Mitsubishi 4J1 Tuning

"All you need to know about tuning the Mitsubishi 4J1 engine!"

Here we review and look at 4J1 tuning and report on the premier modifications for your car. Mitsubishi 4J1 provide a fun base for your project and with the optimum performance parts like remaps, turbo improvements and camshafts you will really maximise your driving experience.

History, Power & Specs of the 4J1 Engine

Inline 4-cylinder SOHC 16v, MIVEC

4J10

102 kW (139 PS) at 6000 rpm 172 Nm (127 lbft) at 4200 rpm

  • 2013 Mitsubishi RVR (Japan)
  • 2017 Mitsubishi Grand Lancer (Taiwan)

4J11

110 kW (150 PS) at 6000 rpm 195 Nm (144 lbft) at 4100-4200 rpm

  • 2013-2016 Mitsubishi Outlander
  • 2020- Mitsubishi ASX

4J12

124 kW (169 PS) at 6000 rpm 220 Nm (162 lbft) at 4200 rpm

  • 2016 Mitsubishi Outlander (Only vehicles for South Africa and Argentina)

2016 - present Mitsubishi Outlander (ES, SE, SEL Trims in United States and Puerto Rico)

2013 - 2017 Mitsubishi Outlander (Australia)

 

Tuning the Mitsubishi 4J1 and best 4J1 performance parts.

Best 4J1 upgrades

Just because particular upgrades are are common on 4J1 it doesn't mean you should fit it, instead we'll best upgrades that will give your 4J1 the best power gain for you money.

Altering your 4J1 cam will make a dramatic difference to the engine engines power. Choosing a higher performance cam profile raises the engines power accordingly.

Fast road cams normally increase the power over the rev range, you may sacrifice a little low down bhp but top end will improve.

Competition cams, increase the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a car used daily you need to match your torque band to your driving style.

I'd never find a 4J1 Motorsport and race cam is a pleasure to live with when on the daily commute, because the lumpy idle will make the car prone to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

Different 4J1 engines respond better to mild camshaft durations so view each engine as unique.

The ECU mapping and fuelling also have a large bearing on the power gains you'll hit.

Altering valve durations can alter the power band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

Typical stage 1 mods often include: Panel air filters, Sports exhaust manifold, Fast road camshaft, Intake headers, drilled & smoothed airbox, Remaps/piggy back ECU.

Typical stage 2 mods often include: fuel pump upgrades, high flow fuel injectors, Fast road cam, Ported and polished head, induction kit, Sports catalyst & performance exhaust.

Typical stage 3 mods often include: Internal engine upgrades (head flowing porting/bigger valves), Competition cam, Crank and Piston upgrades to alter compression, Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions.

The 4J1 power plant respond well to mods and thankfully there are plenty of mods and tuning parts around.

ECU mapping allows a tuner to release the full potential of all the parts you've done to your 4J1.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome usually rely on the parts you've applied and the condition of your engine.

It is the whole point to any engine modification project to force more air and fuel into the 4J1 engine

Air Intake manifolds transmit the air from the air filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

The shape and flow rate of the Intake headers can make a noticeable difference to to fuel atomisation and engine efficiency on the 4J1.

On popular production engines air intake manifolds are crying out for aftermarket parts, although a few car makers provide fairly well optimized air intake manifolds.

Increasing the 4J1 valve size, carrying out port matching and head flowing will also lift performance, & more importantly will make space for raising the performance increase on other tuning mods.

4J1 Turbo upgrades

NASP engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your 4J1

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes major power gains.

When your motor has a turbo already fitted upgrades are relatively easy and we find turbo engines are made using strengthened components.

However engines have weakspots.It is important to find these limitations and install better quality components to survive the power.

We've seen car owners spending a lot of money on turbo upgrades on the 4J1 only to suffer the humiliation of seeing the engine explode soon after it's been completed.

Large upgraded turbo units tend to experience low end lag, and little turbo units spool up much more quickly but won't have the high rpm bhp gains.

Over the last 20 years the choice of turbo units is always increasing and we now see variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end power.

Twin scroll turbo units divert the exhaust flow into 2 channels and flow these at differently profiled vanes in the turbo. They also improve the scavenging effect of the engine.

You'll commonly see there's a restriction in the air flow sensor MAP/MAF/AFM on the 4J1 when loads more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited performance at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although more difficult to configure. We have this feature on twinchargers if you want to read more.

Fuelling

Don't forget to improve the fuelling when you are increasing the performance - it makes the car more thirsty. It makes sense to over specify your flow rate on the injectors.

The rule of thumb is to add 20% to the flow rate when specifying an injector, which takes into account injector deterioration and allows some spare capacity should the engine require more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

4 Cylinder turbocharged engines

  • 58 PSI 340cc/min 200hp
  • 58 PSI 511cc/min 300hp

4 Cylinder NASP engines

  • 58 PSI 285cc/min 200hp
  • 58 PSI 426cc/min 300hp

4 Cylinder supercharged engines

  • 58 PSI 312cc/min 200hp
  • 58 PSI 468cc/min 300hp

4J1 Performance Exhausts

You should look to increase your exhaust if the existing exhaust is actually causing a flow problem.

On most factory exhausts you should find that your flow rate is still fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts can usually air flow out of the engine but do not go too wide or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to 2.5 inches for best results.

Typically exhaust restrictions can be traced to the filters installed, so adding a freer flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

Weak spots, Issues & problem areas on the 4J1

The 4J1 engines are generally reliable and solid as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the 4J1, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your 4J1 engine please join us in our friendly forum where you can discuss 4J1 tuning options in more detail with our 4J1 owners. It would also be worth reading our unbiased Mitsubishi tuning articles to get insights into each modification and how effective they will be for your car.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which modifications work best for them on each model of car. Comments are used to improve the accuracy of these 4J1 articles which are continually updated.

PLEASE HELP: I NEED YOUR DONATIONS TO COVER THE COSTS OF RUNNING THIS SITE AND KEEP IT RUNNING. I do not charge you to access this website and it saves most TorqueCars readers $100's each year - but we are NON PROFIT and not even covering our costs. To keep us running PLEASE Donate here

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Feedback

Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article




Member Benefits

Join our forum today and benefit from over 300,000 posts on tuning styling and friendly car banter.

You will also have full access to the modifed car gallery, project car updates and exclusive member only areas.

(All car owners of all ages and from all countries are welcome).


Popular articles

Diesel tuning
ECU remapping
double clutching
Safety mods
Induction Kits
Customize a car
Performance Chips
Modified car insurance
Track day insurance
Diesel remaps
Calculate MPG
DPF unblocking tips


Boost Controllers

Boost controllers and remaps
Read more...

Stroker Engines

Stroker engines
Read more...

Alloy Wheels 2

Alloy wheels – choosing the best rims.
Read more...

Car Stickers

Car stickers – vinyl printed stickers.
Read more...

Garages

Choosing and caring for garages
Read more...

Best Car P2

Our look at the best coupe, classic, automatic, and Diesel cars
Read more...

MPG Calculator

MPG calculator UK miles per Gallon – calculate MPG
Read more...