Correct air/fuel ratio?

[nearmiss]

Can anyone out there tell me what air/fuel ratio should be measured during a dyno run? I had thought that the correct ratio was 14.7:1. My car measures between 11 and 12 to 1 during the dyno run which seems rich. The engine is a stock LT4 with an K&N, shorties and a B&B exhaust.

Thanks!
Nearmiss

 

[Ken]

The ECU and ECM are constantly trying to maintain a fuel/air ratio of 14.7:1, or as close as possible. Have you done any re-burns on the chip since the installation of the aftermarket goodies?

 

[nearmiss]

The ECU and ECM are constantly trying to maintain a fuel/air ratio of 14.7:1, or as close as possible. Have you done any re-burns on the chip since the installation of the aftermarket goodies?

I haven't reprogrammed the ECU/ECM. The headers were on the car when I bought it. It originally had a pretty trashed out set of flow masters which I replaced with the B&B's, but otherwise I haven't done anything extra to the engine. I'm pretty sure it doesn't have any real goodies since its only putting out around 300 hp, which seems typical of an LT4.

 

[Dammit man]

Does the Hypertech module change the ratio?

 

[stgry1]

Does the Hypertech module change the ratio?

I'd be real interested in the answer to this if anyone knows it. I had a REAL bad experience at the dyno last weekend. I ended up reseting the ECM from the hypertech and gained 15RWHP. :W Can you believe that??? I was mildly upset to say the least. I am considering the LT1 edit program now so I can do it the right way all the time....any time.

 

[Vettelt193]

I'd be real interested in the answer to this if anyone knows it. I had a REAL bad experience at the dyno last weekend. I ended up reseting the ECM from the hypertech and gained 15RWHP. :W Can you believe that??? I was mildly upset to say the least. I am considering the LT1 edit program now so I can do it the right way all the time....any time.

some people swear by re-setting it before doing any racing... if you are cruising down the highway, the computer is working on getting you max gas mileage... by resetting it and immediately running it hard, the computer will move to full performance mode.

A perfect example of this is on my way to the track Vs. the way home. I will easily get 5 MPG less on the way home on the highway than the way to the track, while the car re-adjusts to get better gas mileage.