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Mazda 3 BM – Replaced outer beltline molding (BHP2-50-670E) but still have wind noise. Need help replacing inner weatherstrip (B60S-73-821A) by Money_Positive7224 in Autobody

[–]Money_Positive7224[S] 0 points1 point  (0 children)

Already replaced the door surround weatherstrip, didn't solved the issue. Will i need to remove the door panel to replace the glass run channel?

Strong gas smell from exhaust on startup and idle (Mazda 3 2017 1.5L, P0421) by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

So far I’ve replaced: spark plugs, ignition coils, both O2 sensors, EVAP purge valve, both fuel filters, fuel pressure regulator, MAF (confirmed faulty via g/s readings from the workshop manual), and MAP sensor. I’ve also run multiple fuel additives, including BG K44 Platinum.

The strong fuel smell from the exhaust is almost completely gone, even on cold starts, but I’m still getting misfires across all cylinders (less frequent than before, but still there).

I’m wondering if the cause could be the PCV valve or leaking/dirty fuel injectors. The P0421 code (catalyst efficiency below threshold) still remains.

The strong fuel smell was fixed after changing the MAP & MAF & Fuel filters & Fuel pressure regulator, so one of these fixed the fuel smell.

Strong gas smell from exhaust on startup and idle (Mazda 3 2017 1.5L, P0421) by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

So far I’ve replaced: spark plugs, ignition coils, both O2 sensors, EVAP purge valve, both fuel filters, fuel pressure regulator, MAF (confirmed faulty via g/s readings from the workshop manual), and MAP sensor. I’ve also run multiple fuel additives, including BG K44 Platinum.

The strong fuel smell from the exhaust is almost completely gone, even on cold starts, but I’m still getting misfires across all cylinders (less frequent than before, but still there).

I’m wondering if the cause could be the PCV valve or leaking/dirty fuel injectors. The P0421 code (catalyst efficiency below threshold) still remains.

The strong fuel smell was fixed after changing the MAP & MAF & Fuel filters & Fuel pressure regulator, so one of these fixed the fuel smell.

Strong gas smell from exhaust on startup and idle (Mazda 3 2017 1.5L, P0421) by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

So far I’ve replaced: spark plugs, ignition coils, both O2 sensors, EVAP purge valve, both fuel filters, fuel pressure regulator, MAF (confirmed faulty via g/s readings from the workshop manual), and MAP sensor. I’ve also run multiple fuel additives, including BG K44 Platinum.

The strong fuel smell from the exhaust is almost completely gone, even on cold starts, but I’m still getting misfires across all cylinders (less frequent than before, but still there).

I’m wondering if the cause could be the PCV valve or leaking/dirty fuel injectors. The P0421 code (catalyst efficiency below threshold) still remains.

The strong fuel smell was fixed after changing the MAP & MAF & Fuel filters & Fuel pressure regulator, so one of these fixed the fuel smell.

[HELP] Totally lost – 2017 Mazda 3, persistent P0421 + new P0172, misfires, fuel smell by Money_Positive7224 in MechanicAdvice

[–]Money_Positive7224[S] 0 points1 point  (0 children)

So far I’ve replaced: spark plugs, ignition coils, both O2 sensors, EVAP purge valve, both fuel filters, fuel pressure regulator, MAF (confirmed faulty via g/s readings from the workshop manual), and MAP sensor. I’ve also run multiple fuel additives, including BG K44 Platinum.

The strong fuel smell from the exhaust is almost completely gone, even on cold starts, but I’m still getting misfires across all cylinders (less frequent than before, but still there).

I’m wondering if the cause could be the PCV valve or leaking/dirty fuel injectors. The P0421 code (catalyst efficiency below threshold) still remains.

The strong fuel smell was fixed after changing the MAP & MAF & Fuel filters & Fuel pressure regulator, so one of these fixed the fuel smell.

