Integrated Engineering’s TrueFlex™: A Smarter Way to Run Ethanol Blends
One of the biggest advancements in engine tuning over the last decade has been flex fuel technology. Flex fuel tuning allows the engine to automatically adjust to different blends of gasoline and ethanol. Integrated Engineering’s TrueFlex™ system introduces this to aftermarket tuning by using real-time ethanol data and custom ECU code to give drivers more power, safety, and convenience. On the contrary, most competitors offer individual tunes designed for a specific ethanol blend (for example, E40), which requires reprogramming the ECU, and is not user-friendly.
Whether you’re new to ethanol tuning or already familiar with ECU and TCU calibration, this guide breaks down how TrueFlex works and why it matters for performance-minded drivers. Let’s dig in.
What is TrueFlex? Real Flex Fuel, Not Guesswork
IE calls it TrueFlex because it uses real ethanol content data taken directly from a flex-fuel sensor. The ECU reads this data, stores it, and IE’s custom software accesses it to adjust maps in real time. TrueFlex creates tuning tables that weren’t originally in the ECU at all. To name just a few, these custom tables adjust crucial variables such as fueling requests (often referred to as Set Point Value versus Actual Value), Ignition timing, and boost/load requests.
Monitoring and adjusting these variables in real time allows the car to safely and efficiently run any blend—from straight pump gas (E0) up to E100, typically without the need for flashing a new tune.
Why Ethanol Makes More Power
Higher Knock Resistance = More Ignition Advance
Ethanol’s biggest performance advantage is its resistance to knock (pre-ignition). With ethanol, the tuner can safely advance ignition timing more than gasoline allows. Increasing timing, when safe, allows more torque and horsepower. In a nutshell, since ethanol burns cooler than gasoline in the combustion chamber, timing can be increased more than with gasoline.
What Is Pre-Ignition? (And Why Ethanol Helps Prevent It)
Pre-ignition occurs when parts of the air-fuel mixture ignite before the spark plug fires at the intended moment. This sends pressure spikes through the cylinder while the piston is still travelling upward. You have most likely heard this referred to as knock, pinging, or detonation.
The ECU’s knock sensors detect this and reduce timing to protect the engine, reducing power. Since ethanol naturally resists knock, the engine can run more ignition advance without triggering these safety corrections.
Plug-And-Play Installation
TrueFlex is designed to be a simple installation, as long as you have basic wiring skills. If you have never done any wiring projects before, we recommend grabbing a friend with more experience or having an approved IE installer do the work for you. Our plug-and-play components include:
- Wiring Harness
- Ethanol Content Sensor
- Factory Style Connects
- All Required Mounting Hardware
- PowerLink Tuning Cable and Matching ECU Tune
After installing the kit, you simply flash the TrueFlex ECU tune. From here on out, you will never need to manually switch between different software files when changing ethanol percentages. For those who have ran ethanol files the “old school” way, you understand how awesome this is, and how much time it saves.
Safety: Why TrueFlex Protects Your Engine Better
Running a fixed ethanol tune (like an E40 or E85 file) on unpredictable pump ethanol can be risky. If you use a manual ethanol test kit and test the blend from different gas stations, you will most likely see inconsistent results. Without an ethanol sensor that adjusts in real time:
- You may run too lean with higher ethanol than expected
- You may run unsafe ignition timing with lower than expected ethanol
- You may exceed fuel system capacity with higher than expected ethanol
Frequently Asked Questions (FAQ)
1) What happens if an ethanol sensor fails?
Firstly, it is important to note that common engine sensors are wear components and typically do not last forever. If an ethanol sensor fails and you’re using TrueFlex Software, IE’s built-in diagnostic safety mode is activated. Timing and fueling maps will be adjusted immediately to prevent catastrophic engine damage.
Additionally, many IE tunes also include the proprietary Auto Protect, which prevents ignition correction from reaching levels that could cause damage during unexpected knock events. Learn more about this feature by reading this blog article about Auto Protect.
2) What happens if you run the wrong ethanol blend?
Here are two different examples that demonstrate what happens if you run too much or too little ethanol while using software that does not automatically adjust variances. Either of the examples below may cause engine damage.
For example, if your car is tuned for E40 and you accidentally use E85:
- The ECU will run too lean
- Fuel trims will spike
- You may run out of fuel system headroom
Another example. If your car is tuned for E40 and accidentally uses E20:
- Too much fuel is injected
- Ignition timing becomes unsafe
- Knock correction increases sharply
3) What hardware is required to run TrueFlex?
IE offers TrueFlex for many different vehicles. Be sure to check the requirements for your specific car, but as a general rule of thumb, the following parts are required or recommended:
- IE TrueFlex Kit
- Upgraded High Pressure Fuel Pump (HPFP)
- Upgraded intercooler
- High-flow intake system
- Optional turbo inlet or charge piping
- Optional Catback Exhaust
4) Is there anything I should do before upgrading to TrueFlex or performance software in general?
We often refer to this as "stage 0." The following components should be checked and in most cases, replaced for peace of mind:
- Fresh spark plugs
- A fresh set of ignition coils
- Check for vacuum or boost leaks
- Scan for codes. Using a diagnostic cable such as OBD11 or the IE PowerLink, scan your car for fault codes. Keep in mind, there can be “soft codes.” These are codes that do not trigger a check engine light, but still may be present. If codes are present, before proceeding, reach out to our support team to ensure the tune will operate correctly.
5) Do I need to switch tunes when changing ethanol mixtures?
No, TrueFlex allows any mixture from E0 to E100 without flashing between different software files?
6) Is ethanol hard on fueling components?
Modern systems are designed for ethanol. Running pump gas occasionally helps maintain detergents. We recommend not storing your car for extended periods of time with high ethanol percentages.
7) How does cold weather affect driveability when using high ethanol mixtures?
Ethanol struggles to vaporize below about 40°F. TrueFlex adjusts cold-start fueling based on actual ethanol content. In extremely cold conditions, below 0 degrees, running a lower percentage of ethanol may be helpful.
8) How is fuel economy affected?
Fuel economy decreases as ethanol content rises, but you can switch back to pump gas anytime for commuting or long road trips.
9) Does TrueFlex ethanol tuning require an aftermarket high-flow downpipe?
No, all IE TrueFlex tunes are engineered for the stock/factory catalyst.
10) What cars do you offer TrueFlex technology for?
We offer TrueFlex for several Volkswagen and Audi vehicles. Check the specific product page for your car for more information. We also offer flex fuel tuning for Ford under our Xodus tuning brand.
Still have more questions? Reach out to our helpful support team.