Q: Does my car have a cold start valve or cold start injector?

Hello There, If your car is E85 equipped, meaning the engine is capable of running on a higher ethanol content fuel (usually indicated by the yellow fuel pumps at the gas station and gas caps), this may cause a lot of the cold start problems you are having as this is a known issue with the 2012-2015 flex fuel Toyota Tundras and Sequoias. What tends to happen with this type of fuel upon cold start situations, the vehicle’s engine control module measures the amount of ethanol in the gasoline and adjusts the air/fuel mixture ratio on the fly depending on this alcohol measurement. 100% gasoline is mixed at a 14.7/1 air/fuel ratio, while E85 (85% ethanol, 15% gasoline) is mixed at a 9.8/1 air/fuel ratio. The ECM adjusts between these two ratios depending on the ethanol content of the fuel (which can range from 0-85% as indicated above).

The problem with this begins with the ECM’s measurement of the alcohol density being incorrect for a cold start. The motor requires even more fuel than normal to get a cold engine started, and using the wrong fuel ratio from the beginning of the process leads to even more skewed startup fuel trims, a hard start and rough running until the engine warms up and stabilizes. If the measured Alcohol Density Estimate is greater than 15% and your fuel trims still read negative/lean, the ECM may need to be reprogrammed to compensate for this adjusting the fuel trim to accommodate additional fuel required for cold starting. I would recommend using a fuel with less ethanol content or taking this to the Toyota dealer to have the ECM reprogrammed to adjust for this.