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Zalvern

Tale of a Spark Plug

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So had a lovely discovery upon doing some tweaking to my MKZ. I got ahold of some MSD Coil on plugs "upgrades" to try out on the 3.0T engine. Like many other 2.7L modification options, the coil packs do work and simply help keep spark power high without needing to reduce the gap when under high boost pressure (my MKZ is pushing almost 40 psi at the sensor, which is combined boost reading).

 

I decided to change the Spark plugs too, even though they're only around 17,000 miles of use. Peace of mind and I can see how my plugs are doing since I've been using ACES IV and Livernois' tune.

 

Well 5 plugs come out perfect. By far best I seen compared to my "pig rich" Fusion. I also definitely do not need colder plugs or smaller gaps, as these are really great condition reads. I give my thanks to ACES IV as it aims to create the perfect combustion process.

 

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But the 6th plug, which was in Cylinder 4, come out with some bad news:

 

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It's got ash deposits and is wet around the center electrode. It's soaked in fuel.

 

At first I worried about the oil leak TSB due to bad 2.7L/3.0T cylinder heads for vehicles during a certain production time frame, but the plug appearance indictates no oil contamination. The plug still fires but is far weaker than the others.

 

This plug is the reason for mini misfires and shift lags. It fools me really well however because it does not power lag all the time.

 

Bad plug is sadly not the case. My newest plug that was placed in to Cylinder 4 has fouled out within 2 days. Its been predetermined to be a faulty fuel injector. I've been with this faulty injector since taking delievery of the car.

 

So back to the dealership it will go. I shouldn't need anything (hopefully) drastic like a new engine. Just fixing the fuel system and probably gain back power and fuel economy I've been missing out on this entire time.

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I am happy to see all is well with the tune. Does the faulty injector also show by throwing a code?

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Nope there is no obvious DTC or CEL for this kinda of problem. Only warning is irregular performance and declined fuel economy. The injector is functioning when it is operating (it is getting correct voltage readings), but the problem is its failing to hold pressure upon shutting down the car. Excess fuel gets dumped into the cylinder chamber and douses the spark plug. Its also believed the injector is just using too much fuel at inappropriate times. The spark plug still works too but is very unreliable especially at higher performance loads.

 

Explains why the car shifts harshy after I start it up and it begins shifting. Over time it will shift smooth, but minor misfire may happen randomly. I did have two times in the past I got full flashing CEL on the dash with codes on Cylinder 6 (not 4), but it corrected itself. Under high loads the 2nd to 3rd gear really drags and I clock like 5.0+ seconds in 0 to 60 momemts, with a Livy tune...and I know thats not its full potential.

 

Will know more after Tuesday.

Edited by Zalvern

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The dealer doesn't have an issue with your mods and warranty work on the engine? 

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I guess the bright side is you have too much fuel. That's better than running lean and detenonating a hole in the block.

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Yes, better to be running rich than lean. No problem with bolt-on modifications, as the most important thing is they're reversible and unrelated to the issue at hand. The only thing that could possibly mess up a fuel injector would be a PCM tune, however if that was the case the tune would have ruined all of the injectors, not just one. ACES IV gasoline formula is also ruled out because the other 5 plugs were in excellent condition, and if it was the culprit, all the spark plugs would of shown issues.

 

I will revert to stock tune not because I am trying to hide it, but getting a new fuel injector may require re-calibration of the fuel control within the PCM. This may change my Strategy code which Livernois may need to update on.a

 

Time for another loaner...maybe I'll get a Continental this time. It's nice the dealerships let me pick a loaner if they have multiple available.

 

EDIT: Continental was barebones and non turbo V6. Went with the Black Label MKC instead.

Edited by Zalvern

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Final Update: MKZ passed all engine compression and balancing tests. It is really running excellent as the Lincoln service techs have checked out, and said it couldn't be any healthier. 2nd set of spark plugs are not fouled, so the one plug must really have been a bad core. What was discovered is my battery's case was cracked and leaking! An XS Power battery to boot, who claims their batteries are un-spill able. Luckily because I must have one of the rare defects...XS Power is refunding the cost for my XS Power battery (as of course Lincoln dealer sold me a new Ford Max battery to replace). Downside is I barely can fit my Steeda CAI with the stock size battery...but it works at least.

 

The car has mini misfires simply due to...its heat on intake air. Go figure, another reason to crave stuffing in C-PE's upcoming Fusion Sport Intercooler.

 

On days when it isn't humid or 85+ degrees of hot air...I get insanely nice and crisp shifts.

Edited by Zalvern

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Yes.  Heat really affects this car.  I've noticed a real drop-off in performance on hot days with the A/C on, especially at low speeds when you get on it; momentary stumbling.  It cooled down the last few days and I was able to shut off the A/C.  What a difference!  It must be throwing off so much heat around the IC.

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Of course this issue can happen if "too much oil" is put into the car. Thanks dealership! I let them change my oil as Black Label gets 4 free oil change services. Sigh...too much oil will pressure it's way out the PCV even if seals are strong. This is why only one cylinder was having an issue.

 

In the end dealerships weren't able to fix this problem. I did. Checking my dipstick definitely told me I wasn't seriously losing oil, and now I know why.

 

Will do my own oil changes from now on since we need an easily measured 6 quarts. No more and no less. Keep that in mind folks which is sad as we should be trusting these services...But nowadays I'm always weary.

Edited by Zalvern

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