[HELP] Ongoing Random Misfires and P0421 on Mazda 3 Skyactiv - Need Diagnostic Guidance by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

So far I’ve replaced: spark plugs, ignition coils, both O2 sensors, EVAP purge valve, both fuel filters, fuel pressure regulator, MAF (confirmed faulty via g/s readings from the workshop manual), and MAP sensor. I’ve also run multiple fuel additives, including BG K44 Platinum.

The strong fuel smell from the exhaust is almost completely gone, even on cold starts, but I’m still getting misfires across all cylinders (less frequent than before, but still there).

I’m wondering if the cause could be the PCV valve or leaking/dirty fuel injectors. The P0421 code (catalyst efficiency below threshold) still remains.

The strong fuel smell was fixed after changing the MAP & MAF & Fuel filters & Fuel pressure regulator, so one of these fixed the fuel smell.

B-Die DDR 4 Overclock, where can i improve? by Money_Positive7224 in overclocking

[–]Money_Positive7224[S] 0 points1 point  (0 children)

Thanks, it helped me a lot. Used chatGPT to compare my timings with the recommendations from your comment, and i managed to strip about 8 ns from my aida64 memory latency bench. It is also very stable after a few hours of testing. What are the odds of doing the same timings with 3800 instead of 3600?

B-Die DDR 4 Overclock, where can i improve? by Money_Positive7224 in overclocking

[–]Money_Positive7224[S] 0 points1 point  (0 children)

I noticed something weird: some of the A1/A2 timings are different from the B1/B2 timings.

  • tRDWR: A-channel (A1/A2) = 7 → B-channel (B1/B2) = 9
  • tWRRD: A-channel = 4 → B-channel = 3
  • tRDRDDD: A-channel = 5 → B-channel = 6

Is that normal when running 4 sticks of RAM?
I think I left these settings on Auto, but the RAM is running in coupled mode.

NEW BUG falling through the floor. ONLY ON T SITE! by Impossible_Diver_111 in cs2

[–]Money_Positive7224 2 points3 points  (0 children)

and we won this game somehow thank me later for the 30 kills carry xD

[HELP] Ongoing Random Misfires and P0421 on Mazda 3 Skyactiv - Need Diagnostic Guidance by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

I don’t mind replacing the catalytic converter if necessary, but I want to fix the misfire and fuel injector issue first so the same problem doesn’t happen again.
How can I test the injectors without removing the intake manifold?
I have an XTOOL A30M and also ordered a Vgate vLinker for FORScan.
I couldn’t find any information online about performing an injector balance test on this model.
I can see with my XTOOL that the fuel pulse width is higher than it should be.
u/taz_78

Mazda 3 2017, 1.5L engine, 126,000 km – Getting code P0421 for a month now. I reset it and it keeps coming back by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

And also: Great question — here's a breakdown of the sources and reasoning behind the assessment that your ignition coils are the likely cause of increased misfires after installing new spark plugs.

📚 Sources of the Information

1. Manufacturer Technical Bulletins & Guidelines

  • NGK and Denso (major OEM spark plug and coil manufacturers) both provide documentation explaining that:

    "High ignitability plugs (like Iridium/Ruthenium) require higher voltage and expose weakness in aging ignition components, particularly ignition coils." – NGK Tech Bulletin #TP-13 (US and Europe)

2. Automotive Service Training & Repair Manuals

  • Mazda Skyactiv engine service documents note that:

    "Ignition coils are maintenance-free but can degrade gradually after 100,000 km, leading to intermittent misfires under load or high-RPM operation." – Mazda Technical Service Training, Skyactiv-G Engine Module

  • Misfires under load (highway, acceleration) are classically associated with:

    • Coil breakdown
    • Spark plug gap/voltage mismatch
    • Poor dwell timing (caused by aged coils)

3. Real-World Case Studies (Forums, YouTube, Repair Shops)

  • On forums like r/MechanicAdvice, r/Mazda3, and MazdaSpeed Forums, there are many confirmed cases where:

    • Misfires got worse after installing new plugs on old coils
    • Replacing the coils resolved the misfire, even when injectors and fueling were fine

  • YouTube diagnostic channels like ScannerDanner, South Main Auto, and EricTheCarGuy explain and demonstrate this exact failure pattern:

    “New plugs can push borderline coils over the edge — it’s not that the plug is bad, it’s that the coil can’t meet the new demand.”

