. I like to make small changes one at a time whenever possible and retest as I go. That way if the situation gets worse, you'll know right away it was caused by the last step. I realize this isn't entirely practical with the big intake plenum blocking access, but I'd stick to replacing the suspect coils/plugs and any relevant gaskets for starters, and then retesting.

 

Mike,

It really would help present the full picture if you could post all of the diagnostic trouble codes exactly as they appear.

One method of isolating coil malfunctions is to swap the coil from a misfiring cylinder to a non-misfiring cylinder and see if the misfire code moves with the coil. I would suggest you do this before installing the new coils.

Have you looked down into your spark plug wells to see if oil is leaking onto the plugs?

Cheers,

Don