2015 Infiniti Q70 Misfires on All Cylinders: Causes & Fixes
car has misfires on all cylinders
You’ve got a misfire on all cylinders. That’s usually a global issue, not a single coil, plug, or injector. Most likely, something’s messing with air, fuel, or spark across the board. My working hypothesis: either a major air metering problem (like a bad mass air flow sensor), a fuel delivery issue, or a control module problem. If it’s not a simple intake air leak or fuel supply, ECM or wiring is next up.
If you’ve got a scan tool, check for codes and live data. If not, you’re flying blind, but there are still some basics you can check.
Most likely culprits
- Mass air flow (MAF) sensor failure — Throws off air/fuel mix for all cylinders.
- Major intake air leak (post-MAF) — Unmetered air causes global lean misfire.
- Fuel delivery issue (low pressure, dead pump, clogged filter) — Not enough fuel to any cylinder.
- ECM or power/ground issue — Rare, but if everything else checks out, possible.
How to narrow it down
-
Scan for codes and look at freeze frame data.
If you see P0101, P0171/P0174, or all-cylinder misfire codes, note fuel trims and MAF readings. -
Unplug the MAF sensor and start the engine.
If it runs better or differently, the MAF is likely bad. -
Spray carb cleaner or brake clean around intake manifold and vacuum hoses while idling.
If RPM jumps, you’ve got a vacuum leak. -
Check fuel pressure at the rail (spec: 51 psi at idle for most VQ engines).
If it’s low, suspect pump or filter. -
Verify battery voltage and main engine grounds.
Low voltage or bad grounds can cause global misfire. -
If all above checks out, inspect ECM connectors for corrosion or water intrusion.
If you see green crust or moisture, that’s a problem.
Possible parts (if needed)
- Mass air flow sensor
- Engine control module (ECM)
A few questions
- Any codes besides misfire? List them all, including pending/history.
- Did this start suddenly or after any recent work (battery, air filter, etc.)?
- Does the engine start and run at all, or is it a no-start/rough idle only?
Let me know what you find on those checks. That’ll point us right at the root cause.