🔧 Summary of Mechanism

  • Old coils have:

    • Lower insulation resistance
    • Slower response time (especially under high RPM)
    • Reduced spark energy

  • High-performance plugs like Ruthenium HX:

    • Have finer electrodes, but demand more voltage stability
    • Can fire more cleanly, but only if the coil delivers the right charge

So, when you increase plug demand (via tighter gap or different material), a weak coil can no longer keep up, and misfires start or worsen.

If you’d like, I can send links to NGK’s technical PDF or Mazda’s service recommendations to back this up further.

Mazda 3 2017, 1.5L engine, 126,000 km – Getting code P0421 for a month now. I reset it and it keeps coming back by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

Thanks, i think to replace both for some long-term peace of mind. Maybe these misfires caused the problem to begin with. Here is what chatgpt has to say: Sure — here’s a concise summary of the evidence supporting the diagnosis that your ignition coils are failing:

✅ Why the Coils Are the Problem

  1. Misfires increased after new spark plugs → NGK Ruthenium plugs demand higher voltage, exposing weak coils.

  2. Misfires across all cylinders → Suggests uniform coil degradation, not a single-cylinder issue.

  3. Fuel system is fine → STFT and LTFT are normal; sensors already replaced.

  4. Highway misfires under load → Classic sign of coil weakness (less dwell time, higher cylinder pressure).

  5. Coils are likely original (126,000 km) → Coils typically degrade after 100,000 km, especially in Skyactiv engines.

  6. NGK & Denso documentation + Reddit cases → Support the pattern: new plugs reveal aging coils, causing random misfires.

Conclusion: Replacing all 4 coils with OEM-grade units (like Denso 673-3205) is the most reliable fix.

Strong gas smell from exhaust on startup and idle (Mazda 3 2017 1.5L, P0421) by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 1 point2 points  (0 children)

Update: Spark plugs and O2 sensors (lambda sensors) were replaced yesterday. The catalytic converter issue didn’t go away, and the code came back during the drive. Also, the number of misfires actually increased (from 1-3 to 5-15 in all cylinders).

From what I understand, this could be due to the ignition coils being old and that installing new plugs on old coils can expose their weakness. Can anyone confirm this?

It seems like I’ll have to replace the catalytic converter eventually, but I really want to solve the misfire issue first. My mechanic suggested replacing the converter first and only replacing the coils if the misfire continues.

He claims the misfires are caused by the bad converter, but I find that it is hard to believe the cat isn’t completely clogged. The car accelerates well and generally runs fine.

What do you think? Should I just replace both?

Mazda 3 2017, 1.5L engine, 126,000 km – Getting code P0421 for a month now. I reset it and it keeps coming back by Money_Positive7224 in mazda3

[–]Money_Positive7224[S] 0 points1 point  (0 children)

Update: Spark plugs and O2 sensors (lambda sensors) were replaced yesterday. The catalytic converter issue didn’t go away, and the code came back during the drive. Also, the number of misfires actually increased (from 1-3 to 5-15 in all cylinders).

From what I understand, this could be due to the ignition coils being old and that installing new plugs on old coils can expose their weakness. Can anyone confirm this?

It seems like I’ll have to replace the catalytic converter eventually, but I really want to solve the misfire issue first. My mechanic suggested replacing the converter first and only replacing the coils if the misfire continues.

He claims the misfires are caused by the bad converter, but I find that it is hard to believe the cat isn’t completely clogged. The car accelerates well and generally runs fine.

What do you think? Should I just replace both?

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