2012 MS3 Stuttering Under Load (Logs)

cbrandxn

cbrandxn

Greenie N00B Member
SOLVED

Year/Make/Model: 2012 Mazdaspeed 3
Mileage: 150,000 kms / 93,000 miles
Location: Ontario, Canada
Concern: Motor sputtering/misfiring under load near/in peak boost
DTC's: P0300 Multiple/Random Misfires Detected, P0302 Cylinder 2 Misfire Detected, P0403 (EGR Delete)
Modifications: Cobb AP v3, Cobb SR Intake, Cobb Turbo Inlet, Forge BPV, Autotech HPFP, JBR 80A RMM, Corksport Catback (No Muffler)
ECU/Tuning Software: AP v3
Tuner: Cobb OTS Stage 1+
Is the concern intermittent?: Yes
Can you duplicate the concern?: Yes
Recent Repairs:
- Coil packs replaced with OEM, spark plugs inspected and cleaned, compression tested at 135,000 kms (Cyl 1 180, Cyl 2 180, Cyl 3 185. Cyl 4 165)

Within the last week (Sept 20) in the morning while driving, I gassed it in third to drive thru a yellow, but by the time i got to the other side of the light, the car was violently shaking and the motor seemed to be choking with audible misfiring, CEL started flashing during the shaking then remained solid (EGR) after the shaking. This is my first instance of this occurring ever, and first motor issue overall. It was around 12 C (53 F) in the morning when this occurred. Around noon, I tried to replicate this issue cause I figured maybe it was temperature related in the morning, and couldnt replicate it. Around 4 pm I was able to replicate the issue, but it seemed that the severity in shaking dwindled a bit. The next day I replicated the issue again (26 C, 78 F), but this time it seems to shake alot less violently and my CEL didn't flash, but the stuttering had still occurred toward the latter end. I have had small amount of hesitation in power between shifts since then, but not very often. I've ruled out any boost leaks as im still able to maintain boost during a pull, originally thought it was the EBCS or hoses, but they all seem to be in good condition still. Im just puzzled as to where to go with diagnosing this. Thought it was motor mount or boost leak originally, but my current suspects are that my spark plugs are fouled, or may need to be changed (last change was at 110,000 kms, 4 years ago, gapped to 0.028), or maybe something MAF related? PMM to be replaced soon as well. Will look into these during the upcoming weekend. Not the greatest at reading logs adequately, but the log attached is me replicating the scenario where this instance occurred in the first place. (Cell 624 to 655)
Thanks in advance lads.
 

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Seeing 1.8 load; that might be a touch high for a stage 1 tune on stock K04, but it's been ages so I don't remember.
Also, cold air is gonna increase your airflow a bunch, which could explain the bucking (possible load related fuel cut or potentially spark blowout, but that seems somewhat unlikely). This is supported by seeing the boost come up to 15 PSI then immediately falling back down to 12 PSI, but what's odd is the WGDC doesn't really change, so not entirely sure what's going on here.

Did anything change just prior to having this issue?

What fuel are you running? Also, tighten that gap to .026, IIRC that's what most people run and it won't hurt anything, plus it only costs time to test.

A last thought suggests that the low compression on 4 might be a result of busted ringlands, and combined with the stock PCV setup, that can cause the car to run like a turd in general; though, if it cruises just fine and the issue happens only under boost, not real sure what's up.

In the future, make sure to log Accel Pedal Position, as the throttle and pedal are not 1:1 and can vary; we need to see what YOU are telling the engine to do, not only what the engine is doing. Also, keep it as a CSV file, unmodded as not everyone has Excel.
 
Prior to this issue I changed nothing recently, and recent is within the last 10k kms. This issue is like a random issue that happened overnight I guess. The issue does only occur when in boost, at different psi ranges, but within the 9-16 psi range. Other than that, it cruises in every gear pretty smoothly. Im running 91 on the Stage 1+ Cobb OTS map.

Yesterday I inspected the plugs again, some whitening with gaps ranging between 0.028 and 0.029. Someone on reddit mentioned how my plugs were probably overdue at 40k kms so i've already ordered new ones to maybe cut out a variable (NGK LTR6IX-11 (6509)),. I have also noticed the slight hiccup/stutter sometimes on light acceleration within the last day or two so definitely needs to be done.

I compression tested the cylinders yesterday. That original 165 may have been just from poorly reading the gauge or sealing of the hose and mind that this reading was from 2 years ago roughly. My new numbers are Cyl 1: 172, Cyl 2: 176, Cyl 3: 180, Cyl 4: 175.
Forgot to mention I do have a Damond OCC, but not too sure if that affects anything.

