2018 GT S550 Intermittent Stalling - Ford Mustang Forum
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post #1 of 4 (permalink) Old 3 Weeks Ago Thread Starter
robvanvoorhis's Avatar
Joined: Nov 2019
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2018 GT S550 Intermittent Stalling

Hello Folks

My 2018 GT S550 has a Roush Phase 1 Kit. After 1 year of perfect enjoyable driving, out of the blue the engine began to intermittently stall, usually when rolling up to a stop light or sign. I have the 10sp auto, has anyone experienced anything like this? Roush, after having an open repair ticket with them for 130 days has decided my long tubes are to blame??? They reflashed their tune, changed the throttle body and a few other very minor things to no avail. They say the solution is to go back to factory exhaust or do a custom tune, any thoughts?

Thanks - Rob

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post #2 of 4 (permalink) Old 3 Weeks Ago
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Are the LT headers all you've done to the car? In most, if not all cases, adding mods that change the Air/Fuel mixture, i.e. headers, you'll need a new tune. The tune Roush installed is a very conservative tune (EPA standards) and is based on what they do to the car, not what the owner may do...later. My guess is, you need a new tune, running a bit tooooo lean. If you decide to get a new tune, seek out a speed shop that is well known for dyno tunes, the only way to get a perfect tune just for your car.

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post #3 of 4 (permalink) Old 3 Weeks Ago
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did the problem start right after installing the LT headers? if yes, that's a sign . . .

and yeah I would assume it needs a custom tune for the headers, since they change the location of the O2 sensors which affects the signal going back to the computer

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post #4 of 4 (permalink) Old 3 Weeks Ago Thread Starter
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Thank you!
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