Misfire Under Heavy Load Only

[KJMS3]

@Crazycanadian i have my catch can/PCV routed exactly like the CS instructions found here. As for the miss, I did have some mods to the car when it started, those being HPFP, the graveyard injectors, CS injector o rings and seals, CS 2.5” ram intake, CS 50/50 BOV, CS 80mm catback and test pipe, CS motor/trans mounts, and a tune on 30% ethanol blend from DramaTune (who I will now no longer be retuning to in the future). I had a 91 tune as well but always ran it on E30.

@Enki I got bored at work and pulled the oil cap off for the hell if it and got a vid, that’s attached here too but I also have a genwon. Shit made a mess but I knew that was gonna happen anyways lol.

So I can get a leak down tester early next week and do that as well and come back with the results, I would this weekend but I’ll be out of town leaving tonight. I agree with Canadian tho, it sounds and feels like an electrical/ignition issue when driving, I would think a lean condition from failing injectors would show on the datalogs right? If the leak down comes back okay then I can get a set of good coils from one of my other ms3 homies and try those.

When I was researching mods and tuners to use with these cars when I first got mine, I never saw anything about drama or graveyard being bad, must’ve just not looked hard enough. Everything I saw said go to drama or PD, and I just picked drama out of a 50/50 basically.
View attachment IMG_1147.mov

 

[Enki]

The problem with Drama is that if you're researching via Facebook you can't see the censorship that happens. I've heard many stories about people having even questions that could be construed as negative being removed, along with their presence from said group shortly thereafter. Dude runs a cult, basically.

That does look like a lot of air coming out of the valve cover, but the sheer weight of the oil could be at play here too. Hard to tell unless you're certain you felt and smelled a lot of hot smoky air coming out of there. Should smell somewhat like oily exhaust if memory serves.

 

[KJMS3]

To me it smelled like any other car when you take the cap off while it’s running, and no smoke or anything like that. Though I have noticed sometimes when topping off the oil after driving, and letting it sit for maybe 10ish mins before adding my oil, there will be a very small, faint amount of smoke that comes out of the cap while I’m pouring the oil in, not when I just take off the cap. Can barely see it but when the sun hits it right I can barely tell it’s there (it leaks bad rn but I check it twice a week and make sure it’s always full). The air coming out in that vid felt pretty moist with oil but that’s probably bc of the oil literally spraying out of it that you can see too. But it didn’t smell like if oil was in an exhaust/burning.

And yes my research was through Facebook so that makes a lot more sense why I saw his name so much.

 

[Easter Bunny]

Where did you get the plugs? People have gotten fakes from Amazon.

Do you still have your old coil packs?

Check all of the wiring to the ignition coils.

I would seriously doubt that all the coils are bad. The misfire would only be on one cylinder if a coil was bad.

@Crazycanadian I don't believe I have ever heard of someone breaking a valve spring but someone can always be first

 

[Enki]

I hadn't considered fake plugs but yes, that is a very valid consideration. I had just seen a thing on youtube about this a while back too.

Fake edit:
Found it

 

[KJMS3]

No I get my plugs from o’reilleys, I hope they’re not selling fakes lol. No I don’t have my oil coil packs anymore, I tossed them when I got the new ones. When I get that leak down tester and do that next week probably on Tuesday, I’ll take a look at the wiring harness to the coils and see if there’s anything that looks peculiar. I think I recall seeing a thread on here about people having bad coil harnesses a while back, never really crossed my mind for some reason

 

[Crazycanadian]

Where did you get the plugs? People have gotten fakes from Amazon.

Do you still have your old coil packs?

Check all of the wiring to the ignition coils.

I would seriously doubt that all the coils are bad. The misfire would only be on one cylinder if a coil was bad.

@Crazycanadian I don't believe I have ever heard of someone breaking a valve spring but someone can always be first

I haven't heard of it happening in this platform. But I've seen it in GM's, Dodges, VW and Audi's... The last one I saw was in a 2010 2.0L turbo Golf.. The spring broke, the valve dropped, kissed the piston just the right way in order to jam it closed.. since it's like our heads with 2 valves per cylinder it ran and drove great. It would throw cylinder 4 misfire codes, only under heavy throttle when climbing a hill... This motor passed compression tests, leak down tests, you name it... It was wild..

