Can spark plugs cause misfire only under load?

[JSolo]

Could just be bad gas?

 

[MerlintheMad]

^^^Lol, "it's just gas". That's sort of what I was hoping to prove by revving, "Blow it out!" It's Costco premium, for what it's worth. Hah.

 

[G70LEbyAdoom]

Cost me only $20 at the pump for this 6 seconds.

Lol

It's the same in both neutral and park.

https://imgur.com/a/8iiELbJ

was it worth the science?

 

[MerlintheMad]

was it worth the science?

It was to me. I learned something new. Hey, I need to add this to the Interesting Discoveries Thread (Good or Bad) thread.

 

[MerlintheMad]

Update on my question: yes, it is okay to run with a CEL ON, since I am taking in the car for it in less than a week and there won't be any problem deriving from driving (conservatively, of course, doing my best to not push the turbos). I asked our mechanic just now, after giving him a rundown on the misadventures I've been battling since last October.

(edit: He's confident that Kia didn't replace the sparkplug boot when they replaced the cracked plug: and the boot gets corrosion on the inside when a plug misfires: you can't clean it off, you have to put on a new boot when you replace a cracked plug: at least I can sound like I know what I'm talking about next Monday when I go in for the diagnostic: and I will, of course, want to know if the problem is the same cylinder as last time: which will point to a bad boot, which will have ruined the new plug.)

 

[JSolo]

I think it's a bit more involved than just a "boot". COP (coil on plug) ignition is where the coil is part of the "boot". They'll likely have to replace that coil.

My guess is if they monitor parameters during a hard run, a cylinder (the one with the new plug?) will present different characteristics than others. IIrc, it's called inflight data.

 

[DoctorStiches]

^^^Lol, "it's just gas". That's sort of what I was hoping to prove by revving, "Blow it out!" It's Costco premium, for what it's worth. Hah.

Costco is flashy arco fuel sorry... no offence intended

 

[MerlintheMad]

Costco is flashy arco fuel sorry... no offence intended

Costco is supposed to be Top Tier.

This evening I drove for most of a couple of hours, mostly on the freeway, and the CEL stayed OFF: of course, I was trying to keep the turbos out of it, which I mostly succeeded in doing. So, the misfire doesn't happen under "civil" driving conditions, and I should make it till the diagnostic on Monday morning without any misadventures.

 

[JSolo]

Top tier or not, I think it's possible to get a bad batch at any gas station. Wonder if the premium these days is watered down more so than usual....

 

[bfglitch]

Bad gas since the beginning of January when his problems started?

 

[JSolo]

Well wait, before the issue was a cracked spark plug. I suppose it's possible it's another cracked plug but what are the chances.

 

[bfglitch]

The problem is the signs of bad gas and faulty plug(s) are fairly similar. The only one though that should go away with a fill up is bad gas. Unless he's constantly buying bad gas and using the low grade stuff, I would imagine it's not bad gas. Even if he is using low grade fuel, the car is supposed to be able to adjust for it and still run normal although not at top performance. My guess is the dealership did as little work as possible, pulled the boots, saw the one plug was cracked and swapped the one cracked plug and didn't bother checking anything else.

 

[MerlintheMad]

Well wait, before the issue was a cracked spark plug. I suppose it's possible it's another cracked plug but what are the chances.

Pretty high chance it's the same plug/cylinder. My mechanic said that if you don't change the boot too, that corrosion in the boot will ruin any replacement plug quickly. That fits the evidence: since I had the cracked plug changed in January and c. two weeks later the "chugging" returned, and cylinder operation has steadily declined, resulting in continuous roughness and CEL if I do any "spirited" driving/accelerating.

 

[DoctorStiches]

Costco is supposed to be Top Tier.

This evening I drove for most of a couple of hours, mostly on the freeway, and the CEL stayed OFF: of course, I was trying to keep the turbos out of it, which I mostly succeeded in doing. So, the misfire doesn't happen under "civil" driving conditions, and I should make it till the diagnostic on Monday morning without any misadventures.

I am just regurgitating the word around my locale

 

[MerlintheMad]

^^^What do you mean?

 

[DoctorStiches]

^^^What do you mean?

In south west washington the consensus is that costco fuel is so cheap because it is a mid level fuel with additives to help clean your engine. This upgrafes the 'quality' but the octaine is in question. And no i have not tested the quailty myself. And the only evidence i have is my stonger would missfire with costco fuel regularly untill i stopped using it. But we dont need to drag this dead horse around again just fuel up wherever you need to. Upgrade to denso or hks plugs and see if the problem goes away.

 

[DoctorStiches]

Also... the gap is still in question. .022 - .028 spark gap is the effective range in my mind

 

[MerlintheMad]

Just returned from Jerry Seiner, South Jordan: was there less than half an hour: and the resolution has to be postponed a couple or a few days. The reason originally was James (the service manager) called me before I left (but I didn't answer, thinking a Midvale call, which I get often, was a spam call: now I have his business card with the number, hah), and he was going to warn me that the technician that is certified on Stingers called in sick: but because I didn't answer the call I went in and got some joy: they scanned my car and got the info that cylinder six has a problem: that matches my service record from last time - cylinder six plug was changed. I told James that the boot needs replacing and he called to see if there was one in house: negative: and the parts guy told him that the coil pack and boot go together (thus confirming what @JSolo said about the coil and boot being a set): James looked in the dealership system and there is a boot/coil pack set, one, but he doesn't know if it is spoken for: he said he wanted it, and if it's mine, it goes in early Wednesday morning: if he has to order one, he said next Monday.

Meanwhile, on my way in, I did a (botched) launch from the light at 10000 South and Jerry Seiner Road: I did everything right except put it in Sport mode , which simply means you push the go pedal waiting for the "Launch is ready" (or whatever it says) popup: after a couple of seconds I just let off the brake and did WOT, which went well enough though was not impressive (go figure): no chugging or fluttering-hesitation this time, but the CEL light came on instantly, and went out just as instantly this time when I let off the gas.

 

[Daiquan23]

I'm having the same issues. Going to replace coils and plugs. Hopefully it fixes my problems.

Having the same issue.did that fix your problem

 

[MerlintheMad]

What did you do to your Kia Stinger today?

I'm here at Jerry Seiner, South Jordan, getting this done: the plug (aaagain) and this time the boot/coil. The first pic is from January 19th, when I was in here getting cylinder six's plug changed (it was only c. four months/4K miles old, after getting all plugs changed at c. 45K miles -...

stingerforum.org

The boot/coil set cost $100 apiece. So, replacing the "boot" at the same time as the plugs (a la my mechanic's recommendation) is not practical in this car. They are under the bumper-to-bumper, 60K miles/five year warranty: after that, when one goes south you have to pay for it. The "powertrain" warranty (taking us up to ten years/100K miles) only covers mechanical, non-electrical stuff.

I did six wholly satisfying launches today, with my body pressed back in the seat. Full power is restored (until the next time, heh).