How Bout' a "Snow and Ice" tune

[cleatus12r]

Originally Posted by 907dave

Is there any harm by doing this? Shouldn't the engine noise level be similar on a cold engine as a warm one? Or are there other things influencing this? I realize that it wont be as quiet but damn this thing can get really loud. As a tuner how would you know when you have gone too far?

There isn't any real mechanical harm in "retarding" the start of injection when the engine's cold. As far as retarding the SOI goes, it's not really "retarding" since it's more accurate to say that it's just less advanced. A lot of folks sell quiet tunes....even PHP has a Whisper Mode. Incorporating less advance in both the Start Of Injection for RPM vs. EOT and the Start Of Injection Delay for EOT vs. ICP maps allows the PCM to delay the commanded injection event slightly for the thinner oil when cold since the whole reason that map is there is because of the oil viscosity along with slower combustion rates and longer ignition time. Using 5W/40 oil when cold results in a "faster" injector than one utilizing 15W/40 at the same temperature therefore less advancing of the timing is necessary.

The noise level will always be slightly higher with a colder engine because it is working harder just to stay running. The drawbacks to not enough injector "lead time" when cold could be harder starting, white/bluish smoke, and sluggish performance. It takes quite a bit of "less SOI advance" to get these drawbacks so once you get to the hard starting or smoking, you've gone too far with that particular truck. Too much SOI advance is definitely audible and it's something that should be avoided for fear of a junk engine.

If you've ever heard of people recommending being easy on the engine while it's cold, it's because of these EOT related maps. There is A LOT of "advancing" going on there. Add into that the increased SOI of aftermarket tuning (RPM vs. Mass Fuel Desired) and you get some pretty awesome timing.