Originally Posted by cleatus12r (Post 17545)

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.

Originally Posted by 907dave (Post 17605)

For me the truck gets extremely loud during cold startup and easy driving even after extended idle time. I realize that the EOT is not up to temp yet which is why it is like this, but it really does not sound healthy at all. It has really concerned me. Keep in mind that I am running Hybrid injectors and know that it will never be as quiet as it was with the split's in there. I think you've realized the biggest issue. Yes, single shot injectors will inherently cause more combustion noise than split shots due to one big bang rather than the softened blow of two smaller injection events that makes a split shot what it is.So if I understand correctly if the truck is properly tuned when cold the idle and cruising noise levels should be similar to when the truck is warmed up? Not totally true, but the truck shouldn't sound like a 6.5L Chevy. If you've ever heard one of those, then that's what you don't want.And its possible that I can be doing more harm to the engine with this (advanced SOI) than I could be with it less advanced? Most of the time, this is the case. Later SOI will almost always be easier on the reciprocating assembly than earlier SOI to a point. Too late to the point of causing white smoke will wash down the cylinder walls with raw fuel and get rid of the oil barrier on the piston rings. It will also cause a severe lack of power, higer EGT (if a complete burn is accomplished), and just a waste of fuel.The white/blue smoke does not bother me much as I no longer have the intake air heater, fuel heater, or EBPV anymore and those all aid in reducing that. EPA probably wont like me much but I dont mind.

Ok, so how about doing the same thing (lessening SOI) on a warm engine to reduce engine noise. What adverse effects would that have. I would assume higher EGT's and poor economy, anything else? Would be nice to have a tune for city driving where economy and EGT's are nut much of a concern anyways.

Sorry, I am green at this and trying to get a handle on things.

Originally Posted by 907dave (Post 17648)

would the Romulator be worth getting with the Minotaur package?