Automatic Transmission 2-Speed thru 10-Speed GM Autos | Converters | Shift Kits
Sponsored by:
Sponsored by:

Does the PCM control line pressure...

Thread Tools
 
Search this Thread
 
Old Dec 23, 2005 | 09:13 AM
  #1  
CoonToot's Avatar
Thread Starter
TECH Regular
 
Joined: Dec 2002
Posts: 488
Likes: 0
From: Pensacola, FL
Default Does the PCM control line pressure...

...in any way OTHER than through the EPC solenoid? My local tranny shop just installed a TransGo vac mod kit, yet the tranny is slipping on every upshift. My feeling is that the guy may not have installed the vac mod kit correctly as slipping in all gears probably points to low line pressure across the board. I just need to know if the EPC solenoid, which is bypassed/pacified with the vac mod kit, is the only point of line pressure control via the PCM. In other words, if the EPC is removed from the equation, is there any other manner by which the PCM could control/effect line pressure?
Reply
Old Dec 23, 2005 | 05:34 PM
  #2  
jxaxsxoxn's Avatar
Banned
iTrader: (2)
 
Joined: Jun 2004
Posts: 873
Likes: 2
From: Arizona
Default

No.
The only other pcm controlled parts in the trans are the three shift solenoids and the tcc solenoid.

I have the kit waiting for me to install it and when I do I am going to install a pressure gauge before I even start the car, then I will apply and take away vacuum to verify line pressure response.

IMO I wouldn't drive the car until it's fixed, it may already be too late.
Reply
Old Dec 23, 2005 | 05:53 PM
  #3  
WILWAXU's Avatar
TECH Senior Member
20 Year Member
iTrader: (6)
 
Joined: Nov 2001
Posts: 14,378
Likes: 1
From: League City, TX
Default

Hmm.. I'm certainly no expert, but isn't there is a solenoid that controls line pressure also? It's the one we remove when we add a vacuum modulator kit.
Reply
Old Dec 23, 2005 | 06:00 PM
  #4  
jxaxsxoxn's Avatar
Banned
iTrader: (2)
 
Joined: Jun 2004
Posts: 873
Likes: 2
From: Arizona
Default

Originally Posted by WILWAXU
Hmm.. I'm certainly no expert, but isn't there is a solenoid that controls line pressure also? It's the one we remove when we add a vacuum modulator kit.
You need to read the top post again.
Reply
Old Dec 24, 2005 | 11:22 AM
  #5  
jxaxsxoxn's Avatar
Banned
iTrader: (2)
 
Joined: Jun 2004
Posts: 873
Likes: 2
From: Arizona
Default

Anyone else?
Reply
Old Dec 24, 2005 | 11:38 AM
  #6  
kpowr82's Avatar
TECH Resident
iTrader: (9)
 
Joined: Jan 2004
Posts: 967
Likes: 0
From: Rochester, MI
Default

According to Dave at Rock-On, there are several factors that determine the applied line pressure of a transmission. Some of them include the MAF, MAP, IAT, etc. The vac mod kit eliminates all of the guesswork, though the PCM still thinks it's controlling line rise and such.

If you're slipping through all the gears like you say, then the vac mod kit was not setup correctly. There have been many posts here recently about whether or not the vac mod kit is plug and play or an easy install. I'd say your trans shop may not have had that much experience with vac mod conversions.
Reply
Old Dec 24, 2005 | 04:33 PM
  #7  
CoonToot's Avatar
Thread Starter
TECH Regular
 
Joined: Dec 2002
Posts: 488
Likes: 0
From: Pensacola, FL
Default

Originally Posted by kpowr82
If you're slipping through all the gears like you say, then the vac mod kit was not setup correctly. There have been many posts here recently about whether or not the vac mod kit is plug and play or an easy install. I'd say your trans shop may not have had that much experience with vac mod conversions.
I think that is where the problem lies...in the install. The tranny tech has never installed one before mine. I have some things to discuss with him next week. Thanks for the feedback.
Reply
Old Dec 24, 2005 | 04:34 PM
  #8  
WILWAXU's Avatar
TECH Senior Member
20 Year Member
iTrader: (6)
 
Joined: Nov 2001
Posts: 14,378
Likes: 1
From: League City, TX
Default

Originally Posted by jxaxsxoxn
You need to read the top post again.
Dooh, your right
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

 Brett Foote
story-1

Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

 Pouria Savadkouei
story-2

Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

 Verdad Gallardo
story-3

7 Most Reliable High-Performance Engines GM Has Ever Built

 Verdad Gallardo
story-4

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-5

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-6

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-7

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-8

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-9

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo




All times are GMT -5. The time now is 07:40 PM.

story-0
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

Don't get dad new socks or a grill brush this year.

By Brett Foote | 2026-06-09 14:55:56


VIEW MORE
story-1
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-2
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-3
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-4
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-5
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-6
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-7
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-8
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-9
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE