Experiencing hard starts and rough idling with your Toyota Tundra, especially a Flex Fuel model? You’re not alone. Many Toyota Tundra owners, particularly those with Flex Fuel vehicles, have encountered a frustrating issue related to the alcohol fuel density reading. This problem can lead to extended cranking times, poor engine performance, and reduced fuel economy. One owner of a 2013 Toyota Tundra Crewmax discovered a surprisingly effective DIY solution using a “Fix It Car Diagnostic Tool”.
The issue stems from an inaccurate alcohol percentage reading in the engine control module (ECM). Even if you’re not using E85 fuel, the sensor might incorrectly register a high alcohol content, sometimes as high as 85%. This misreading causes the engine to run as if it were on E85, leading to a rich fuel mixture, hard starting, stumbling, and that strong smell of unburnt fuel.
Seeking a fix, the Tundra owner referenced Technical Service Bulletin T-SB-0166-19 from Toyota, which addresses this very problem. Hoping for a dealer solution, they were met with a hefty $1200 quote and news of a fuel pump backorder. Furthermore, some owners who opted for the dealer fix reported the problem recurring later on. A quicker and potentially more sustainable solution was needed.
The internet pointed towards resetting the Alcohol Fuel Density level to zero as a temporary, and sometimes longer-term, fix. While some attempted to use a Techstream cable and software, often from unofficial sources, the process was reported to be complex and unreliable. Avoiding the Techstream software headaches and the cost of a Toyota Techstream license, the Tundra owner explored bidirectional scan tools.
After research, the Launch X431 CRP919E emerged as a promising “fix it car diagnostic tool” capable of resetting the alcohol fuel density. Tools like the XTOOL D7 and D8 were considered but confirmed by the manufacturer not to support this specific function on the Tundra. Crucially, the seller of the Launch X431 CRP919E confirmed its capability to perform the necessary reset.
Upon receiving the Launch X431 CRP919E, the owner updated the device to access the latest Toyota-specific functions. Connecting it to their 2013 Tundra, they confirmed the alcohol fuel density was indeed reading an erroneous 85%. Here’s how they used this car diagnostic tool to fix the issue:
- Diagnosis: Navigate to “Diagnose” in the Launch X431 CRP919E menu.
- Toyota System Selection: Choose “Toyota” for vehicle selection.
- ECM-ECT (Engine) Selection: Select the engine control module.
- Special Functions: Access the “Special Functions” menu within the ECM settings.
- Fuel Density Learning Value Reset: Locate and select “Fuel Density Learning Value Reset”. This function specifically resets the alcohol fuel density level to zero.
- Execute Reset: Run the reset function. The process is quick, taking only a few seconds.
The result was immediate and significant. The Toyota Tundra started promptly without hesitation, engine performance smoothed out noticeably, and fuel economy improved. Subsequent checks confirmed the alcohol percentage reading remained at zero.
While the owner acknowledges the possibility of the issue returning, having the Launch X431 CRP919E “fix it car diagnostic tool” provides a quick and easy DIY solution. For a small investment in a versatile scan tool, Tundra owners can potentially avoid costly dealer visits and take control of this common Flex Fuel issue. Beyond this specific problem, a bidirectional scan tool like the Launch X431 CRP919E offers a wide range of diagnostic and maintenance capabilities for various vehicle makes, making it a valuable addition to any DIY mechanic’s garage.