I'll log some more data tonight and follow up later. Gonna go again in third again and hold it a bit longer to try and get some more extensive data. In the initial logs, I did let off the accel a little fast only cause of how much would shake. I'll change the log parameters as well, which honestly, I forgot that was even a thing. And keep it as CSV, got it.
 
I thought the whole point of iridium plugs was that they last forever...

Anywho, disassemble your Damond OCC setup and clean/lube the check valves, and reinstall.
 
Iridium plugs do last forever.....
Hope that part number is stock heat range

Swap the no 2 coil pack and see if the misfire stays on 2 or follows the coil
 
Eh, relatively cheap to replace so I dont mind. I dont know if it makes a difference but I do alot of short driving trips, an average day is max 20-30 kms a day round trip. I'll take a look at the OCC over the weekend. I logged a bit more data and added Accel Pos. The 3rdaccel file corresponds with the video.
 

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The part number is stock heat range, I referenced an old post from Awafrican. I'll swap over the coil to see if it follows.
 
Yeah you need to get the engine hot (most importantly, the oil) so it can clean itself up. Not sure that 30 KM a day is gonna cut it, tbh.

If your oil winds up diluted with fuel (you can sniff the dipstick to confirm), the vapors may bleed over into the intake via PCV and cause some minor fueling issues (generally only at idle and cruise though).

Will check the logs later.
 
Logs look pretty normal, and the 6th gear cruising log has trims basically on point.
I don't really *see* anything wrong, but the video kind of reminds me of this:

https://www.youtube.com/shorts/UUM8g7VXBHQ

Basically, it sounds like you're down a cylinder when you try to give it gas. Not real sure what's up with that.

Might need to borescope the cylinders and make sure everything looks good inside, unless you stumble upon some kind of weird exhaust leak or something.
 
That’s where i’m stuck right now. Any suggestions as to what to look for when I put my borescope in besides the piston heads? I’m also thinking maybe it’s something to do with the tune? Unfortunate timing cause I wanted to throw on my downpipe sometime soon and get it freektuned but the car is upset I guess lol.
 
Valves, cylinder walls to look for scoring/abrasions from possible broken ringland(s).

Could also check to see if you have a lot of PCV flow if that's easier for you; if you have a ton of it, that means the rings aren't sealing or you have a busted ringland.
 
Will definitely take a day this weekend to take a look at everything you've mentioned. I am leaning towards something to do with the PCV or the OCC check valve as well now, but checking inside the cylinders won't hurt either. I'll check the flow through the hose that connects to the valve cause damn I hate playing with that valve. I do feel the car is running a bit rougher now than it was earlier in the week.

I cleared all codes before heading home today and did a few pulls. Weirdly enough my misfire codes never showed up again. Doing the same 3rd gear pull seemed to have gotten better, it no longer had that weird stuttering like in the video from before, and now it seems to be just a quick 1 or 2, half second hiccup when in boost with a slight KR of like 0.3-0.5.
 
Swap coil packs like Buns suggested above first. It's super easy to do; just swap 2 and 3 and see if you get a misfire on 3 instead of 2 this time. If you do, that coil is dying.
 
If it won't throw a code you might need to buy one new coil pack. I know that my car basically won't throw a misfire code ever so its tough to troubleshoot
 
Ok, sounds good. I’ll swap them tonight and see what happens from there. Honestly never thought that OEM coils from the dealer would die this quick.
 
Could be the wiring harness. @Awafrican had a lin get bent and not insert all the way that gave him hell for a while so look at the harness and plugs while you are there
 
Easter Bunny said:
Could be the wiring harness. @Awafrican had a lin get bent and not insert all the way that gave him hell for a while so look at the harness and plugs while you are there
Click to expand...
the pins being bent was from test leads on the fuel injector during cleaning. I didn't check to make sure it was straight when I got them back and connected the harness (clicked and everything) and had no fuel from that injector.
unlikely that's the issue if no recent work (10k km before issues popped up per op) still worth a quick inspection.

OP when you get those plugs gap them to 0.026"-0.028", agreed swap the coil packs around and see if it happens.

id also clean the maf sensor, how's that engine air filter looking?
 
Didn’t get a chance to do any work tonight. Plugs should hopefully be delivered tomorrow. Will swap the coils then, probably gonna gap the plugs to 0.026. Doesn’t hurt to check the pins either.

Yup, agreed, maf sensor cleaning was on that list for tomorrow. The filter could definitely use a cleaning I know that.
 
Could also just rotate the filter and see if behavior changes. If the color is different on just one side, that would suggest a new filter is a good idea though.
 
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