Blower Pulley Change? Air/Fuel problems?

EvilEyez said:

I got an 03 Snake with a Bissani Xhaust, pro 5.0 shifter, and a drop in K&N. I was thinking of upgrading to 2.93 pulley, but I've heard that you need some tuning to get Air/Fuel right. Does any one know how well the Diablo Predetor works? Has anyone had any problems after a pulley change? Some feedback would be great.

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The DiabloSport Predator is a good tool. It is NOT good enough to trust 100% though. You still need to verify any adjustments made with the Predator are safe on the car's A/F ratio. The Predator pulley tune should be used in conjunction with a wideband dyno just to be safe. There are a lot of guys who have added a 2.93 pulley and flashed their ECM with the Predator pulley tune. For many it has worked just fine. Then there are a lot of guys who had to get custom tunes sent to them. Their A/F ratio was far enough out the Predator couldn't compensate enough. The user is only able to add or subtract fuel a few % in either direction.

If you are unable to get to a dyno right away you could flash your car with a modified pulley tune. Modify the pulley tune before uploading it by adding as much extra fuel as possible and pulling a few degrees of timing. Once you flash the ECM listen for any detonation and get to a dyno as soon as you can.

U.M.

A couple of follow up questions:
1. Does the use of the Predator end warranty coverage?
2. I understand the Predator has the capability of storing the OEM program, which can be reloaded back into the computer if dealer service is required - thereby leaving no trace of the changed program. Is this true, it really erases all evidence of a reprogramed computer?...

terrydf said:

A couple of follow up questions:
1. Does the use of the Predator end warranty coverage?
2. I understand the Predator has the capability of storing the OEM program, which can be reloaded back into the computer if dealer service is required - thereby leaving no trace of the changed program. Is this true, it really erases all evidence of a reprogramed computer?...

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1. Yes it very well could! If Ford were able to prove you used a Predator to load a tune into the ECM that directly related to the warranty claim in question. Example, you accidentally load a bad custom tune into the Predator that has the A/F really lean. You burn a piston. If Ford could prove you had a custom tune in the ECM, and that's what caused the #7 cylinder to go, then your powertrain warranty would most likely get voided on the spot.
Of course this would be hard for them to prove because...

2. Yes. The first time you connect the Predator to your car it makes an exact copy of your stock tune and stores it in the Predators on board memory. Now if Ford were to examine your ECM while it had a Predator tune in it, could they tell? Yes, if that's what they're looking for. Now if you flash the ECM back to stock, and then Ford examines the ECM again, can they tell if there WAS a Predator tune installed? No.

U.M.

So what A/F ratio is considered good, without risking over lean problems?

terrydf said:

So what A/F ratio is considered good, without risking over lean problems?

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Optimal A/F ratio on the '03 Cobra is between 11.5-11.8.

U.M.