Cold weather and AFM

Silver space ship · November 12, 2013

So my AFM seems to be much more noticeable while transitioning after I had it recalibrated for a recall or TSB from the dealer. The one thing is, right about the same time the weather was starting to get cooler. Today was 12* and it took my truck 9 miles of 65 mph to go into V4 (right at 210* temp), no big deal the motor should warm up to operating temp before it shifts into v4 and that's what it did. The funny part is a few weeks back it was in the 30* and it would shift into v4 right out of my driveway in the morning, defiantly not up to operating temp. So even after it's warmed up to 210* the transition is not smooth, I'll be cruising along and when it switches it will actually make me jump a bit because it feels like you hit something or a hard shift from the tranny. All summer long it seemed only slightly noticeable. Just checking if anyone is experiencing this?

Another thing anyone else notice a couple mpg drop now that it's getting colder? After the recalibration I dropped about 1.7 mpg too, outside temps in the 30's but coming from a heated garage at 55* in the morning and by the time I would drive home it would be in the mid 40's. Seemed a bit steep for those temps and not letting it run to warm up. Now with temps in the teens I expect that much of a loss. This tank I'm looking at about 2.4 mph loss and like I said I'm not letting it idle. Then there's always winter fuel but I read that's only a 3% power loss.

2014 Sporty Shorty · November 12, 2013

Turn off your AFM and you won't have any more issues.

jay15892 · November 12, 2013

I hardly ever feel the V4 mode engage. When I do it is very slight and it is 21' F here in Alaska..

svtkidd23 · November 12, 2013

My truck gets in v4 pulling out driveway tilll 45mph..And it's rough

Stex · November 12, 2013

See the Range, forum vendor, or tune out afm..I would try the range before a tune.

fondupot · November 12, 2013

My V4/V8 transition is almost seamless. If I listen closely I can hear it, but as far as any jerkiness or clunkiness there is none.

Yesterday it got pretty cold and it took a little while for the truck to start using V4 mode, but once it warmed up it was fine. No complaints here.

And to the OP. Colder weather means winter blend gasoline at gas stations. Winter blend gas is notorious for getting worse gas mileage because of the extra chemicals added to the gasoline to offset the cold temperatures of being stored underground in sub-freezing temperatures. This is NORMAL.

fyrman · November 12, 2013

I will say the transmission shifting and the AFM from V-4 to V-8 is seamless.

Silver space ship · November 13, 2013

My truck is all over the place with the AFM. Today it was 38* in the grage when I pulled it out to go to work but only 7* outside, when I pulled out on the hwy as soon as I got to speed it went into v4, I looked at my engine temp and I was a hair over 160* few seconds latter went back into v8 for the next 11 miles. It seems to me like its struggles between engine temp, outside temp and parking it in a heated garage is confusing it a bit. I would think it would be all off of engine temp.

Tonight on the way home it was 28* and truck sat outside all day and it was going back and forth form v4 and v8 like normal and my engine temp wasn't even close to 210 yet.

joshw1303 · November 13, 2013

My truck is all over the place with the AFM. Today it was 38* in the grage when I pulled it out to go to work but only 7* outside, when I pulled out on the hwy as soon as I got to speed it went into v4, I looked at my engine temp and I was a hair over 160* few seconds latter went back into v8 for the next 11 miles. It seems to me like its struggles between engine temp, outside temp and parking it in a heated garage is confusing it a bit. I would think it would be all off of engine temp.

Tonight on the way home it was 28* and truck sat outside all day and it was going back and forth form v4 and v8 like normal and my engine temp wasn't even close to 210 yet.

These motors don't wait for temp. It could be minus 20 out and you just started to drive and it could go into v4. Not good for motor long term.

rocnrol · November 13, 2013

I have noticed that the AFM in my truck seems to stay off longer in the colder weather too. It's been around -10 (14*) here for awhile and the pattern of its operations seems to follow the weather. I have also noticed that the fuel milage has gotten worse in the colder weather, which I attributeted to the computer throwing more fuel at the engine, I had forgotten about the winter blend fuel

Silver space ship · November 13, 2013

GMMan, I would agree but the last two mornings it's been 12* and 7* and other then a a few seconds this morning my truck stayed in v8 until it hit 210* but on the way home after work and the temps are in the mid 20's then it seem to go into v4 just like it would on a summer day. I'm just trying to figure out why its so inconsistent.

svtkidd23 · November 13, 2013

Mine is in v4 at 30-40mph while some cold and it is rough feeling tap the gas to v8....Shes smooth

waumo1 · November 14, 2013

1.5 to 2 MPG loss in all my vehicles as soon as the stations switch to winter blend.

TJay74 · November 14, 2013

If any of the specs from the prev gen motor carried over, the engine has to be over 97° and has to been running for at least 30 seconds before DOD can go active.