I did my first dyno Saturday. It was a "Dyno day" setup. They did 2 pulls. The tech told me I needed to get more air into the engine. Initial A/F at 2K was 14.53/1. At 2200 it drops to 13.54/1 and stays between 13.20 and 13.60 all the way to 6K. MAX HP was 276 and MAX Torque was 290. I'm running a 80mm Steeda CAI with a stock tube and Steeda 91 Octane Predator tune. Most of the other 05 and 06 cars didn't drop out of the 14s until 4K. My question is what is normal and what is bad.
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PARIS-05 GT Vert Auto Torch Red 290 RWHP 18x9 Chrome Bullitts 255/45/18 Silver cam covers Carbon fiber/billet/chrome dress ups C&L w/Predator 3D Carbon Tonneau Cover Flowmasters.
14 is on the LEAN side, on a general basis, a ratio of 12.6:1 to 13 is fine on a naturally aspirated engine. Leaner mixes tend to increase combustion temperatures.
I'm assuming by looking at your sig that the pulls were done with the Predator tune? Those are some fairly lean numbers for a canned tune. Did you mod with any additional power adders that are not accounted for in your tune? I wouldn't be surprised if your CEL went on soon. I'd have a tuner take a look at that graph.
Yes - I bought the Predator from Steeda with the appropriate tunes for my Steeda CAI. The only things I changed in the tune were the rev limiters. There are no other power adders on the car. I've been running the tune for about two months now with no problems. The tech doing the pull said he thought he heard detonation. I'm deaf in one ear and with the sucking sound from the intake and the growl from the magnaflows I'm pretty much oblivious to anything else. My predator will allow me to adjust the air/fuel mixture. I'm comfortable with richening it up a bit.
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PARIS-05 GT Vert Auto Torch Red 290 RWHP 18x9 Chrome Bullitts 255/45/18 Silver cam covers Carbon fiber/billet/chrome dress ups C&L w/Predator 3D Carbon Tonneau Cover Flowmasters.
I did my first dyno Saturday. It was a "Dyno day" setup. They did 2 pulls. The tech told me I needed to get more air into the engine. Initial A/F at 2K was 14.53/1. At 2200 it drops to 13.54/1 and stays between 13.20 and 13.60 all the way to 6K. MAX HP was 276 and MAX Torque was 290. I'm running a 80mm Steeda CAI with a stock tube and Steeda 91 Octane Predator tune. Most of the other 05 and 06 cars didn't drop out of the 14s until 4K. My question is what is normal and what is bad.
Where were they measuring your A:F ratio? If they just stuck a probe into the tailpipe downstream of the cats you may have not gotten accurate readings. The exhaust needs to be sampled before the cats. Also, what does "get more air into the engine" mean? If that means more air in relation to the given amount of fuel, that will make your A:F even leaner and then you'll have real problems. You've already eliminated any significant intake restriction by installing the Steeda CAI, so the only way to "get more air" is to add a supercharger. If those figures are accurate you need to add fuel, not air. That sounds like a typical meaningless motorhead comment.
Stoichiometric ratio is 14.7. As long as you are at that number or lower, you should be fine.
And as someone else mentioned, if the measurement is being taken downstream of the cats, it's worthless. A true reading taken before the cat should swing back and forth between lean and rich as the O2 sensor continuously adjusts the mixture.
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Stoichiometric ratio is 14.7. As long as you are at that number or lower, you should be fine.
And as someone else mentioned, if the measurement is being taken downstream of the cats, it's worthless. A true reading taken before the cat should swing back and forth between lean and rich as the O2 sensor continuously adjusts the mixture.
A:F of 14.7:1 with an oscillating reading is only applicable during closed loop operation. At full throttle you are in open loop mode and need excess fuel for maximum power, near 13:1.
Thanks for the replies guys. I do believe they monitored it at the pipe. There was a wire running into the engine compartment but it was just a clip on lead. I couldn't see where it was attached because the car was on a lifted ramp. The "more air" comment got me too. The only thing I could think of that he might have been talking about was the early drop (in relation to the other 05s) out of the 14.5 range.
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PARIS-05 GT Vert Auto Torch Red 290 RWHP 18x9 Chrome Bullitts 255/45/18 Silver cam covers Carbon fiber/billet/chrome dress ups C&L w/Predator 3D Carbon Tonneau Cover Flowmasters.
Very true.... If they were using "sniffers" in the exhaust then your reading may not be accurate at all. Good point. I still for some reason assume that all people operating dyno's know what they are doing
A:F of 14.7:1 with an oscillating reading is only applicable during closed loop operation. At full throttle you are in open loop mode and need excess fuel for maximum power, near 13:1.
For maximum power, yes. But that wasn't the point. 14.7:1, even at WOT, won't harm the engine, it's just sub-optimal for power.
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Thanks for the replies guys. I do believe they monitored it at the pipe. There was a wire running into the engine compartment but it was just a clip on lead. I couldn't see where it was attached because the car was on a lifted ramp. The "more air" comment got me too. The only thing I could think of that he might have been talking about was the early drop (in relation to the other 05s) out of the 14.5 range.
The clip on lead went onto one of the plug coils to detect when the plug was firing. It's how the dyno gets a reading of engine RPM.
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My first dyno pull the fuel/air was in the 14's also, but did another run at open loop WOT and it was around 12-13. I have the C&L and preditor 91 tune, it did 293/303
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For maximum power, yes. But that wasn't the point. 14.7:1, even at WOT, won't harm the engine, it's just sub-optimal for power.
Actually that was the point, ie. "what is normal and what is bad?" During full throttle, open loop the O2 sensor is out of the picture. Thus there is no feedback and the A:F is determined solely by the fuel map, assuming that fuel pressure is normal. No one is his right mind would tune an engine to achieve a WOT A:F of 14.7:1. EGT would skyrocket and pistons would melt and/or be hammered by detonation.
My first dyno pull the fuel/air was in the 14's also, but did another run at open loop WOT and it was around 12-13. I have the C&L and preditor 91 tune, it did 293/303
I have that set up on my vert. I'm going to dyno it at a different place (JBA) next month. Your numbers give me a target range. Is yours a stick or an auto?
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PARIS-05 GT Vert Auto Torch Red 290 RWHP 18x9 Chrome Bullitts 255/45/18 Silver cam covers Carbon fiber/billet/chrome dress ups C&L w/Predator 3D Carbon Tonneau Cover Flowmasters.
Air Fuel Ratio - What is normal and what is bad? 
