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EFI Tuning Fundamentals

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Discussion and questions related to the course EFI Tuning Fundamentals

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I'm wondering what might be the problem with my 2004 Ford Mustang SVT Cobra (aka Terminator). When i am close to WOT but not fully, the car will build 15 psi of boost and run fine. But if i fully mat my foot down on the floor, it drops down to 5 psi of boost and bogs hard. Could this be the result of incorrectly tuned fuel tables? I haven't verified but previous owner said that is is on stock injectors and pump. The car's mods are Steigmeier stage 4 ported blower, 2.8 upper pulley, 6 lb lower pulley, metco idlers, CAI, and full exhaust. The A/F ratio cruising hovers around 13.5-15.0 and WOT is 10.5-11.2. That's about all the information i can think of off the top of my head.

A little background info it could help us.

Was the car running fine and then you started to experience the issue?

Is the car properly tuned?

If you slowly (gradually) put the pedal down to 100% do you experience the issue? Or it’s only when you slam it quickly to the floor? The later could indicate accel enrichment tuning issues.

What does the EFR/lambda show when the engine bogs down? If it was an AFT issue I'd expect to see it there but if you're 10.5- 11.2 is correct, that would suggest both the fuelling is about right, and there's probably no misfire which would be expected to show a lean condition.

Does this happen at all rpm levels, or can you apply full throttle at lower rpm and have it develop?

What fuel are you using, and what is recommended for the conversion - it sounds rather like the management is pulling timing because of detonation and/or pre-ignition. Can you check the data logs for that?

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