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Old 04-14-2012, 09:01 AM   #604
Ziggyrama
Scooby Specialist
 
Member#: 53665
Join Date: Jan 2004
Chapter/Region: NESIC
Location: Northboro, MA
Vehicle:
2022 BMW M240i
Thundernight

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Quote:
Originally Posted by dux10 View Post
So when you tune a car on the street/e-tune, how do you determine this "one perfect timing map"? I mean, afterall, every car and environment are different... So what do you do to set the car up for a cold day vs warm day or humid day vs dry day or a trip up to the mountains vs a cruise by the beach?
The ECU has provisions for this. Changes in atmospheric pressure and IAT are accounted for by comp tables. Based on what I have seen, a lot of "tuners" struggle with this concept. We read countless threads about setups that seem to be OK on the day when the car was tuned but as seasons change, the car goes all out of whack. Weak sauce. If you're tuning your car and you don't know how IAT and absolute pressure affects things, you need to stop and either educate yourself or hand the reins over to someone that can complete the job for you. I do not intend this as criticism, just advice that will save time and money. A smart person knows when they're in over their head and when it's time to call in the cavalry.

Quote:
Originally Posted by dux10 View Post
Tuning is not all science and will not always be "perfect." There's plenty of us that tune cars to a respectable AFR (not 11:1 all the time) with high boost (based on compressor charts, previous experience, and other research) and timing set to a level where knock does not occur under ALL conditions (e.i. aggressive driving, track, sustained 4th-5th gear pulls, etc..), that also explore other areas of the map that are used everyday such as part/light throttle, cruise, etc...
Tuning IS all science. Back in the day people though fire was magic and earth was flat Now we know better. There is a well defined science to how an engine needs to be managed and what happens when surrounding conditions change. There's a disturbing trend on this forum that implies that tuning is some kind of mysterious, black magic art. I think it comes from the fact that, to be frank, some science is above an average person's pay grade and people tend to have a mentality that if they don't understand what is going on, then the problem isn't with me, it's just magic. Now, don't get me wrong, and I want to ve very clear about this, tuning is not easy and I personally think most people should not attempt it. Like all other technically complicated topics, if you do not have proper background, you will likely not succeed. And even if you do have the expertise, do you have all of the tools to do it correctly? Consider what Subaru does when they develop an engine. What most people do is a poor substitute for the way it should be done. What is amazing to me is that a qualified person with limited tools can do fairly well but let's be clear about this, there is no full substitute for a proper tuning setup.
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