Diagnosing Lean Air/Fuel Mixture Codes

What Does It Mean?

At CorkSport we are glad to be a source for help with those that have questions about their Mazda. I personally enjoy helping with drivability problems or Check Engine Lights! P2187 is a good example of a common code in the Mazda world. Especially those with Mazdaspeeds. “System too lean at idle.” Now you may be asking, what does this mean, and how is it fixed?

There are other lean codes all of this could apply to; this is a typical example.

It’s quite easy to figure out yourself, and I’ll be walking you through the simple procedure to track down the cause! Using my Mazdaspeed 3, we will go through some of the diagnostic steps of Boost Leak testing, and touch on some other common causes of a lean at idle code.

Let’s get started!

AFR/Fuel Trims

AFR – Measured by your primary 02, your air-fuel ratio is vital to watch and monitor if you are modding or trying to make more power.  Your Mazdaspeed is tuned to hit certain AFR targets, and relies on the 02 sensor and the MAF Sensor (Mass Air Flow) to adjust fuel delivery accordingly. However, there are things that can interfere with how these sensors communicate with the ECU, and if this happens, it will throw your system out of whack.

Examples are vacuum leaks, boost leaks, leaking nozzles/injectors, exhaust leaks, etc.

Fuel Trims – The measurement of how much your ECU needs to adjust fuel delivery. There are two kinds of fuel trims.

Short Term Fuel Trim (STFT) – Cars immediate Reaction To AFR Fluctuations, and responsible for keeping LTFT in check. This is constantly switching around. At Idle you should see close to 0 once it settles. Meaning that the RPMs are not fluctuating, and its steady.

Long Term Fuel Trim (LTFT) – Cars long-term reaction, which will change over time-based off how the short terms are doing. When you get a custom tune, your tuner will do what’s called a MAF calibration, to get this number as close to +/- 0 as possible. The less your ECU has to correct its fuel delivery the better.

Anything (-) means it’s taking away fuel, so the AFR’s its seeing are slightly richer than what it thought they would be.

Anything (+) means its adding fuel, so the AFR’s are slightly leaner than it should be. If you are seeing high or pegged STFT, the ECU is trying it’s very best to correct AFR to target.

How To Fix

Now that you have the basic understanding of what these mean, it will be easier to read the Accessport and see just what is going on. You will be able to watch how the computer is compensating for whatever the problem is, and be able to make a more educated decision on how to track it down.

Assuming the issue isn’t caused by something on the exhaust side, the most popular method would be the boost leak test. Creative name, right?

You can make one of these testers yourself, and it only costs a few bucks. All it consists of is a properly sized (And closed off) PVC section that you clamp onto your intake using a silicone coupler. It looks a little something like this.

Notice that there is a Schrader valve on top (Tire valve) This allows you to pressurize the system with air. You can use a bike pump or an air compressor. Obviously, the air compressor will be a bit easier as you can fill it up much faster.

Pinch off the line running from your intake to your valve cover or oil catch can, you don’t want to be forcing air directly into your crank case.

Attach the coupler to your intake, and start filling it up. Take small intervals to listen for any air escaping. You will want to ensure that the pressure your system holds is above or equal to your boost target.

If you hear air coming from the seal for your Mazaspeed VVT solenoid on your valve cover, this is normal.

Once you start hearing excess air escaping, or your gauge on the air chuck is not showing that it’s holding steady pressure, then you know you have a leak. The best way to visibly spot the leak is by spraying the suspect area with soapy water. It will reveal the leak as shown.

In this case, it was an FMIC coupler. However, these leaks can originate from a bad vacuum line, stuck open BOV, bad gasket. This method will expose any of these things.

What If It’s Not This?

If you have tested your system and found no source of a leak, then the next obvious things would be to inspect your MAF sensor, O2 Sensor, EVAP Solenoid, and exhaust system.

