Tune Guidance

[SazMayo]

Just got headers. Time for a tune. Not sure what route to take honestly. My local shop (The Shop CT) suggests Palm Beach. Another tuner in Connecticut (Turbo Mike) has done custom tunes for a bunch of Mustangs. Curious what others have used, custom tune or piggyback, what works, what doesn't etc. Any feedback honestly is appreciated for a first timer. I don't mind spending the money on a nice tuner for easy flashing and monitoring etc. Again, any help is much appreciated.

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[K4fxd]

The big box tuners are hit and miss. They mostly don't like trouble shooting when things don't work correctly.

Ask your local tuner for a few references.

 

[Cobra Jet]

Can someone explain why the S550 needs to be tuned with just a simple header swap?? Is this tuner snake oil about needing a tune just for headers???

I recall seeing another thread regarding LT header swaps and some M6G members were saying a tune is not a requirement.

I myself am not seeing any reason why on a S550 the change from stock headers to aftermarket shorties or even LT's would require any type of "tune". We're talking about exhaust gases exiting the heads into headers with now improved flow through the remainder of the exhaust system. I mean O2's are still downstream of any header changes, no?

 

[K4fxd]

Some think it is needed because the rear O2 sensors are no longer contributing to the fueling. Tuners cannot turn them off so on some cars a tweak to the fueling tables might be needed. There might also be a problem with the transport delay. This is the time from when the cylinder fires and the computer expects a signal from the O2 sensor.

Personally I wouldn't worry about it, the car will compensate for the small changes.

 

[SazMayo]

Some think it is needed because the rear O2 sensors are no longer contributing to the fueling. Tuners cannot turn them off so on some cars a tweak to the fueling tables might be needed. There might also be a problem with the transport delay. This is the time from when the cylinder fires and the computer expects a signal from the O2 sensor.

Personally I wouldn't worry about it, the car will compensate for the small changes.

I have also heard that its not really needed but I think I would still like one just for a little extra power

 

[nustang]

my understanding is there is a fuel map from Ford, and the ECM also has trim tables, that adjust for changes (fuel grade, altitude, etc) to keep air fuel ratio optimum when in closed loop operation (eg not wide open throttle).
So your O2 sensors will see any variance, and update the trim table if its within range of the ECM setpoints.

Doubt headers are going to flow enough through the original intake filter to need much extra fuel.

Another thing I understand is the fuel map is optimized for economy and EPA.
Getting a dyno tune on a live local dyno, where the shop can roll it and adjust ... re-roll etc after you have done all the mods you are going to do (even a plain stocker) will get you more power, but lock you into premium fuel, and lower fuel economy.

Id only do exhaust for : different sound, or more flow to support bigger mods at the intake, not on a stock setup.

 

[K4fxd]

eg not wide open throttle

These cars run closed loop except for start up. They are equipped with factory widebands.

Another thing I understand is the fuel map is optimized for economy and EPA.

These engines run stoichiometric at all times except for WOT. They do have logic for accelerating and decelerating.

The fueling I was referring to in my first post is some logic Ford uses to compensate for the widebands getting old. It uses a compare against the rear sensors to make small corrections to the front sensors.

 

[Cordero1]

Also to avoid the CEL which I've been driving around with for months now.

 

[WildHorse]

Can someone explain why the S550 needs to be tuned with just a simple header swap??

You don't.

Some think it is needed because the rear O2 sensors are no longer contributing to the fueling.

Huh ?

 

[K4fxd]

Huh ?

It's called FAOSC, or Fore Aft Oxygen Sensor Control

 

[WildHorse]

It's called FAOSC, or Fore Aft Oxygen Sensor Control

THought it's only job was to monitor cat efficiency. Lund Sr already explained it (rears) doesn't affect fueling in any meaningful way whatsoever.

 

[K4fxd]

THought it's only job was to monitor cat efficiency. Lund Sr already explained it (rears) doesn't affect fueling in any meaningful way whatsoever.

On the coyote platform Lund Sr is wrong. Ford uses the rear o2 sensors like they do the LT fuel trims.

 

[K4fxd]

Your buddy Alex has a YT rant on it.

Although I'm pretty sure his rant is to please the EPA. Gotta do what they can to reduce the fine.

 

[WildHorse]

Ford uses the rear o2 sensors like they do the LT fuel trims.

And even if it does affect long terms, BFD. .. Cause AFAIK the only codes it's show is volt to high/low, inefficiency, blah blah. Nothing fuel related.

 

[K4fxd]

And even if it does affect long terms, BFD.

Like I said in my first post, I wouldn't worry about it. However the question was asked and I answered according to how ford uses the rear o2's and the logic behind it.

Now go troll someone else.

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