mcypert

Hi All:

I have a CEL that came on. Code is P0300 (N92/2), Left bank ignition coil misfire.

Attached is a snapshot of the "current signals" for the left bank, and the right for comparison.

I'm assuming 0.06 on 8b is too low???? Although 11a is only 0.33, however the right bank (no codes for it) is as low as 0.81... Anybody know if this indicates coil, spark plugs or something else???

Car's at 65000 miles. I think the 2007 has iridium plugs and those shouldn't be bad at that mileage...Right??? Car had 40000 mile dealer service but I don't think that includes spark plugs. So, I'm guessing these are the plugs it was born with??? Any thoughts on whether they need replacing at 65K????

If it is the coils (my best guess), has anybody had any experience with http://www.v12icpack.com/ ??? I think they rebuilt for $700. New is about $900 unless someone has found a better deal. But v12icpack will ship your's back if it's not bad and charge you $125...

Any advice is appreciated.... Thanks...Mark

ItalianJoe1

Plugs are serviced at 60k on the v12. Change the plugs and see what happens.

Does it misfire under load? At startup/idle? When does the code set?

mcypert

Thanks Joe:

I can't detect any misfire... Feels like full power to me.

Code does not set at idle. Only set twice so I really wasn't looking, but suspect it happened under medium throttle.

And, you are indeed correct Spark plugs at 60K... I missed that. In that regard, can I count on the recommended plug? Or, do I need to take one out to match the numbers exactly?

Regards...Mark

alx

Those codes can be both coils or plugs. Specifically Inspect cylinder plugs 8,11 and 12. Replace plugs as they are due at 60k miles anyway. You want the exact oem plugs for your car. Exact ones. If that doesn't fix issue then it is coil time.

My guess is left bank coil pack is bad and your plugs are good.

mcypert

Thanks Alx:

So reading between the lines, we can't really tell anything from the STAR current data... Correct???

Regards....Mark

alx

Read my last sentence. Since bad ignition voltages are on one side I suspect coil pack.

mcypert

I'm still confused on what the "Ionic current signal" in the Star readings in the pictures above is telling me???

I've had some correspondence with the guy who repairs the coil packs. If I understood correctly, it's a low voltage signal used to detect unburned fuel???

What I don't know is if the data tells me anything about which cylinder, plug or coil might be misfiring???? The P0300 code just means a random misfire and doesn't indicate which cylinder.

Can anyone tell me what these voltage readings are there for? And, are they useful in diagnosing the P0300 code?

There is consensus that the plugs should be replaced regardless... I'll start there...

Thanks again...Mark

alx

https://www.google.com/patents/US6211680

the ionic signal voltage you are seeing is a simplified value (sum, average? they dont tell you) provided by the "integrator". higher values essentially denote good ignition cycle (timing and spark strength - wise) while low values denote timing or spark strength problem. your 8,11 and 12 cylinders are not firing correctly. my experience tells me it is either plugs (which are due anyway) or ignition coil (check serial number to see if you have older version if you do - that is most likely the problem). less likely it is coil controller and least likely a plugged cat on that side of the engine.

mcypert

Now that makes sense.... Thanks ALX...

mcypert

One more follow up...

I'm in Houston. Drove downtown and back after clearing CEL P0300, about 25 miles round-trip, nothing over 75 mph and nothing over about 3000 rpm on accel. No CEL for the trip...

Does that indicate anything about whether it's coil or plugs?

The reason I ask is: I'm going to replace the plugs anyway. But, since I'll have the coils out, I'd rather send them in for testing and/or repair than pull them again, if it's probably the coils... If it's probably the plugs, I'll risk doing the job twice... I leaning towards plugs only for the first try...

Thoughts??? ...Regards...Mark

DaveW68

If it drives fine under normal acceleration....then goes into limp mode if you hammer the gas, you have a bad coil pack on one side. Fortunately all you have to do is stop and re-start the car to take it out of limp mode.

mcypert

Thanks Dave:

It's never gone into limp mode. In fact, I can't hear or feel any misfire (of course what's one cylinder among 12). The only notice I get is the CEL; that's lit twice.

Drove around town again today. CEL has not returned. Next week, we'll be making the 350 mile trip home... I'll just drive easy, nothing much over 80 mph...and see what happens...

Regards.... Mark

alx

as i said- since all your misfires are on one side it is probably the coil pack. it could be also a clogged cat, but those manifest themselves as more severe misfire and general driveability problems.

alexanderfoti

+1 on coil pack, classic symptoms.

mcypert

Got it guys...Thanks...

Now I have to decide; do I want to do plugs and coil pack at the same time, or double the time under the hood by trying only plugs first???

Regards...Mark

DaveW68

If your car still has the original coil packs after all of these years and miles, then you've done better than most on your S600. Supposedly the new part number, which came out somewhere around 2009 or 10 is a better build and shouldn't fail. My S600 is already on its 2nd replacement of coil packs. The first ones (both sides) were replaced prior to 10k miles with the original part numbers (while the original owner had the car). One of those coil packs failed around 32k miles IIRC under my ownership and was replaced with the new part number. I've been waiting for the other shoe to fall with the other bank, but 10k miles later and it still hasn't failed. Fortunately my warranty will cover it when it does go, as they are expensive to replace. I'm not sure if having them rebuilt will make them any more stout than what the original part was when it came from the factory.

mcypert

Thanks Dave... That helps in the decision tree...

Your observation/ history prompted me to look at my Carfax again to see if either coil had been replaced... (Pretty good dealer service records there.)... No coil replacement... But, guess what, spark plugs at 42,600 miles on 50K service!

Those plugs shouldn't be bad at 23,000 miles of use...Right???

So, I guess I have my answer... COIL PACK...

Now, the decision is do I do spark plugs anyway?... I'm leaning towards NOT...

Again, thanks for all the input. The responses have narrowed my quandary considerably....Mark

DaveW68

If you have the coil pack replaced, you might as well have the spark plugs replaced too (on that bank) while they're already in there. Spark plugs are cheap, especially if you order them. You can find them on Ebay for less than half of what the dealer will charge you for them. But if the dealer is doing the service, you likely won't have a choice. 12 spark plugs per bank.

I believe the first major service on these cars is due at 4 years or 40k miles, so yours was done at the appropriate mileage. My 40k service was done at 20k miles due to time. The previous owner only put around 3k miles per year on it.

mcypert

Thanks Dave...

I'm doing the work... And, as a lawyer/engineer my time is considerably cheaper than a dealer tech... just kidding... I do it because I enjoy it and can only blame myself if it's done wrong.., Not to mention dealer is 50 miles away..

And you're right, spark plugs are cheap, relatively speaking... But, if I replace one side, then why not the other and so on...

At less than half the service life, and probably more miles left than I'll keep the car, I'd conclude: Unnecessary... Kind of like changing the oil every 3000 miles... I drive a gas-hog V12, but still believe in conservation...

Unless someone thinks the plugs were somehow damaged because of the random misfire, as said, I'm leaning towards Not replacing the plugs... On the other hand, I might be needlessly replacing a $900 coil pack... And, may wind up replacing the plugs anyway... I make dumb decisions everyday... Just ask my wife...

I've thought coil pack the whole time... except when I thought plugs...duh... But, this forum is kind of like the "Who Wants to be a Millionaire" audience , they're usually right...

Regards...Mark

PS... I'm going to check with the dealer who has my VIN to verify what's been replaced...