My trans broke last week, third and fourth gear went out.
I had the HPerf. replacement parts sent to the shop and I stopped by today to check them out.

The round connector that is on the passenger side goes to all of the selonoids within the trans. One of those selonoids is called the pressure control seloniod. It varies the line pressure which produces firm or soft shifts. I was always wondering how come ls1edit would never vary the shifts when I was modifying the table. I found out!!!!
The 4L60E's are fully electronic. Including the pressure seloniod. But, mine had a vacuum modulator like the 700R4's. Hmmmm. The connector that was supposed to connect to the pressure control seloniod had a resistor welded across the terminals. Which tells the computer to apply full pressure to the line. Which doesn't matter because the vacuum part was in it's place.
So i have a 4L60E with a vacuum controlled modulator instead of an electronic selonoid.
I have a spare 4L60E that came out of the Tahoe i'm going to remove the parts i need and pull that damn vacuum device out. Now ls1edit will make a difference.
I always wondered why I was the only one with a vacuum line going to the trans, i guess i was just used to the old days of TH350 and never really thought about it.

later,

allen

 

many, maybe all of the tranz shops that build these things for high hp goto vacume modulation, i am not sure of all the reasons but one i know of for sure is to keep you from messing with the presures.

when my flp tranny went bad a few people said right off the bat that it must have been my tuning that caused it to go bad. if you mess with your maf it effects your line presures. well with the vacume modulation there is no way a funky tune can hurt your tranny.

i would keep it, just hook up a vacume line.

 

I may re think my build then. I had the vacuum hooked up to the back of the intake, i may just try and adjust the modulator. i'll post and try and get more information on it.

most people on ls1edit list say the maf adjustment or ported maf or descreened maf haf nothing to do with the line pressure. I haven't heard good enough reasons from either side to base my opinion.

anybody?


thanks,

allen

 

if you use a MAFT or ls1 edit to play with your maf charts i have been told it will effect your line presures.

if you had a vacume line to your intake then it was probably working, you can try pulling the line and see if it gets any firmer

my truck is VERY firm, BANG firm, i unhooked the vacume line and it was even firmer <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> , i am used to it but it shifts so firm that in the snow if i am riding the brake at all it sets off the antilocks, i may have to unplug them.