ZR-1 Net Registry Forums  

Go Back   ZR-1 Net Registry Forums > C4 ZR-1 > C4 ZR-1 Technical Postings

Reply
 
Thread Tools Display Modes
Old 08-25-2013   #1
KJL
 
Join Date: Mar 2013
Location: Roswell, GA
Posts: 232
Default How to vacuum test secondary throttle actuator system

I have the plenum removed and thought it would be a good time to check the secondary vacuum actuators. I have a hand vacuum pump I use to check things out on my 72. With plenum removed, where should pump be connected and what lines should be plugged? There are lines to a vacuum pump, sensor (mounted under plenum) and a line that goes to the plenum and connects to the solenoid (not sure what this is for other than solenoid activation?).

Thanks!!
__________________
1995 ZR1 #159
Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp
1992 ZR1 #280
Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp
1996 Collectors LT4 (Stock)
1972 Convertible 434 Small Block
572 rwhp
KJL is offline   Reply With Quote
Old 08-25-2013   #2
XfireZ51
 
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,656
Default Re: How to vacuum test secondary throttle actuator system

I would start by checking at the Diff MAP Sensor under the ECM. See if the line connecting to it holds vacuum.
__________________
[SIGPIC][/SIGPIC]Former Membership Chairman
Former ZR-1 Registry - BOD
1972 Corvette 4speed base Coupe SOLD long time ago
1984 Corvette Z-51/4+3 SOLD
1992 Corvette ZR-1 Aqua/Gray #474 SOLD
1992 Corvette ZR-1 Black Rose/Cognac #458
2014 Honda VFR Interceptor DX
XfireZ51 is offline   Reply With Quote
Old 08-25-2013   #3
scottfab
 
scottfab's Avatar
 
Join Date: Jan 2009
Location: Portland Oregon metro area (Washington side)
Posts: 3,207
Default Re: How to vacuum test secondary throttle actuator system

Quote:
Originally Posted by KJL View Post
I have the plenum removed and thought it would be a good time to check the secondary vacuum actuators. I have a hand vacuum pump I use to check things out on my 72. With plenum removed, where should pump be connected and what lines should be plugged? There are lines to a vacuum pump, sensor (mounted under plenum) and a line that goes to the plenum and connects to the solenoid (not sure what this is for other than solenoid activation?).

Thanks!!
I'd go straight to the hose on each actuator. Test one at a time for smooth non sticking action and no leak down. If you have problems here there's no real advantage to moving to other tests.
__________________
Scott


Vett owner since 1979._It's about the car and the people

Last edited by scottfab; 08-26-2013 at 12:02 AM.
scottfab is offline   Reply With Quote
Old 08-25-2013   #4
KJL
 
Join Date: Mar 2013
Location: Roswell, GA
Posts: 232
Default Re: How to vacuum test secondary throttle actuator system

I checked at the map sensor and it did not hold vacuum. Not sure if all lines need to be connected and solenoid to be energized for that to work.
__________________
1995 ZR1 #159
Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp
1992 ZR1 #280
Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp
1996 Collectors LT4 (Stock)
1972 Convertible 434 Small Block
572 rwhp
KJL is offline   Reply With Quote
Old 08-28-2013   #5
RICHARD TILL
 
Join Date: Aug 2005
Location: Iuka, Mississippi 38852
Posts: 756
Default Re: How to vacuum test secondary throttle actuator system

Did you try to pull a vacuum on the sensor itself or on the line that attaches to the sensor? I have my plenum off now for an injector change and secondary repair. I needed alternator repair, injectors, one coil, vacuum pump and a sec. port throttle solenoid. Maybe it`ll roar back to life next week.
RICHARD TILL is offline   Reply With Quote
Old 08-28-2013   #6
KJL
 
Join Date: Mar 2013
Location: Roswell, GA
Posts: 232
Default Re: How to vacuum test secondary throttle actuator system

Good luck-
I suspect to test it correctly, I will need to rig up some tubing to connect to all of the vacuum sources and electronically activate the solenoid in order to see if the system functions properly. I may try to post this question in the Corvette Forum to see if I get any bites there as well.
__________________
1995 ZR1 #159
Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp
1992 ZR1 #280
Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp
1996 Collectors LT4 (Stock)
1972 Convertible 434 Small Block
572 rwhp
KJL is offline   Reply With Quote
Old 08-28-2013   #7
RICHARD TILL
 
Join Date: Aug 2005
Location: Iuka, Mississippi 38852
Posts: 756
Default Re: How to vacuum test secondary throttle actuator system

i checked my actuators by hooking a 6 foot vacuum hose to the vacuum pump on the car. i hooked an alternate power source to the pump and then pinched the line off until i could get it hooked to each of them. the pump ran for a second and then stopped. thats when i waited about 15 minutes to see if the pump restarted. it didn`t so i assumed i didn`t have a leakdown. there are two vacuum lines hooked to the secondary port throttle solenoid. they both unplug together. i took a small piece of copper tubing and stuck it in the hose from the pump. i stuck that line into the vacuum line going to the actuators. another 15 minute test and it passed. no leakdown and worked smoothly. my problem was vacuum leaking thru the solenoid. it can be tested by applying 5-6 volts.
RICHARD TILL is offline   Reply With Quote
Old 08-29-2013   #8
scottfab
 
scottfab's Avatar
 
Join Date: Jan 2009
Location: Portland Oregon metro area (Washington side)
Posts: 3,207
Default Re: How to vacuum test secondary throttle actuator system

Quote:
Originally Posted by KJL View Post
Good luck-
I suspect to test it correctly, I will need to rig up some tubing to connect to all of the vacuum sources and electronically activate the solenoid in order to see if the system functions properly. I may try to post this question in the Corvette Forum to see if I get any bites there as well.
I'd go straight to the hose on each actuator. Test one at a time for smooth non sticking action and no leak down. If you have problems here there's no real advantage to moving to other tests.
__________________
Scott


Vett owner since 1979._It's about the car and the people
scottfab is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:46 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ZR-1 Net Registry 2020