Vehicle: 2012 Toyota Sequoia, 4WD, V8-5.7L (3UR-FBE), Flex Fuel, Automatic Transmission/Transaxle

Mileage: 189,488 miles

Problem: This Sequoia was brought in because of an exceptionally long cranking time only on cold starts. Once started, the engine ran well with no misfires. The malfunction indicator light (MIL) was on.

Case Details: When the technician connected a scan tool, he noticed that the fuel alcohol content showed 85% on the data stream. Long-term fuel trim was at negative 27%. He doubted this was a fuel pressure problem, but he checked anyway. It was at specifications. The short-term trim on both banks were right around zero, and he found the following two diagnostic trouble codes (DTCs):

• P1604 – Startability Malfunction
• P1605 – Engine Speed Dropped Below Set Speed

The technician really couldn’t find any glaring problems, so he called an ALLDATA Tech-Assist consultant for some ideas of what to check next and to find out why the alcohol content reading increased that much.

The consultant said that if the alcohol content in the fuel showed 85% on the scan tool, this could cause the hard starting issue, assuming the customer is using regular gas. Otherwise, the fuel trims would be positive. He advised resetting the alcohol content reading using a scan tool under the “Service Functions” section.

The consultant went on to explain that the reason the fuel alcohol content reading increased was that, in the U.S., we use up to 10% ethanol to meet air quality standards and the minimum 87 octane fuel requirements. Over time, the alcohol content values compound in the PCM, and a scan tool is required to reset them.

Confirmed Repair: The technician verified that the customer was using only regular fuel then performed the alcohol content reset with his scan tool, cleared the DTCs, and cleared the fuel trim values. The engine started normally when it was cold. He took the vehicle on multiple drive cycles to get all the monitors to complete. The fuel trims stabilized right around 0%, and the alcohol content reading stayed at 0%. Weird problem solved!