MAF – Sometimes these sensors fail, or get dirty. Cleaning them can sometimes render results but not always. Take it out and inspect it for grim or build up on the wire. MAF cleaner can be purchased at your local parts store.

O2 Sensor – Sometimes O2’s can get sleepy or go bad. Typically, when they do go bad, the readings are a bit more all over the place, or extreme. But it does happen sometimes.

The one responsible for AFR is an expensive Wideband sensor, so unless you’ve tried everything else, don’t throw money at a new one unless you’ve eliminated other variables.

EVAP Solenoid – This is responsible for allowing gas fumes from your EVAP system to be purged into your induction system to be burned off. However, the solenoid can sometimes be stuck open, and allow unmetered air in at the wrong times. Check to see if air passes through, or swap on a friend’s and see if it fixes the problem!

Exhaust – Cracks in the manifold, or downpipe before the 02 can trip up the sensor, thinking there is more air in the mixture than there is. The stream of the exhaust can pull in air from outside and confuse it. Look closely and listen for an exhaust leak. It’s typically easy to distinguish the sound.

Check out our latest CorkSport youtube video to catch a little more detail on this subject!

If all else fails, our staff at CorkSport is here to assist you over the phone the best we can for any of your Mazda or Mazdaspeed needs. Give us a call anytime for quality technical support at 360 260 2675.

Regards,

Brett@CS

Mazda 3 TCR

An interesting article popped up a few days ago in which John Dagy, a journalist with Sportscar365, was discussing the TCR class of cars with John Doonan, the head of Mazda Motorsports program.

I have been following the TCR series for a while now with some interest in it as the car Mazda offers that fits best is the Mazda 3, and I enjoy the time I have had racing CorkSport’s Gen3 Mazda 3.

What is nice about the series is that it is meant to race four-door saloons, all with a 2.0 turbo motor and a price-capped ceiling of 135,000.  Most people would freak out a bit with that price but what you are getting is a fully developed car with a spec sheet.  Each manufacturer designates a builder, whether themselves or a shop, to assemble the cars and provide support.

Mazda is in an interesting spot; they have their successful Global MX5 cup series and the IMSA Prototypes with Joest, but there is a middle-ground hole that has been filled with the older NC Miatas.  With the NCs not being a current production model, it makes sense to get something in there to fill in the blanks.

 In the past, Mazda had used the Mazdaspeed 3 as the basis, and it did well capturing the championships in PWC and IMSA ST class, but the lack of a turbo model makes this a challenge.

One option out there would be to use one of our upcoming 2.5 Skyactiv Mazda 3 turbo kits and bridge the gap so to speak to have a powerplant.  Granted the turbo kit is for the 2.5 but with enough encouragement and feedback from people, the 2.0 kit is looking likely.

Work on some aero and really good suspension, and you would be set.  Maybe I am just daydreaming too much at work again….

-Derrick

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How To Achieve 400 WHP In Your Mazdaspeed

Today I want to share with you a simple blog on just one way of taking your Mazdaspeed to 400WHP. After checking out this blog, If you would like more in-depth information on upgrading your Mazdaspeed with more horsepower then check out 500 WHP post for Mazdaspeed 3.

Let’s Get Started

The MZR DISI engine in the Mazdaspeed platform has been around for just over 10 years now. CorkSport along with the community of racers, shops, and enthusiasts alike have learned quite a bit about these engines. We have learned what they like and what they don’t. How they react to certain mods, how to maintain them, and also some of their weak points. We also learned how to take this platform well over 400 WHP.

We recently hit 684 whp with the CST6 Mazdaspeed Turbo — Check it out here.

Among the many things we have learned, we have developed a great understanding of what is needed to get these engines to make power. More specifically, with the right set of bolt-on parts and tuning one can easily and safely make 400WHP on a stock bottom end of your Mazdaspeed 3 or Mazdaspeed 6. The torque will just need to be kept under control.

