Diablosport Forums

What is the performance difference between the Diablo tune and the 91 octane tune?
I have a 2009 Corvette LS-3 and want to load the best performing tune.

I don't have a Vette but I know for my Silverado, the "Diablo Tune" is for use with 91-93 octane fuel. I would think it's the same with every other vehicle because the timing advance is set for the higher octane rating.

for the vettes, the Diablo Tune is made for 93 octane gas or higher... it has more timing/spark advance than the 91 octane tune does, and give a little better performance for the higher octane fuel used in the car...

and yes BlackZ71 - the Diablo Tune for trucks is made for 91 octane... but the car tunes are different - they have 91 and 93 octane specific tunes...

Thanks for the information as I wanted a tune with a better shift and spark curve.

I just finished installing Kooks long tube headers and high flow cats along with a Callaway cold air intake so I wanted to start with a more aggressive tune. I know the fuel slope will have to be enriched considerably so I will start at 8% and check the lift. I think I will end up around 10% with the changes.

Jlencioni wrote:Thanks for the information as I wanted a tune with a better shift and spark curve.

I just finished installing Kooks long tube headers and high flow cats along with a Callaway cold air intake so I wanted to start with a more aggressive tune. I know the fuel slope will have to be enriched considerably so I will start at 8% and check the lift. I think I will end up around 10% with the changes.

For you a custom tune will work tons better.

smokestack wrote:

Jlencioni wrote:Thanks for the information as I wanted a tune with a better shift and spark curve.

I just finished installing Kooks long tube headers and high flow cats along with a Callaway cold air intake so I wanted to start with a more aggressive tune. I know the fuel slope will have to be enriched considerably so I will start at 8% and check the lift. I think I will end up around 10% with the changes.

For you a custom tune will work tons better.

yes, definitely! ^ ^ ^

that much change to the injector slope setting for the fueling is not good...

you will make it too rich by adjusting the injector slope that much - and the car will feel like a slug - the MAF sensor tables need to be adjusted instead...

and why start with an adjustment BEFORE you even do a log?? don't make blind changes - do a steady driving data log FIRST... AFTER you have gotten about 100 miles put on the tune - because the fuel trims need time/miles put on in order to get relearned and settle in before the data will be correct/accurate...

you will definitely want to get a custom tune done for your predator/car/mods... but, it's up to you man...

with a custom tune for your car/mods, you'd gain even better/quicker throttle response and acceleration, stronger/harder pull, and usually even a little better mileage too... if you're interested in a custom tune, let me know, I can hook you up...

I already had run log before making the fuel slope change and the lift indicated a 9% increase over the 3% I had installed. You are correct I do not have the programming tools to access MAF table program in the ECU to properly develop a tune myself I only wanted to get it close enough to drive without hurting anything. I thought 11% was excessive so I installed a 6% as a test and created a log and it was too lean so I now have the slope set to 10% and everything is happy as far as error codes but I would not call this tune a keeper.

I am going to take it to a shop and placed on the dyno to get a custom tune for the modifications as soon as I find one I feel comfortable with.

If you have a shop you would recommend in the Kansas City Are please provide it to me.

I very much appreciate your comments and advise.

10% is too much... I wouldn't set it any more than 5%... doesn't matter what your average ltft's read at this point.. the 5% setting is still better than stock, and won't be too much as to negatively affect the vehicle's performance - it will still be better than it was...

I'm not sure about any diablosport CMR custom tuner dyno shops in Kansas City... but I know I can get you dialed in all via email....

if you want to look for possible diablo tuners in your area, use the dealer locator to find a few and give them a call...

Thanks I will make a few calls.

I was getting low cat efficiency and lean engine error codes when I had the slope set at 6 % and those have gone away since I increased the slope to 10 % are you sure I should change back to 5 %?

I know the MAF and VE tables are not correct since the changes and that is what is causing the wild slope readings so I really want to make sure the folks I go to really understand the complexity of the tune and take the time to do it correctly.

Just a little history I installed the headers first and the 5 % was fine and the car really responded but since I installed the Callaway cold air it pushed the MAF off the charts. Your diagnosis is right on and correlates with all the research I have made.

Thanks again.

You're getting those trouble codes because of the headers... Those codes need to be disabled in the tune file when adding long tube headers, removing cats, etc...

I am running the 91 octane tune on a '05 vette. Just put an LG long tube header with high flow cats on it and now I get a P0171 (bank 1 too lean) code. What is the best or easiest fix for this? Any suggestions.

need to get a custom tune done in order to get the fueling adjusted correctly and to disable the necessary trouble codes...