 

[Easter Bunny]

Those four brands are notorious for finding creative ways to break though

 

[Enki]

Those are the kinds of brands that weigh wiring harnesses to make sure they aren't shipping too much wire/sheathing

 

[KJMS3]

Would’ve had this posted yesterday but weather didn’t permit me to work. Just finished up with the leak down test and it ain’t looking good unfortunately. All cylinders tested about 3-4% leak down except cylinder 3 at about 18%. Pic and vid attached

While taking out the plug for Cyl 3, the porcelain somehow broke on the damn thing so I had to get another, only got one bc fuck it, but it somehow helped the miss by getting that new plug in there, now it makes a little more boost before misfiring lol. Figured that’s worth mentioning too.
View attachment IMG_1169.mov

 

[Easter Bunny]

1 did you get the broken porcelain out of the cylinder
2 seems like you have a bad or fake set of plugs i would replace all 4. where did you get them from?

 

[KJMS3]

Got the plugs from O’Reillys, and yeah all the porcelain stayed in the socket so it didn’t get down into the cylinder.

 

[Crazycanadian]

It's not great, but it's also not your misfire issue.. I've seen motors worse then that without a misfire issue, including the original motor in my speed 6..

That kind of issue can cause what I'll call a "soft" misfire that most people don't notice. When a soft misfire you get some combustion happening. It's not a completely dead cylinder. It normally happens at idle and mostly during cold start up. Dirty injectors with poor spray pattern generally causes a soft misfire as well. An injector has to get pretty bad before it'll cause a hard misfire

The misfire in your video is a "hard" misfire. A hard misfire is zero combustion, or totally out of time. A hard misfire shakes the car. If it's there at idle, you have a dead cylinder. Other then that, this type of misfire shows up under load.... Engine load is something that people don't fully understand either, but that's a different topic. A hard misfire is a spark plug issue, bad coil, or coil boot, wiring issue, ECU driver issue, Crank/cam signal issue causing ignition timing to jump around... ECU, Crank/Cam signal stuff isn't common on this platform.. Coils aren't super common like a Ford.. OEM mazda coils work well. These cars are getting old enough now where the wiring harnesses are getting a little crusty. The motors shake enough that it can cause poor connections that'll drop out an injector or coil.

You want to fix this misfire before you pull your hair out throwing money at everything.

 

[KJMS3]

Ok well that sounds like some goodish news that at least my motor may not be shitting the bed. But yeah it’s been a long almost 8 months now of chasing this miss and I’m starting to lose it lol. I’m at a point where I wanna be done throwing money at this and I don’t wanna take it to a shop that’s gonna charge me an arm and a leg just to diagnose it. Plus I have another build that I need to finish so I’ve begun focusing on that more with my finances now so I can get that car done. I just really don’t wanna give up on this car if I can help it.

I’m thinking it must be a wiring issue then because I’ve replaced damn near everything you just mentioned (ECU, plugs multiple times, coils), and I would think a cam/crank sensor issue would throw a code for that part? Plus it’s a pretty high mileage motor with it just crossing 212k miles this week, so yes my harness is quite crusty from all that run time this motor has had. The thing with is being electrical is I’m almost useless with wiring shit. Any advice on what to be looking for on the harness and connections? Is there a way to test the harness for something like that? Is there a specific part or area on the harness I should be checking?

 

[Crazycanadian]

This is the kind of problem, you aren't likely to find by looking at things and taking it apart... You've been in and out of there a few times and nothing obvious has shown it's head.. You need a buddies car you can rob parts from or swap back and forth at this point.. Otherwise it's someone with a Pico Lab scope and the knowledge on how to use it to watch signals while driving to see if or what drops out.. That doesn't come cheap...

If I was gonna throw more parts at it.. I'd probably try and injector harness since it'll get the most crusty considering where it lives

I would agree a cam/crank problem should cause a code..