It’s not a secret or rocket science on how to achieve this power level in a Mazdaspeed3 or Mazdaspeed6, and it is very much doable.

Stock Red Mazdaspeed3
Stock Mazdaspeed3

Disclaimer:

There are certainly many variables that can come into play when trying to achieve 400WHP safely, such as the health of your engine, quality of engine tune, octane rating of fuel, engine management software and more. This is by no means an all-inclusive guide and the only way of making this level of power. However, this is a tried and tested method of making high power safely and reliably. We come from years of experience doing it ourselves and helping the community with their Mazdas as well. We have spent years and years developing this platform and continue to do so on a daily basis. What I aim to do is educate you on how you can make the most out of your MZR engine.

Necessary Upgrades To Make 400WHP

Now before we get too ahead of ourselves, there are two modifications that are a must before going down the 400whp quest. Those are high-pressure fuel pump internals and a tuning solution such as those provided by COBB or VersaTuner. These parts do not inherently increase hp and tq levels, but they are 100% necessary to give you most out of your hard part modifications and do so with safe and reliable power. A high-quality tune is worth every penny, and when paired with things such as an intake or exhaust, you can capitalize even more so your parts and net more horsepower.

Understanding the DISI MZR 2.3T

The DISI MZR 2.3T is not much different than any other gasoline direct injected engine that you would find on any modern automobile. Here is how it operates:

  • Air goes into your Mazdaspeed.
  • Air is combined with the correct ratio of fuel.
  • The air/fuel mixture gets compressed.
  • A spark event occurs that ignites a controlled burn.
  • This event forces the piston downwards.
  • Exhaust gases then leave the Mazda.
  • The cycle repeats.

So in an oversimplified matter, that is all an internal combustion engine is – a glorified air pump with more bells and whistles. One of the best ways to make a really effective air pump is to optimize the movement of air into and out of the cylinders. For that reason, it’s best to start at the front and back of our car to help give it a little breathing room.

Intake & Exhaust

Mazdaspeed 3 Power Series 3.5" Intake

Mazdaspeed3 Power Series 3.5″ Intake

It’s no secret that an intake and exhaust system are among the most popular first upgrades for any vehicle, and it’s for a good reason. Letting air in and out of the engine as easily as we can is a great first step to create more power. Doing this will free up restrictions with the manufacturer parts, especially on a factory turbocharged vehicle. OEM parts are by and large designed with emissions regulations and pricing priorities, rather than performance.

Upgrading your Mazdaspeed to a 3” or 3.5” intake and pairing it with a turbo-back exhaust will create the airflow efficiency that we need to reach 400 WHP. We’re able to do this by increasing the exhaust pipe diameter and either eliminating our catalytic converter or replacing it with a high-flow race cat. By increasing the efficiency of airflow from entry through the exit, the engine is effectively working less to produce the same amount of power.

By adding an intake and exhaust to your Mazdaspeed, you can net an easy 50+ whp when paired with the proper tune. As you continue down the modification road, you’ll find that this is the most effective dollars spent to horsepower ratio. Now that we are able to take more of the power stroke, we can focus on getting more power to the wheels, rather than letting it be consumed by byproducts such as waste heat, noise, and vibration.

Mazdaspeed3 Exhaust Setup
Mazdaspeed3 Exhaust Setup

Intercooler & Turbo

Another great way to make more power with your Mazdaspeed, and to get closer to 400whp, is to increase the level of boost pressure running through the engine. OEM boost levels are around the 14-15 PSI. But once we have our intake and exhaust installed on our Mazdaspeed, our tuning solution can allow us to start increasing that level into the 19-21 range.

A natural byproduct of increasing the pressure within the system is a corresponding rise in air temperature. To be able to make the most of the increased boost levels, it’s important to keep the temperature at a lower level. To do this, you’ll want to upgrade to a larger top mount intercooler (TMIC), or even go a step further and upgrade to a large front mount intercooler (FMIC) core.

