I installed the Edge Evolution CS on my 03 2wd SuperCrew 5.4 last week. Everything is great after tweaking the transmission points and firmness in Towing mode, except for an occasional problem:

If I'm cruising in 4th gear, with the TC locked up, and I let off the gas, it will unlock the TC then the exhaust gets louder (instead of just about silent, like it used to) and the truck decelerates harder than usual. I cleaned the throttle body and MAF yesterday, but didn't help.

Also, I may have a vacuum leak somewhere because my AC compressor kicks on in Panel & Floor mode. Could these two problems possibly be linked to a vacuum leak?

Any ideas?

 

You probably set it to down shift into third at a certain RPM amount in 4th

 

No, it stays in 4th after the TC unlocks. And as soon as I give it some gas, TC locks up again, so that all seems to work fine.

I'm thinking its an engine problem more so than a tranny problem.

 

Also, does anyone know if the vacuum line that goes through the firewall is easily accessible from the inside? All my vacuum lines are good under the hood. I tried a little test, but I'm not sure that its not doing what it should or not.. I unplugged the line at the firewall and sucked on the line and could definitely feel air was being pulled through. This was with the AC switch in the "Off" position.

I guess I'll probably need to bypass that line temporarily to see if it fixes my problems, but I'd rather not splice into the line at the harness on the panel.

If the vacuum line going through the firewall is just for the AC, the. I'll just plug it under the hood to see if that fixes it. Does anybody know what all that vacuum line goes to inside the cab?

 

What transmission settings did you change, and why?

Did it do it before you messed with the custom settings?

Towing mode will use the engine more to help decelerate instead of freewheeling when you let off of the gas. The settings you changed may have magnified this.

 

I changed the shift points up a few MPH so the RPM didn't drop so much. But I remembered that it did do it a few times (very few) before I got the programmer. But now it does it more, about 1 or 2 times a day. So I'm thinking it was an existing issue, but something with the tuning makes it happen more..

 

I've been looking at vacuum diagrams and it appears that the vacuum line that goes through the firewall is just going to the AC control panel. So I'll be plugging that to see what happens with the transmission.. But it also looks like the AC compressor is just controlled electronically, so I'm thinking I'll need a new selector switch, I'll check it with a volt meter tomorrow.

But I tried a little experiment on the way home: After the truck started doing the decelerating thing, I got back on the gas and turned the **** to all the positions to release the vacuum or whatever it does and it stopped doing it the rest of the way home. So I'm still thinking it's a vacuum problem causing that.

 

Not trying to hijack man, but if you were to leave it like that, would it hurt the tranny? Mine does that, but i dont have a programmer or anything....

 

I wouldn't think so.. Its more of an annoyance for me. But I played with the AC selector again this morning and got it to stop again, so I'm 99.9% sure its vacuum related. I'll let ya know what it is when I find it.

 

The trans shouldn't be affected by vacumn at all, our transmissions are electronically controlled. Decel engine braking is a great feature and won't hurt anything, many 3/4-1 ton trucks with towing packages do this from the factory. It may also be a torque converter issue with the lockup solenoid/PCM