O2's oscillate. All but that RT bank, Sensor 2. It lags behind. Ya, I shoulda said only 2, the fronts, cause I had thought of deleting rear O2's anyway. Kinda tired, only had 1 1/2 hr. of sleep last night.
I'm tired of seeing my SES just cause of that 1 particular O2.

I'm kinda assuming since my brother had similiar mileage & they smelled of gas, looked oily, & the gaps were outta whack, I was in the same boat.

I'm beginning to believe that is true on the higher temps on Gen3 & up motors.
I can't really comment on the FI part since I'm currently N/A. I had thought of throwing my old "stock" stat back in to see if mileage went back up, back there are 2 problems I see w/. that.

1) It's cold here now, I'm not in TX, & I hate doin anything in winter except oil changes & tire rotations( not real crazy bout those in cold, but I did both yesterday).
2) Gettin coolant all over. :( :cry: That's why I did the efans when I did my water pump gaskets, I can't stand coolant all over & only wanted to deal w/. that mess once.

Reason I wanna throw stock stat back in, is I'm curious & started faulting efans as the culprit, when they're in all likelihood not at fault. I thought a cooler stat would add power. My guess is, they only add power if timing is tweaked. Also, prior to w/p gaskets replace/ efan & 160* stat install, I found 3 of 4 counts on my histolog of knock. It only occurred for maybe 3-5 seconds tops, when hammering it ~70MPH, going up to 75MPH. I never had that before, but at the time, low coolant wasn't doin me any favors. It was right aftere I took a 1300 mile trip. However, I know now after I did gaskets/ fan/ cooler stat, it still has some knock. That bothers me, even if it is only under really hard accel at/ around that speed under load.

One thing i did find that could be causing your MPG drop is the dynamic (transient fueling) setting are different... Transient fueling occurs anytime your increase or decrease the throttle, even very slightly.... There are variations between 212,194,176,158. looking at the table the cooler your go the richer it gets...

Just an example:

Normal temp ~ 204*
The impact factor is 0.2195

With the 160* stat, your probably running ~167*
The impact factor is 0.2715

That is roughly a 23% increase in fuel when you increase the throttle... Not to mention the duration of the increase lasts alot longer the colder you go as well....

I am not going to do the calcs for how long the fuel stays on the wall and all that jazz or the decel richness stuff, but all of the setting increase (go richer) the cooler your truck runs...















NOW, i would really like to know what most people got tuned, when they said they are tuned for a colder thermostat, besides the FI guys... Because from what i posted previously none of the main spark and fuel tables are affected, except the transient stuff.... And i bet 90% of the people who own tuning software have no clue about transient settings....

I would be part of that 90%........:confused:

:thumb: Sounds like you're onto something. 23% could definitely hurt. :ripped:
I just laid the tables into my HPT that Whippled 496 used as far as fan & temp settings, & I enabled the 2 fans.

Other than that, no changes whatsoever to spark & fuel.

I just wanted to get it running, so to be a 100% effective tune, it definitely needs fuel & spark to make it right. :bang:
Fuel & spark are beyond my current skills.
I'm w/. Roger, I'm part of the 90%. :D

Update: I tuned fans to come on at higher temps, & believe it's makin a diff in MPG. Previously, it was prolly just too low.

Fan2 on/off: 195/ 188
Fan1 on/off: 190/ 183

I'll try this awhile. See what that gets me. Go thru a few tankfuls of gas to get an idea. I'm even toyin w/. idea of raising close to stock for winter, cause it heats cabin fine & it's plenty cold outside, so no worries there. :judge:

My truck cruises at 163* no matter what, unless it has a trailer on it. And a lot of days the fans never come on, even in Tx (Mine are set something about like yours I think) Yesterday with a 24ft car hauler with a sandrail car and LOTS of parts it cruised @ 70mph, and 172.

Get a wideband on it and work on lean cruise cells in your VE, I have seen the best results cruising between 15.8-16.0 and 33-34 deg timing (at cruise) I've seen more than 20mpg more than once. I believe I averaged 17ish mpg last tank with LOTS of city driving. Yeah, there's a 4.8 in the truck for the time being but there's still 65# injectors, a couple big fuel pumps and a 78mm turbo hanging on the side of it. ;)


Dialing your fuel in is all around the best way to improve your MPG IMO. If you're not comfortable yet doing that, read up and try some stuff. Or let a competent tuner do it... But no matter what, from my experience, a tuner won't put the same time and effort into making your setup run right as you will.

I've only had my 160* stat in the truck for a couple of weeks; it's not my daily driver so I'm still learning how the new stat is going to run in various traffic conditions. My FAL's are set to come on at 195*. I got into some heavy stop & go traffic Friday night on the way home from work and the coolant temps hovered up around the 195* mark. The fans never came on; the outside temperature was somewhere around 48*. So far it appears the temp is going to run at around 180* when running down the highway.

As far as gas mileage I can't say yet. I'm still working on idle tuning, etc. since the cam install. At this point I don't see any significant difference on the gas gauge, based on knowing how the gas gauge vs. mileage has worked in the past. Of course, I might be stepping on the gas a little more than normal right now with some newly found power!

The transient fueling theory is interesting; I've looked the tables over while in the programming but that's as far as I've gone.