The intercoolers primary function is to act as a heat exchanger, and we know that heat is the #1 roadblock for any engine to make more power. The more efficiently we can remove heat from the system, the more power we can create safely and reliably. We should also note that the stock TMIC in the Mazdaspeed platform is a terrible bottleneck in the system so this will free up extra flow.

Mazdaspeed Front Mount Intercooler
Mazdaspeed Front Mount Intercooler

Now that we have a good way of getting air into, out of, and keeping it cool at the same time, we want to increase the total volume. An easy way to do this is by upgrading the turbocharger in your Mazdaspeed. This is an easy process that replaces your factory K04 Turbo and creates the potential to throw down some serious power. When you reach this point in your build, you open up options on how to proceed:

  1. Make the same power on less boost
  2. Make more power on the same boost
  3. Make way more power on WAY more boost!!!

If we are shooting for 400whp on our Mazdaspeed, then we generally like to choose door #3.

CST4

Side note: We highly suggest / possibly need a 3.5 bar MAP sensor and an electronic boost control solenoid (or EBCS). Once we start to increase our boost pressures north of 21psi, the OEM electronics begin to lose resolution and can negatively affect our tuning if not addressed.

By upgrading our MAP sensor we are allowing the powertrain control module (PCM) to recognize and look up higher boost targets than those equipped from the OEM unit. With this upgrade, the computer can now accurately record and look up these values. We also upgrade our electronic boost control solenoid (EBCS) to allow more fine-tuning of our maps and boost targets. An OEM EBCS just won’t allow us as fine of control of our boost pressure, which can result in some headaches as we approach higher horsepower levels.

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The Finishing Touches To Reach 400 WHP

With the above combination of mods and proper tuning on a healthy engine, a medium frame turbo on pump gas can get you into the 330-340whp range. If we go another step further, we will open up more ‘breathing’ mods such as the intake manifold, taller lift camshafts, or a larger throttle body. This will stretch us into the 350-360 whp range.

That being said without the help of e85 or aux fueling we can’t go any closer to our 400whp mark. We simply hit the limits of the Mazdaspeed factory fuel system and need to look into upgrading that system as well.

Making the switch over to e85 allows us to get in the 380 range, but we soon run out of fuel injector headroom in the Mazdaspeed at this point and max out our injector duty cycle. We then have to look at aux fueling (Meth or Port Injection) as a solution to get us to our 400whp mark safely. What’s unfortunate is that at this point we are also looking at upgrading our hard parts such as our in-tank fuel pump to keep up with demand if you plan to run PI. There are quite a few options for AUX fueling which are beyond the scope of this blog.

Now, as mentioned this is not the only way of making these power levels, but it could be said that it is one of the easiest and most popular. It’s important to remember that along the way we supplement the engine with other supporting mods to ensure we are safe and can make full use of our power. Things like lower heat range spark plugs and a stage 2 rear engine mount can go a long way.

Thanks for following along and feel free to leave us a comment if you have any questions or want some more specific information on a product.

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You May Also Like:

The First and Only Performance Mazdaspeed Throttle Body with NO Sacrifices

Mazdaspeed3 intake manifold and throttle body installed

Many have tried, but few have succeeded to retrofit or modify an existing throttle body to work with the Mazdaspeed DISI MZR platform.

As you know, CorkSport does things a little differently, and as a result, we started from the ground up to create the best performance throttle body possible with no sacrifices to drivability or reliability. Introducing the CorkSport 72mm Throttle Body for 2007-2013 Mazdaspeed 3, 2006-2007 Mazdaspeed 6, and 2007-2012 Mazda CX-7.

Starting from the ground up means 100% brand new parts, no reworked or refurbished components anywhere.  

We start with an aluminum investment cast body that is made to our specific design specifications.

A flat faced throttle plate is added to gain a little bit of extra flow by avoiding the bump of a traditional round pivot shaft.

