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Message: [QUOTE="Power Hungry, post: 290888, member: 1375"] Here are some screen shots of the tuning curves from the 540 HP program as produced through [URL="http://www.gopowerhungry.com/_analytune.shtml"]AnalyTune[/URL]. Samples are taken at 190º EOT. [SIZE="4"][B]Injection Control Pressure[/B][/SIZE] [SIZE="1"](click on image to enlarge)[/SIZE] [ATTACH=full]83049[/ATTACH] [SIZE="4"][B]Injection Pulsewidth[/B][/SIZE] [SIZE="1"](click on image to enlarge)[/SIZE] [ATTACH=full]83050[/ATTACH] [SIZE="4"][B]Start of Injection Timing[/B][/SIZE] [SIZE="1"](click on image to enlarge)[/SIZE] [ATTACH=full]83051[/ATTACH] Keep in mind that these are "[B][U]DESIRED[/U][/B]" values. While SOI and PWM values are consistent between desired and actual, ICP values may vary depending on the capability of the HPOP. It is extremely important to look at the generated values from the datalogs to ensure that the "DESIRED" values and the "ACTUAL" values correlate. Also keep in mind that this is done WITHOUT forcing a maximum SOI Limit like some other tuners do (usually around 35º BTC). This means that this vehicle will run just as well when cold as it does hot. Under normal circumstances, the ECM will advance timing considerably when cold. For example, at 50º F, the SOI Timing curve would look like this... [SIZE="4"][B]Start of Injection Timing @ 50º F[/B][/SIZE] [SIZE="1"](click on image to enlarge)[/SIZE] [ATTACH=full]83052[/ATTACH] This is the difference between the two files.... [SIZE="4"][B]Start of Injection Timing @ 50º F vs. 190º F[/B][/SIZE] [SIZE="1"](click on image to enlarge)[/SIZE] [ATTACH=full]83053[/ATTACH] The SOI Timing difference is considerable, and clamping the SOI on vehicles that run in colder climates can translate into noticeable cold-start and cold running issues, excessive white smoke, and considerable loss of performance until the engine reaches normal operating temperature. These engines need advanced SOI Timing when cold to offset the low compression temps, cold air charge, cold fuel spray, and even the inherent injection delay cause by the increased viscosity of the cold oil. Obviously, the best approach is to let the PCM handle the SOI in the manner in which it was designed for the best drivability in all situations. :D Enjoy! [/QUOTE]