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Discussion Starter · #1 ·
O.K. You can see from my sig what I've added to my car. There should be a lot more air going in. I put the Predator tune in my car and when I checked my A/F it looks like this; Rich-----------------------+----------Lean. Does anyone know what this means? I've got an 18hr drive ahead of me and Meatball says if the car's running really lean I could toast my motor:happyhapp. Help Please, anyone with info, similar mods? Thanks in advance.
 

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Larry Sergent said:
O.K. You can see from my sig what I've added to my car. There should be a lot more air going in. I put the Predator tune in my car and when I checked my A/F it looks like this; Rich-----------------------+----------Lean. Does anyone know what this means? I've got an 18hr drive ahead of me and Meatball says if the car's running really lean I could toast my motor:happyhapp. Help Please, anyone with info, similar mods? Thanks in advance.
Was it a custom tune for your setup or just the basic tune for an all stock GT? If it was just a generic tune, then that is probably your problem. You've got a lot more air coming through your intake system than a stock GT.

Also, where in the powerband were you lean? If you aren't lean under light loads during low rpms, you can still drive the car. You just shouldn't go full throttle.
 

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Discussion Starter · #3 ·
Monkey Boy said:
Was it a custom tune for your setup or just the basic tune for an all stock GT? If it was just a generic tune, then that is probably your problem. You've got a lot more air coming through your intake system than a stock GT.

Also, where in the powerband were you lean? If you aren't lean under light loads during low rpms, you can still drive the car. You just shouldn't go full throttle.
Yea, it was the generic tune. This: Rich------------------+--------Lean, is what the Predator shows while sitting in my garage. No numbers. I just don't have time to get it dyno tuned before my trip. Do you think I can safely move the bar to a richer setting?
 

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Anyone? -- thanks
 

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You can add more fuel with the programmer by yourself. How much to add is a whole different question. You are going to have to experiement and find out.
 

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Discussion Starter · #6 ·
Monkey Boy said:
You can add more fuel with the programmer by yourself. How much to add is a whole different question. You are going to have to experiement and find out.
Thanks Monk. Do you know what symptoms I should watch for? How to tell leaness and richness?
 

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If a combustion is to lean the big risk is to have pinging (pre ignition).

This is caused by two factors:
- a lean mixture is more likely to self ignite by hot surfaces in the combustion chamber (for instance the tip of a spark plug, glowing carbon deposits, etc.)
- flame travel (the speed of how fast the combustion actually hapens) is faster at a 14.7:1 A/F than at a 13.5:1 A/F
14.7:1 would be the stociometric ratio where all the fuel atoms are getting burnt with all the oxygen atoms. But that's theory...

I say as long as you don't beat on your motor and you don't hear any pinging, you "should" be fine - unless there is no other problem.
Me personally I would do the drive, only on premium gas (octane booster) and then see my dealership ASAP.

But that's only my opinion.
 

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Just to play it safe I would throw in some extra fuel until you can get it to a dyno to check the A/F ratio. Also, you can retard the timing a bit to give yourself some leeway. It doesn't take much to prevent pre-ignition, 2-3% retard on the timing should do you just fine.
 

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Larry has gone to the full DeMolet setup: CAI, Dragon 75mm TB & Plenum - wouldn't the stock computer compensate for the increased airflow?
 

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NO! It won't. With just the intake and exhaust mods you see in my sig, my car went lean before the tune. It was fine right up til I put the plenum on, then the A/F ratio went to poop. I actually LOST 15 rwhp and 17 rwtq with it like that. With the tune, it went from 227 rwhp to 262 and torque went from 267 to 312. I highly recomment anyone with intake mods of that extent and especially with a modded exhaust to get a tune, or at least get the A/F ratio checked.
 

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OK, good, this is pretty much the answer we were looking for; can he change in Predator and run premium to help. Don't believe he has access to tune before trip. thoughts?
 

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He can make global changes to fuel and timing with his Predator to fix the lean condition.
 

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Discussion Starter · #13 ·
Monkey Boy said:
He can make global changes to fuel and timing with his Predator to fix the lean condition.
How do I do that? I set the a/f a little richer and it actually seems to run a little better, but I'm really looking for numbers that someone with a Predator has used. For example, on the Predator I went from 0.5 to 4 towards the Rich setting. Is this too much? Not enough? Numbers on any other settings would be helpful. Thanks alot.
 

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I don't have enough experience to help you with the specifics thatr you're looking for. My best advice would be to call a speed shop the does Diablo tunes and get a little more insight from them. I can tell you that if you're not hearing any pinging then you are more than likely just fine. I personally think that the change you made with the fuel table will be sufficient.
 

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Larry Sergent said:
How do I do that? I set the a/f a little richer and it actually seems to run a little better, but I'm really looking for numbers that someone with a Predator has used. For example, on the Predator I went from 0.5 to 4 towards the Rich setting. Is this too much? Not enough? Numbers on any other settings would be helpful. Thanks alot.
If its running better then you definitley took a step in the right direction. My advice: take her for a test drive and don't skimp on the throttle. If you notice some pinging, add more fuel the same way you just did. If not, leave the tune alone until you get back from your trip.
 

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Discussion Starter · #16 ·
Monkey Boy said:
If its running better then you definitley took a step in the right direction. My advice: take her for a test drive and don't skimp on the throttle. If you notice some pinging, add more fuel the same way you just did. If not, leave the tune alone until you get back from your trip.
Yea, did that today. Never really had any pinging. I just feel like something's holding it back. I'm hoping it just needs a good tune. I really wanted to finish the exhaust (Pro Chamber and Magnaflows or Magnapaks) before the tune.
 

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If there's no pinging, then go ahead and finish the exhaust and then get the tune.
 

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Discussion Starter · #18 ·
Great trip! Wide long straightaways with opposing lanes seperated by a 50-100 yd devider. Speed limit was 75 most of the way, set my cruise control on 77-78 and the stang just purred for hundreds of miles! 1600+ mi. actually. Tried the stock tune first. Yuk! Gutless! So I installed the Predator tune and flew! It was great! If you ever get the chance and haven't already, go see the Grand Canyon. Better yet, take the gourmet rafting trip through the canyon!
 
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