[limskii]

I have the CTS for my 2010 Ford F150 Screw FX4 with the 5.4L and custom PHP tunes. Is there a ride in time (driving some miles) required for the full benefits of a custom tune to be realised when changing from one tune to another ? The reason I ask is because a couple weekends ago, I switched to my custom 87 tow tunes to pull my enclosed trailer to the cottage from the 91 performance tune that I had been running with 91 gas. At the cottage, I wanted to show my neighbour how well the truck responds and accellerates with the CTS programmer as he owns a stock 2011 Screw XLT with the new 5.0L. I switched back to the custom 91 performance tune and warmed up the truck and brought him out on the hwy for a drive but the truck seemed like stock again. I even did 2, 1/4 mile test runs and had one at 16.8 @ 82mph and the other at 16.6 @ 84mph. When I first got my custom tunes, I did some stock 1/4 mile tests with a best of 16.8 @ 82mph and then tested the 1/4 mile with the custom 91 performance tune and had a best of 15.6 @ 94mph which my programmer still has as a saved record. Anyways, my neighbour liked the CTS and was impressed with the accelleration of the truck but I told him it usually feels alot quicker than that and was confused at why it felt and ran slower. We figured it may be the outside temps as it was 25C and humid that day whereas when I had originally done my tests it was about 16C and drier out. I am now running the 91 performance again for the last two weeks and it feels as quick and responsive as it felt before that weekend at the cottage. Any insight appreciated.

[ticopowell]

My main thoughts... Altitude. How high do you live and how high is the cottage? If you go from relatively sea level to anything over 2-3k feet you will feel a significant difference, and the difference only increases as you go higher... less air up there equals less power potential. The temperature will also have an impact because of the density factor, as it heats up, it gets less dense, meaning less oxygen to burn.
Let me know if that makes sense for your situation.

[JackandJanet]

The difference between 16C and 25C is rather significant, as would be the effect of high humidity on top of the higher temperature. Both contribute to a loss of air density which reduces the absolute compression you have in the engine and reduces the fuel you are introducing into the cylinders too.

I think ticopowell was absolutely correct in his analysis. If you are also at a higher elevation, it compounds the situation.

As far as I know, there is no "ride in" time for a tune.

- Jack

[limskii]

I think maybe the temperature and humidity could be the culprit then as our cottage is only 1/2 hour away from home and our altitude here is around 800' above sea level, no mountains or big altitude changes here. Thanks for the replies.

[Longshot270]

I'm with Jack on the temps. 9˚C is a noticeable swing. I've never seen results for humidity but it seams logical that it would not be helping you out.

[03gixxer1000]

How heavy was your friend?

Sent from my Droid Thunderbolt.

[ticopowell]

Originally Posted by 03gixxer1000

How heavy was your friend?

Sent from my Droid Thunderbolt.

[03gixxer1000]

you may laugh, but passenger weight can really affect acceleration and handling. You can really feel the affects on a motorcycle. Not only that but a full tank of gas weighs alot more than a quarter tank. Could have been weight defferential coupled with environmentals.

[Longshot270]

Originally Posted by 03gixxer1000

you may laugh, but passenger weight can really affect acceleration and handling. You can really feel the affects on a motorcycle. Not only that but a full tank of gas weighs alot more than a quarter tank. Could have been weight defferential coupled with environmentals.

+1, I've noticed it as well when I had passengers. Mostly when I would take friends drifting out on gravel roads. Having a slight shift/addition of weight needed to be accounted for to make my apex and exit points precisely without over or undershooting.

But you also have the mentality that you are showing off your truck, which is a product of your personal tastes and in essence, yourself. In this case you always wish it was just a tad faster.

[ticopowell]

Oh I know how much weight affects things... I got a trailer... and a Bike! , and any truck I have driven has been affected quite a bit with only a few extra people.