PEY6, PEY7 Engine

Mazda 2.0 SKYACTIV-G (PEY6, PEY7) – Experiences, issues, fuel consumption and used car buying guide

Key points (TL;DR)

• Exceptional reliability: Thanks to the absence of a turbocharger and a simpler design compared to modern downsized engines, the PEY6/PEY7 is considered one of the most durable engines in its class.
• Timing chain drive: There is no timing belt; instead, it uses a long-lasting chain, which reduces maintenance costs.
• Direct injection and carbon build-up: The biggest weakness is carbon build-up on the intake valves, which requires cleaning roughly every 100,000 km.
• Dual-mass flywheel on a petrol engine: Manual transmission versions have it, which increases clutch replacement costs.
• Naturally aspirated character: The engine likes high revs; at low revs in a heavy body it can feel sluggish.
• LPG (Autogas): Installation is very unprofitable and complicated due to the direct injection system.

Contents

• Introduction: Revolution instead of evolution
• Technical specifications
• Reliability and maintenance
• Specific parts and costs
• Fuel consumption and performance
• Additional options and modifications
• Gearbox and power delivery
• Buying used and conclusion

Introduction: Revolution instead of evolution

When the automotive industry massively moved towards downsizing and adding turbochargers, Mazda decided to go against the grain. They introduced the SKYACTIV-G technology. Engines with the codes PEY6 and PEY7 are 2.0-litre naturally aspirated petrol units with an extremely high compression ratio (14:1, similar to diesel engines). These engines have proven to be an excellent choice and are most commonly found under the bonnet of the popular SUV Mazda CX-5 (including the 2015 facelift).

Technical specifications

Reliability and maintenance

The Japanese did a fantastic job here. The PEY6 and PEY7 do not use a timing belt but a timing chain. The chain design is quite robust and long-lasting, so there is no classic “major service” at a fixed mileage. The condition of the chain is checked visually and acoustically, and it is replaced only if it starts rattling on a cold start (which happens rarely, usually well beyond 250,000 km, provided the oil has been changed regularly).

Oil consumption and regular servicing

The sump holds about 4.2 litres of oil. Mazda insists on a thin 0W-20 oil grade to achieve good fuel economy and proper lubrication of the VVT (variable valve timing), although 5W-30 is allowed in warmer climates. As for oil consumption, the engine is very well sealed. Minimal consumption between services (up to 0.5 litres per 10,000 km) is normal, especially if the engine is often revved high.

Most common issues and spark plugs

As with most direct injection engines, the Achilles’ heel of this engine is carbon build-up on the intake valves. Fuel is injected directly into the cylinder, not over the valves, so there is no liquid to “wash” them. Symptoms are rough idle (misfires), a slight loss of power and increased fuel consumption. The solution is mechanical valve cleaning (often done by walnut shell blasting) every 80,000 to 100,000 km.

The air-fuel mixture is ignited by special iridium spark plugs adapted to the high compression ratio. Their service life is impressive – they are replaced at 100,000 to 120,000 km, but due to their specific design they are quite expensive (depends on the market).

Specific parts and costs

Although it is a petrol engine, the technology behind it is similar to that of modern diesels. This is where there is a catch for buyers of manual models: this engine uses a dual-mass flywheel. Replacement of the dual-mass flywheel together with the clutch kit is a job that usually awaits you between 150,000 and 200,000 km, and it is expensive (depends on the market).

The injection system operates at extremely high pressure. The injectors are robust but sensitive to fuel contamination. If an injector fails, symptoms include black smoke (rich mixture), rough running and the “Check Engine” light coming on. New OEM injectors are very expensive (depends on the market), so it is advisable to refuel only at reputable stations.

Fortunately for owners, since this is a naturally aspirated petrol engine, there is no turbocharger (neither one nor two), and likewise no DPF filter and no AdBlue system. There is an EGR valve, and it can get clogged with soot, but it is relatively easy and cheap to clean and rarely requires complete replacement.

Fuel consumption and performance

The Mazda CX-5 is not a light car (it weighs over 1.4 tonnes). With 210 Nm of torque available only at higher revs (around 4000 rpm), the engine can feel a bit “lazy” in city driving and when setting off. For brisk overtakes on country roads, you must always drop one or two gears – this engine likes to rev, and only then does it show its full 165 hp.

Real-world fuel consumption:

• City: Expect between 8.5 and 10.5 l/100 km, depending on traffic and driving style. For a 2.0-litre SUV, this is an excellent result.
• Open road: On secondary roads, consumption drops to about 6–6.5 l/100 km.
• Motorway: At 130 km/h, the engine spins at a comfortable ~2800 rpm (with the six-speed manual), and consumption is around 7.5 to 8 l/100 km. The aerodynamics of the high ground clearance take their toll here.

Additional options and modifications

LPG installation

Should you install LPG on a SKYACTIV-G? Short answer: It is not recommended and is hard to make cost-effective. Due to direct injection, standard sequential systems do not work well. A specialised direct injection LPG system must be installed, which is very expensive (depends on the market). In addition, even on LPG the engine must use a certain percentage of petrol (around 15–20%) to cool the petrol injectors in the cylinder. To make the investment pay off, you would need to cover really huge mileages.

Remapping (Stage 1)

If you think you can wake this engine up with a remap, save your money. Naturally aspirated engines do not have a turbocharger whose boost can be increased. A “Stage 1” remap will gain you at most 5 to 10 hp, which is absolutely imperceptible in a heavy SUV. Any money invested in Stage 1 on a PEY6/PEY7 is money thrown away.

Gearbox and power delivery

With this engine Mazda paired its in-house creations: the six-speed manual SKYACTIV-MT and the six-speed automatic SKYACTIV-Drive.

The manual gearbox is a mechanical masterpiece – precise, with short throws (similar to the Mazda MX-5). The most common problem is not the gearbox itself, but the aforementioned dual-mass flywheel and clutch disc. It is recommended to change the oil in the manual gearbox every 60,000 to 80,000 km.

The automatic gearbox is a classic torque-converter automatic. It does not use problematic dual-clutch technology (DSG). It is extremely reliable, shifts smoothly (although it is not the fastest on the market) and matches the character of the naturally aspirated engine very well. It does not have a dual-mass clutch flywheel like the manual. The biggest mistake owners make is believing in “lifetime oil”. The oil in the automatic gearbox must be changed (ideally by machine flushing) every 60,000 to 80,000 km to keep the valve body (mechatronics) healthy.

Buying used and conclusion

What to check when buying?

1. Cold start: Listen to the engine for the first 5–10 seconds on a cold morning start. Any strong metallic rattling indicates a stretched chain or problems with the VVT mechanism, which is a sign of neglected maintenance.
2. Idle behaviour: If the warmed-up engine slightly shudders and the revs fluctuate, this usually means the intake valves are clogged with carbon. Diagnostics will often show “random misfires” codes.
3. Clutch test (for manuals): Start uphill from a standstill with light throttle. Vibrations in the clutch pedal and knocking indicate that the dual-mass flywheel is nearing the end of its life.

Conclusion: Who is this engine for?

The PEY6 / PEY7 engine (2.0 SKYACTIV-G 165 hp) is an excellent choice for drivers who value mechanical reliability above all. The lack of a turbo means one big (and expensive) problem less, but in return it requires getting used to an old-school driving style – downshifting and flooring the throttle when overtaking. It is great for family use, maintenance is not excessively expensive, but when buying you should definitely budget for a thorough intake manifold and valve cleaning. If you have a choice, the automatic version offers significantly more comfort in city driving and saves you the cost of replacing a dual-mass flywheel.