Finally, new electronics are added that are based upon OE logic to avoid any tuning and calibration issues.

To retain easy installation, we knew we had to keep the OE bolt pattern. With this, we wanted to maximize the throttle plate diameter for maximum flow. We ended up increasing from 60mm to 72mm. This may not sound like a huge increase, but the OE Throttle Body fits inside the CorkSport Throttle Body with plenty of room! The 72mm size also fits well with both 3” and 2.5” intercooler piping to fit almost any TMIC or FMIC setup. Finally, we did away with the OE gasket (which is too small anyway) and replaced it with a durable O-ring that will hold up to oil, gasoline, methanol, and other fueling options that it may come in contact with.


The CorkSport Throttle Body underwent extensive testing to ensure that it will not fail during daily use and to ensure it performs as well as we expect. The throttle plate underwent endurance testing to validate the D-shaped pivot can stand the test of time. During flow bench testing, we found that the CS flows about 150CFM (~33%) better than the OE throttle body when 75% open (accelerator pedal fully depressed).

Check out the graph below for the full data.
Mazdaspeed Throttle Bdy Graph for flowbench testing

In daily driving testing, we noticed better throttle response with no CEL or choppiness. In power testing with a midsized turbo (~GT30 size) we found the throttle body caused faster spool, but when we moved to a big turbo, things got interesting. With a GT35R, the CorkSport Throttle Body caused 100-200RPM faster spooling and an increase in power. Check out the dyno graph down below to see the difference between the CS Throttle body (blue) and the OE throttle body (green).

Dyno stats for the Mazdaspeed 3 Throttle Body

Each throttle body ships with fresh stainless steel mounting hardware, a 3” stainless t-bolt clamp, and your choice of silicone. We have options for FMIC, Mazdaspeed 3 TMIC (which also works for you CX-7 guys), and Mazdaspeed 6 TMIC.

Mazdaspeed Intake Manifold with Throttle Body
If you’re looking to take your Mazdaspeed3, Mazdaspeed6, or CX-7 to the next level, or squeeze that last bit of power out of your big turbo build, the CorkSport Throttle Body can help you meet your goals.

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CorkSport Injector Puller

For the Mazdaspeed 3, Mazdaspeed 6 & CX7

After years of popular requests, we have something that we are very excited to announce! The CorkSport Injector Puller is here, and ready to assist you with your DIY, or shop needs.

With great power, comes great responsibility! And owning a Mazdaspeed may have made you aware by now of how troublesome removing a GDI injector can be. We designed this to assist you.

YOU CAN NOW SAY GOODBYE TO:
  • Twisting a seized injector until it breaks loose
  • Rigging up some method to pull or pry out the injector
  • Beat up hands
  • Beat up injectors
  • Hours of lost time

Now, I know what you are thinking: we may be late to the party. We are aware that we are not the first ones to make such a tool, however, we wanted to ensure that we made one of the highest quality that can be used time and time again. We love that you guys buy our seals, and we wanted to help ease the installation as much as possible.

With its stainless construction, Nator can truly make use of this when it gets passed around, because it won’t deteriorate with use.

As the OE seals fail, carbon starts to built up around the injector and seal and really locks that sucker in there over time. Sometimes an injector has to be sacrificed as seen above. But, It’s amazing how much easier the proper tool can make the job.

Although it may resemble a shake weight a bit, its just your normal slide hammer style tool with a custom head designed to perfeclty fit the DISI Injector.

HOW TO USE:

  1. Take off O-Rings that will be on the tip of the Injector where it goes into the Fuel Rail. Be sure to store those in a safe place.
  2. Slide the head of the tool into position as shown.
  3. You will then put tension on the tool pulling backwards.
  4. Use your other hand to slide the hammer backwards until it hits the lock nut on the back. Repeat until the stubborn injector finally breaks free.

– The CorkSport Team

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