Hesitation when secondaries engage? - ZR-1 Net Registry Forums

rudolph schenker · 07-11-2010

I finished my first plenum pull a few months ago. I had Marc Haibeck refinish my plenum, cam covers and injector housings (they look great now). I also replaced my injectors and all the vacuum fittings for the secondaries. I did not replace the secondary cans?

I get some hesitation now when the secondaries engage ( I had some hesitation before) but it is more pronounced now. I only get this with the engine key turned to "full".

Where should I start looking to fix this? I would like to keep things stock. I know some have wired the secondaries open, I don't think I want to do this.

Any opinions or advice appreciated!

rhipsher · 07-11-2010

You have a secondary vacumm leak. Take a paper clip or bobby pin go to your diagnostics port below your steering wheel. Stick one end in terminal A and one end in terminal G. A is the top far right one and G is the far bottom left side at least on a 90 it is. Turn your key on but don't start the car. Look at your speedo and it will flash C12. That means that there is communication from the ECM. Then next if there are any codes stored they will display. If it's a vacumm leak it will show H61 for secondary vacumm port failure. Then go get a vacumm pump and start checking. There is a great right up on this on the corvetteactioncenter.com

rudolph schenker · 07-12-2010

Quote:

Originally Posted by Dynomite

I think this is the web site rhipsher refers to http://www.corvetteactioncenter.com/...diagnosis.html

Thanks for the replies. I will check the link this weekend, when I get some time. I also want to thank Demps for taking the time to call me and explain things! The ZR-1 net is a place like no other!

Belsy · 07-12-2010

Make sure to triple check the secondary solenoid!!! Vac to & from this can be confusing as the solenoid blocks vac when not energized and pump will keep running when it should not. Follow the setup from Marc Haibeck
There are substitute solenoids available to do the same job with modifications if nec.!! Codes will help.

rudolph schenker · 09-11-2010

Ok, I finally got around to solving this little problem. I followed Marc Haibeck's instructions (they were very helpful). I pulled the plenum ( was not nearly as hard as the first time) and checked all my vacuum lines. I then checked the actuators, they seemed ok but I replaced them anyway. I was told from previous pics that they were installed backwards, so I rotated the new ones 180. I have to admit I saw very little difference on the actuator mechanisms regardless of how they were mounted. I found a small leak around the secondary solenoid and fixed it. I put everything carefully back together and....................

No hesitation at all!!!!!!!!

I must thank this forum for all their help and knowledge, especially Demps for his phone call and expertise!!

07-11-2010	#1
rudolph schenker Join Date: Jun 2009 Location: utah Posts: 128	Hesitation when secondaries engage? I finished my first plenum pull a few months ago. I had Marc Haibeck refinish my plenum, cam covers and injector housings (they look great now). I also replaced my injectors and all the vacuum fittings for the secondaries. I did not replace the secondary cans? I get some hesitation now when the secondaries engage ( I had some hesitation before) but it is more pronounced now. I only get this with the engine key turned to "full". Where should I start looking to fix this? I would like to keep things stock. I know some have wired the secondaries open, I don't think I want to do this. Any opinions or advice appreciated! __________________ 1994 ZR-1 Admiral blue/beige #67

07-11-2010	#2
rhipsher Join Date: Aug 2008 Location: Houston 90 Red ZR-1 Posts: 2,320	Re: Hesitation when secondaries engage? You have a secondary vacumm leak. Take a paper clip or bobby pin go to your diagnostics port below your steering wheel. Stick one end in terminal A and one end in terminal G. A is the top far right one and G is the far bottom left side at least on a 90 it is. Turn your key on but don't start the car. Look at your speedo and it will flash C12. That means that there is communication from the ECM. Then next if there are any codes stored they will display. If it's a vacumm leak it will show H61 for secondary vacumm port failure. Then go get a vacumm pump and start checking. There is a great right up on this on the corvetteactioncenter.com Last edited by rhipsher; 07-11-2010 at 08:43 PM.

07-12-2010	#4
Belsy Join Date: Nov 2006 Location: DeBary , Fl. Posts: 119	Re: Hesitation when secondaries engage? Make sure to triple check the secondary solenoid!!! Vac to & from this can be confusing as the solenoid blocks vac when *not* energized and pump will keep running when it should not. Follow the setup from Marc Haibeck There are substitute solenoids available to do the same job with modifications if nec.!! Codes will help. __________________ Gene in Fl. :handshak: ______________ 95 ZR-1 #399 Dunn heads X-pipe w/3" misc. mods

09-11-2010	#5
rudolph schenker Join Date: Jun 2009 Location: utah Posts: 128	Re: Hesitation when secondaries engage? Ok, I finally got around to solving this little problem. I followed Marc Haibeck's instructions (they were very helpful). I pulled the plenum ( was not nearly as hard as the first time) and checked all my vacuum lines. I then checked the actuators, they seemed ok but I replaced them anyway. I was told from previous pics that they were installed backwards, so I rotated the new ones 180. I have to admit I saw very little difference on the actuator mechanisms regardless of how they were mounted. I found a small leak around the secondary solenoid and fixed it. I put everything carefully back together and.................... No hesitation at all!!!!!!!! I must thank this forum for all their help and knowledge, especially Demps for his phone call and expertise!! __________________ 1994 ZR-1 Admiral blue/beige #67