cablebandit

iTrader: (37)

porting a MAF reports less load to the pcm which causes you to run a little leaner AND makes the pcm think "less load...dont need so much line pressure"...that aint good. The stock pcm calibration is not what I want interpreting my mods for line pressure. Vacuum mod does this...foot to the floor...full line pressure..it dont care if you even have a maf. Take my car..half throttle and I can have 2-3psi of boost....I dont want the pcm to think "half load so half line pressure".....the vacuum mod see boost or no vacuum and applies full line pressure.

Automatics

The vacuum modulator can also increase the main line pressure in manual 3 from about 170-190 psi., to about 220-235 psi at WOT. This is a "big " advantage when addressing the 3-4 clutch life expectancy. It also makes a dramatic difference in 4-3 or 3-2 downshifts, it happens instantly, instead of the the usual 1.25 - 2.0 seconds delay. The vacuum modulator is using "real world" readings, instead of "pcm calculated load" quoted earlier. I am sure that one day the PCM will be able to do what we want in all circumstances, but that time is still a ways off, from what I can see. Till then, I will use the vacuum modulator in all of my High Performance units.

sleeperstyle

iTrader: (4)

is vaccum modulation a good or bad idea in an otherwise stock 4l60e w/ a shift kit?

blkZ28spt

Good. The same things apply whether or not the transmission has been upgraded.

real82it

Dmoney,

I just bought a vacuum modulator kit for my 4L60E. The installation was more than I expected looking at the instructions. Did you actually have to drill your valve body?? What kit did you use? Can you give me an overview of what you had to do in order to install?

Dmoney

iTrader: (22)

It's not as tough as it looks. I used the trans go from Pro-Built. If you can do it on a lift do it. I did it from under the car on lifts. Yes, you have to drill, but was fairly easy as there is an actual X on the valve body to show you where to drill. Start with a small drill bit and work your way up to the required size cuz your never gonna finish drilling with that big drill bit. Tap and screw in the fitting. Don't forget to tap the hole. I had to buy the drill bit and the tap. There is a yellow connector that plugs into the EPC solenoid, you can't miss it. You have to remove the accumulator as per instructions(4 bolts) to get the EPC out. Unplug the connector and the EPC should come out. You will need to split the connector down the middle into two seperate connectors so that it will fit the black relay or whatever it's called . Put the modulator together as instructed and install. Then the line is pretty easy. Don't cut to much from the vacuum line. If you get stuck just let me know. Instructions are somewhat usefull, but you pretty much have to figure it out yourself.