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2003 S281SC Stalls on Deceleration

Old 06-24-2018, 11:28 AM
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Join Date: Jun 2018
Location: Wisconsin (WI)
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Post 2003 S281SC Stalls on Deceleration

I have a technical issue I need help with, I don't need to know if I will get my hands dirty changing an oil filter, or where the headlamp switch is.
I have an issue with a 2003 Mustang GT, with a 4.6L Supercharged S182SC from Dearborn. (Automatic Transmission, 34,000 miles)
The engine stalls on deceleration for a yield, a stop light, or exiting a highway on an exit ramp. Not hesitation. Clean shut down, as if the ignition was turned off, and starts immediately (once put into park), as if she were shut off, with no excessive cranking. (Hit the key and she starts)
The engine is not coding anywhere. I've smoked her for vacuum leaks and repaired the one I had beneath the supercharger plenum.
#1 bank is reading lean. #2 bank is reading rich. Cats and O2 sensors were replaced at 14,000 miles.
Has anyone else had this problem and come up with a solution?? I'm not into part swapping for the joy of it.
I've been reading it has been an issue for at least the 15 years this car has existed. I've also heard Ford has had bulletins out on the issue. "Do They"??
Any relative suggestions?, Or "the/a" technical resolution that might exist?, Or a technical summation for this kind of a failure?
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Old 06-25-2018, 01:35 PM
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Only thing that comes up from my research is either a timing issue or the front O2 sensor connectors are swapped. (left connector on right side/right connector on left side).

Did you get a reading on your LTFT and STFT (Long/short term fuel trims) to see just how lean/rich the two banks are?
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Old 06-25-2018, 02:58 PM
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Thank You for Responding so Quickly, Derf.
The front O2 sensor on Bank #1 is coding. It shows that that Bank is running rich, although the Bank Trim shows Bank #1 to be running lean.
The Trim on Bank 2 shows a rich condition. Should I be seeing a fault somewhere that is causing the overloading on Bank 2?

I am in the process of getting, and replacing, the bad sensor and will run the car again. I'm also curious about the condition of that Cat now, and the back pressure on that side and will check it. I will also make a point of checking the connections on your recommendation.

The Cats only have 20,000 miles on them, but I don't know the extent of damage due to any overload conditions. She did have two vacuum leaks that I just resolved.

I'll also make a point of checking on the timing. I played with the idea that there could be an issue with the cam sensor, OR the crank sensor. Do you have any thoughts on that??

Once again, Thank You for responding, and for your input. It gives me some ideas to run with. This issue has been going on far too long.

Do you have any other thoughts? I've been reading about flashing updates and TSBs that I can't seem to find. (My Ford dealer, here, doesn't even want to look at the car regarding "anything" because she's supercharged. (Even though Dearborn put the motor in, as is, from a crate).)
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Old 07-05-2018, 06:13 PM
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Default Here's the Scoop if You're having tis same Problem...

First, I'd like to thank you again Derf. You were on the right track with your advice about the O2 sensors.
I replaced the one I had said was coding, and checked the flow of the Cats. The Cats were fine.

I did check the connections on the O2 sensors, in the event thay had been crossed, but the wiring checked out fine.
When I last wrote, I had mention how Bank #1 was reading Lean, and Bank #2 was reading rich.
Once I replaced the O2 sensor on the #1 Bank, that Bank began reading rich to match Bank #2.

It ended up that the injectors were being held open to long by the ECU.
Apparently the wrong program (file) was programmed into the ECU from/by/at the factory.
The issue with the car stalling required an updated flash to meet the engine spec. ("Not" the factory generic "line" spec.)

I requested a file update directly from Saleen. The flash cured the problem.
Once I cleaned up the tune on the engine the car no longer stalled/stalls.
Power has also increased considerably.

If someone else out there is having this same problem, check the O2 sensors (as Derf recommended) and then check the trim.
You may be overloading the injectors by an elongated duration communicated from the ECU, and may require an updated flash to mate any original ECU commands to the engine the factory put into your car. It may take you some research.

Thanks again Derf.
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