Removing Secondary Vacuum System questions.

[DScott600]

I have a chip from the ZR1 Specialist for my 91 and decided to get the option for the chip that eliminates the need for the secondary vacuum system. According to Marc I can remove all of the secondary vacuum lines and just leave the sensor under the ECM exposed to the atmosphere. My question is after removing the vacuum lines, the solenoid and canister what should I do with the line that runs into the drivers side of the plenum? Does this line now need to be plugged? Also is there a better way to tie the secondaries open besides just using wire ties? Or is there a good way to remove the throttle plates with the injector housings still in without dropping anything into the engine? Later I am planning on getting the top end ported and removing the shafts and all.

[Paul Workman]

Originally Posted by DScott600

I have a chip from the ZR1 Specialist for my 91 and decided to get the option for the chip that eliminates the need for the secondary vacuum system. According to Marc I can remove all of the secondary vacuum lines and just leave the sensor under the ECM exposed to the atmosphere. My question is after removing the vacuum lines, the solenoid and canister what should I do with the line that runs into the drivers side of the plenum? Does this line now need to be plugged?

Yes, it has to be plugged.

Originally Posted by DScott600

Also is there a better way to tie the secondaries open besides just using wire ties? Or is there a good way to remove the throttle plates with the injector housings still in without dropping anything into the engine? Later I am planning on getting the top end ported and removing the shafts and all.

Dom tied his throttle plates open w/ a tie-wrap.

As for removing the plates, you might be able to stuff some foam into the IH to catch anything that might be dropped. In my case, I used one of those telescoping magnet thingies and placed the magnet on top of the plate next to the screws. that worked well - gave piece of mind.

You'll like running w/o the secondary hardware. I promise!

Parts not used seldom fail, and they don't cost much!





P.

[DScott600]

Thank you for the info, I will plug it and tie the secondaries open. I might attempt to remove the plates using the magnet trick as well. I should have it all back together by Wednesday night if I get my plenum gaskets I ordered Saturday by then. I'll report how she does when I do.

[Locobob]

I think you'll have a tough time accessing the screws on the secondary throttle plates with the injector housings still on, save yourself the grief and just pull em.

[XfireZ51]

Originally Posted by Locobob

I think you'll have a tough time accessing the screws on the secondary throttle plates with the injector housings still on, save yourself the grief and just pull em.

BTW, I removed the throttleplates themselves and then tie wrapped the throttle mechanism open so the shafts presented the narrowest side to air flow.

[John Boothby]

Does tying open or removing the secondary throttle plates effect the emissions? I remember when I first got my car a few years ago the first time I had it smogged I forgot and left the power key on full power. The car failed the test with high HC. I went home depressed. I thought about this overnight, and the next day I went back with the key turned off and it passed with no problem. It has never failed since. Someone said this should not matter, however it did in my case. The car runs great and always has.

[DScott600]

Well I already have the plenum gaskets ordered from Jerry and I would like to get it back together by Wednesday if they come in. I don't want to have to order the injector housing gaskets and wait on them. If I went that far I would probably replace the breather gasket and loctite the bolts so they want back out (even though it doesn't leak after I pulled the plenum the first time and tightened the bolts.) I plan on having the money to go ahead and do the full top end porting and powder coating with stainless steel bolts and all early to mid next year, if all goes well. So I suppose I will just tie the linkage open for now and then take the plates out when I pull it all apart to do the porting along with a better clean up and replacing the breather gasket too. For now I'll put the 30 or so dollars I would have to spend on injector housings gaskets toward my c5 brake upgrade. Does this sound reasonable to you guys?

[DScott600]

Oh and in response to John Boothby I'm sure that running without the secondaries would effect emissions. Marc told me that the main reason GM did the secondaries is for emissions. But I'm sure the experts may chime in on this one.

[John Boothby]

I understood that the main reason for the secondaries was for fuel consumption so that a buyer would not have to pay the gas guzzler tax.

[Pete]

Here is the answer to emissions 2 chips.

One for emissions,one for performance.

Marc should know what to do.

Pete