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Thread: Any ideas when 3.5 ecoboost stays in open loop/ cold start fuel source on warm start?

  1. #1

    Any ideas when 3.5 ecoboost stays in open loop/ cold start fuel source on warm start?

    I recently changed my truck over to E-85 (2020 3.5 ecoboost). All my wide bands and everything work as they should whenever I start the truck when it is cold and it warms up. If it sits for a little while and I restart it? I can drive it over an hour, and it still registers an open loop and the fuel source says ?start-up/cold engine?. Anyone have any ideas on reasoning? Idle is smooth and temp is reading up to temperature.
    Last edited by Perna00; 05-28-2023 at 07:06 PM.

  2. #2
    I check some additional pid’s and the engine is definitely up to temp (ran about 120 F) and it still stayed in cold engine/startup for “fuel source”. Engine O2’s are not reporting and trims or lambda readings and engine is reading “no” for closed loop so something is making it think it isn’t warmed up for fuel source. Torque and timing are reading like normal without any temperature modifiers. I look though the editor and can’t find anything relating to open/closed loop settings. It’s almost like the O2 sensors aren’t reading as warmed up but I can’t find a pid to verify and there are no codes in memory. Does this info help towards a solution…?
    Last edited by Perna00; 05-28-2023 at 08:14 PM.

  3. #3
    So I started the truck from a cold start this morning and it still would not go into closed loop mode. I verified temperatures/settings and nothing was prohibiting it. I ended up rewriting the same tune again and it it started working again. It must’ve been some sort of error on the initial write.