Join Date: Feb 2005
Location: Atlanta, GA
My Ride: CSX/CS/GLHS
Thanked 0 Times in 0 Posts
Re: Power drop at full open throttle!??
I am truly trying to not come off as flippant....but it's just not realistic to expect that in an electronically controlled fuel injected car that you can change to a larger turbo, add higher flowing fuel injectors, put on a larger exhaust and then expect the 25 year old factory "hard coded" computer to still do the air/fuel mixture correctly under all circumstances or to not introduce a quirk or two or some strange drive-ability concern. It's just a fact that most 'newbies' to fuel injection are just not told this and then when they get the wide-band and discover the tune is off, eventually it comes to mind the reality of NEEDING a custom tune.
Like WELL DUH!
We really should have a FAQ or at least add notes to our standard stage I, stage II, stage II build FAQs that if you change anything in the 'system', then the likelihood that you are going to require a custom tune is going to be somewhere between 50-100% depending on how far you go. And as seasoned turbo Dodge Wizards we have a unspoken responsibility to spread the word that one change forces another and modifications upset the system balance and it may need to be re-balanced.
It should just be a given, and frequently broadcast to those thinking about modifying their cars that the factory built a balanced system, they spent hundreds or thousands of hours on the dyno, in endurance testing, millions of dollars and blew up a truck load of engines getting it right, or right enough to make it all the way through the warranty period...and they did it all with some of the most talented and well educated and experienced minds in the automotive industry. But still a lot of it was indeed trial and error. No big deal if you have a pile of engines and cars to play and experiment with. A different matter when the car might be your daily driver or one you need to rely on to not blow up when you are not on the track where blowing the engine is a 'well I guess I pushed it a bit hard' event.
Off the shelf custom tunes included, that most assume a very specific recipe of parts are being used, and if you deviate, then the system is again not well balanced. Not to pick on any body's tune, but if you buy a stage III from vendor X and it says for stock motors with maybe a 2.5" or 3" exhaust, and you then throw in +20 injectors and maybe a ported exhaust manifold or a 52mm throttle body or decide to run a octane booster or meth injection, remove the EGR, or any of the dozen other HP cheats...well then that tune is no good for you. The tune is what it is and it assumes a specific configuration. When you go even higher like to a stage 5, then the requirement for other system changes is also a given (like a AFPR, larger exhaust, +40s, etc.) and again if you don't follow the recipe, it's gonna be off and you'll need a custom tune.
All that being said, if you want it to run right all the time, and you have made mods, then you are setting yourself up for learning more about the fuel injection on your car than you might have initially planned. Once you plug into that community of expertise, do the math and the homework, do your tests, learn how its done, then you are on your way to a good tune and a lot more fun per MPG. It just takes time and effort and expertise as well as the consult of those that have gone before you. Of course it helps to have a budget for rebuilding the engines you are going to blow learning.
Again, not wanting to come off as flippant, or pick on anybody, it's just somethings I felt needed to be said. Mess with the balanced system, perfect or not, and it's not balanced till you work it out again.