WOT A/F Seen on a Stock 5.0 GT

GT Pony · Apr 1, 2016

I was out driving tonight and had a few chances to really get on it with some long pulls at WOT. My car is a bone stock 2015 5.0 GT. I was watching the virtual A/F ratio gauge on information display during the pulls, and saw it actually dip all the way down to between 10~10.5 A/F ratio. Running 89 octane.

Seems a bit rich on the gauge, even for WOT ... guess I don't have to worry about it running lean. But maybe the A/F gauge isn't that accurate? I would think it is, as it's monitoring the wide band O2 sensors on the car ... right?

Anyone else ever note the A/F on a long WOT run on a completely stock 5.0? My car runs very good, and inside of the exhaust tips are spotlessly clean. I'm sure it must be normal but just wanted to see what others have seen.

DarkestHour · Apr 1, 2016

Probably some form of cat overtemp protection.

Orgalorg · Apr 1, 2016

What exactly is normal operating range?

jasonstang · Apr 1, 2016

89 Octane might cause some knocking so the computer is protecting it by running rich.

cbrtrx · Apr 1, 2016

DarkestHour said:
Probably some form of cat overtemp protection.

Correct, complete normal fueling when in COT. Nothing to worry about.

wildcatgoal · Apr 1, 2016

89 octane is a gimmick, IMHO. Just use 87 or 91/93.

09jsw · Apr 1, 2016

jasonstang said:
89 Octane might cause some knocking so the computer is protecting it by running rich.

It would just pull timing.

Gibbo205 · Apr 1, 2016

Mine is 11.9/12.0 at WOT stock car running octane 94.

Sasuketr · Apr 1, 2016

Stock tune with Steeda intake here, WOT A/F is at 12, running 91 octane.

Higgs Boson · Apr 1, 2016

Gibbo and Sasuketr I'd be interested to see your tunes. No ethanol in uk right? I wonder if ford uses 14.1 or 14.7 for stoich over there. Both at 12.0 at WOT on stock tune is interesting.

That would tell me they use 14.1 for both and let trims pull the uk cars back to 14.7...

VTECSAUCE · Apr 1, 2016

wildcatgoal said:
89 octane is a gimmick, IMHO. Just use 87 or 91/93.

Mid grade is a 50/50 mix of regular and premium. Not sure how that makes it a gimmick. I wouldn't run regular on a car with a 11:1 CR. You spent the extra money on the v8, why cheap out on fuel?

Higgs Boson · Apr 1, 2016

VTECSAUCE said:
Mid grade is a 50/50 mix of regular and premium. Not sure how that makes it a gimmick. I wouldn't run regular on a car with a 11:1 CR. You spent the extra money on the v8, why cheap out on fuel?

Which is why you run 93....every new car will benefit from premium fuel. Old cars with fixed spark may not. Those days are over.

VTECSAUCE · Apr 1, 2016

Higgs Boson said:
Which is why you run 93....every new car will benefit from premium fuel. Old cars with fixed spark may not. Those days are over.

That's exactly why I run premium from nation wide gas stations, ie Shell, Sunoco, chevron, mobile, etc.

GT Pony · Apr 1, 2016

Thanks for the comments so far. I'll fill-up with 92 octane next time and see if that changes what I see with WOT pulls.

Gibbo205 · Apr 1, 2016

Higgs Boson said:
Gibbo and Sasuketr I'd be interested to see your tunes. No ethanol in uk right? I wonder if ford uses 14.1 or 14.7 for stoich over there. Both at 12.0 at WOT on stock tune is interesting.

That would tell me they use 14.1 for both and let trims pull the uk cars back to 14.7...

Its still running Ford factory tune. How can I pull the tune of the car?

WOT A/F Seen on a Stock 5.0 GT

GT Pony

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DarkestHour

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