Do I need a tune to run E85 on an otherwise stock LS?
Yes. Performance Racing Industry's points on E85:
- More fuel: E85 needs about 30–40% more fuel flow to hit the same air-fuel ratio, so the tune must add fuel, and the injectors and pump must keep up (injectors at or below 90% duty cycle, pump with 10–20% headroom).
- Cold starts need their own adjustment; ethanol cold starts can be hard.
- Blend varies: pump "E85" can be as low as 51% ethanol, so a tune for one fixed blend is vulnerable to variation.
- Flex fuel: an ethanol-content sensor lets the computer adapt to whatever blend is in the tank, and also run on gasoline.
See fuel, E85 & boost.
Want to do it yourself? See who tunes it, and how to learn.
Confidence: medium — sources disagree or are limited; check the sources below.
Related questions
- Why would VATS and starter checks refuse to disable on an E38 ECM even after a Write Entire?
- What is the exact procedure to disable DoD/AFM in the tune without a mechanical delete kit?
- How do I set up 6L80E part-throttle and WOT shift tables after a gear and tire change in an engine swap?
- How do I add a real flex fuel sensor to an E38 Camaro and dial in E85 — what needs adjusting beyond enabling multifuel?
- What is needed to segment-swap a 4L60e E38/T42 truck to a 4L80E?
- Does simply selecting 4L80E under the transmission tab convert a 4L60E tune, or is a segment swap required?
Sources
- PRI Education: Converting From Pump Gas to E85 — Performance Racing Industry