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Tuning Facts and FAQs

RR Racing has pioneered Lexus ECU tuning.  We were the first to release a tune for Lexus ISF in 2015, then the first to tune the RCF and GSF, we then developed the tune for Lexus IS350 2006 to 2013 and finally IS350 2014 through 2017.  Last year we introduced the best tune for Lexus IS250 available anywhere.  So needless to say, we know a thing or two about Lexus tuning.    We would like to clear some misconceptions customers have regarding tuning a Lexus, as well as answer some FAQs.  Some of these are based on experience they may had with older cars, and many of these are based on erroneous information they get from other tuners.

What is tune and what are its benefits?    RR Racing has a detailed feature description for each of our tunes.  Generally, we modify maps (or data tables) in the stock ECU in order to allow it to switch to more aggressive operating parameters.  Most of our tunes enhance the following:

  • Direct Injection / Port Injection fuel mapping
  • Ignition control (ISF has base ignition maps, cam timing dependent ignition maps, knock correction maps)
  • Intake and Exhaust variable cam maps
  • Torque to throttle mapping (allows us to enhance throttle response)
  • Optional rev limit increases to 7200
  • Raise the speed limiter to the maximum allowed by the ECU

Dyno tuning.  Many customers believe that custom Dyno tuning is the best way to tune a car.  In some cases this is the case, but due to the nature of adaption modes in the Lexus ECU, most tuning should be done on the street, with only final adjustment and confirmation of power gains performed on the dyno. 

One of the reasons that dyno-only tunes are not effective has to do with Lexus ECU adaption and learning capability.  There are many aspects of the tune, such as ignition timing and fueling, that strongly depend on obtaining a high and stable knock correction learning value (KCLV).   It is only through tuning on the street or track, I practical real life conditions that one can evaluate the long term KCLV learning behavior under different states of tune. Please refer to the article below titled “Improving ECU Learning and Power on Lexus ECUs” for more detailed information about KCLV.

So if your tuner says they can “custom tune” your Lexus on the do, you should question how much real world Lexus tuning expertise they actually have!

This is why we take a long time to develop a new tune – a new tune may be developed over an extensive period of testing, under varying real-world driving conditions.  Only after we feel that the tune works well on the road, we test it on the Dyno to confirm the results.

Please refer to the tuning instructions we ship with our tunes and Tuned Intakes for how to properly test your Lexus on a Dyno. 

Do you need a new tune after installing new equipment?  Many customers ask whether they need to get a new tune after they install exhaust, headers or intake.  As we already mentioned, most commercial intakes for Lexus cannot be tuned (with exception of RR Racing Tuned Intakes).  Some tuners promote the idea that customers need a new tune when adding new equipment in order to sell more tunes.  While this is true for some model vehicles equipped with MAP load sensor, Lexus vehicles measure load with an extremely accurate mass airflow sensor (MAF).  So when we develop our tunes on cars with highest modifications available, our tune is optimize for both full bolt on as well as totally stock vehicle. The ECU will adjust automatically when this equipment is installed.  So even if you flash our tune when your car does not have an exhaust or headers, you will not need a new tune – your ECU is pre-calibrated to adjust to changes in airflow resulting from once this equipment is installed.

Tunes that make backfire “gurgle”, or “popcorn” sounds.  Some customers ask for tunes that make loud backfire sounds. These sounds happen when ECU ignites a rich air/fuel mixture when the exhaust valves are open.  We do not program such tunes as this can be detrimental to the long term service life of the engine.

What is ECU Learning?  Please refer to the tuning instructions we enclosed with our tuning product for your specific model ECU learning process.  ECU learning is mainly how Lexus ECU adjusts KCLVs (knock correction learning value) based on sensory inputs over time.  Lexus has very sensitive knock sensors.  KCLVS will determine the maps ECU select.  After the ECU was re-programmed/tuned, KCLVs are at the most conservative default values.   Based on sensory inputs, ECU adjusts the KCLVs over time (typically about 50 miles of driving).  When the intake temperatures are too high or there are other engine malfunctions such as bad spark plugs, bad injectors, or any engine condition that could cause a loss of compression or “false knock” etc., ECU will not set KCLV at optimum and will not switch to the most aggressive maps to preserve the engine. 

Can you always expect for a tuned ECU to make more power?  RR Racing invests considerable effort in developing our tunes.  Our tunes are the most tested tunes on the market, and we stand behind the results we post for every tune.  Given the reputation of our tune, some customers believe that a tune will improve their car’s power under any circumstances.  We do not and cannot change the way Lexus ECU works.  As indicated above, Lexus ECU is designed to control the engine optimally based on condition of the engine and the environment.  In other words, if the fuel is bad (low octane 91 or even lower), the temperature is too hot, or some engine components do not work optimally, the ECU will try to save the engine and will now switch to the most optimal maps that make the most power.  So, if you feel you are not getting the power you expect, first of look if your car is running well and consider the weather conditions and fuel quality, as well as engine related issues.  Generally speaking, we find that a simple compression test is the best indicator of the “tenability” and overall health of the engine.

If more smoke comes out of my exhaust, does my car run too rich? There are many reasons why excessive smoke comes out of the exhaust. If you install headers, for example, the car will smoke more and smell more. Another common reason is when engine oil was over-filled during oil change. Mechanics typically fill to the highest level on the oil deep stick. Many believe that more oil is good. Deep sticks maybe slightly modified when installing headers making them less accurate. We suggest filling oil based on specified oil quantities in your car’s owner’s manual — do not fill more. If you installed our Air/Oil separator, make sure to empty the canister. A full canister can cause excess oil to be flown into the engine causing excessive smoke.