I am thinking of switching to a Custom Operating System and I would like to hear about peoples different opinions... A couple of reasons I want to do this. First trying to dial in the MAF is a huge PIA.... Running in Open Loop with PE feels so much better than normal Closed loop MAF... Also I want to command 15.5 in the cruise regions for some better MPG...

 

no need really for custom os(so some people say)...i run open loop speed density on my truck. cruise a/f is somehwere around 15.6...

 

OLSD and a Custom OS does give you more control over fueling and no loss of performance , but no real gain either on a N/A engine .
Makes people jealous when you say , "I'm running a Custom OS and OLSD tune" .
Justin where are you ? This guy needs your help again !

 

The only real benefit I found from some reading is that it gives you the low octane spark table back. Which in my mind would be great if you ever got a bad tank of gas or heaven forbid if I had to put some 87 in my truck.... I think some of the other options I think are a switchable tune for Nitrous, which I don't plan on running and a valent mode (might be the same as nitrous).

It just seems like it is sooo much easier to get the fuel I want in OLSD, no damn MAF table to worry about...

 

Do you need to adjust your tune every once and awhile for a changes in temperature (summer vs winter)?

 

I've been running in OLSD for while now too and I haven't really noticed enough of a difference with weather changes to worry about a retune.

 

i haven't had a wideband on it to verify but none of the trucks characteristics have seemed to change. still idles good, still getting 20+ mpg and WOT still feels great. i would think any changes it need would be minor...but i could be wrong. i'm going to install my wideband when i finish up my exhaust this week

 

what i like about the COS is the commanded fuel vs. rpm...seems to be easier to tune for MPG to me. i'm going to try and flash an 05 os in my truck then do a COS...just seems easier to me...

 

Don't know what it is but 04 PCMs seem to have a hard time with SD unless you use a Custom OS .
At least a friend had a hard time with SD and HPTuners and his 04 5.3L , might have just been the tuner though .

 

Do I need to keep DFCO disabled when I am finished tuning? The reason why I ask, is because when I come to a stop the idle dips pretty bad and dies sometimes when it is in OLSD