Re: Did you eliminate your Secondary Throttle Vacuum System?
 

One of the first things I did with my ZR-1 was to disable the secondaries, using chip mods by Haibeck. I was happy with the results. Simplified the system and the car ran well.

About a year later DIY Tune (aka Megasquirt) asked if they could use my car to try and finish up their MS3-Pro ECU for the LT-5. I said sure!

When they found out my secondaries were removed, they asked me if I could add them back in. I did, lent them my car, got it back a month later and it ran great. It was noticeably stronger. I'm sure that is because they had the luxury of running many iterations of tune and were able to reach an optimum tune.

They said they found that working secondaries helped the engine run better. I don't remember the details about why they believed that. My memory fails me. Perhaps it was the transition stage (a guess).

My hunch is, the computing power available today (compared to the late 1980's) allows them more control over the injectors and butterflies.

I'm certainly not knocking the removal of secondaries. I'm just sharing this experience to the thread.

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

Did MS ever market this system for the LT5? Is it still in your car?
H
:cheers:

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

I think your perception of better performance has more to do w a custom tune
than any other factor.

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

I'm not sure. I haven't seen it mentioned on their web site. You might need to call them. Yes, it's still in my car. Engine runs great.
No doubt. I'm sure someone like Marc could do the same with enough time. The MS3-Pro is a lot easier and faster than altering the GM ECU, especially if the chip has to be mailed to someone to make a change.

BTW, it's not perception. :-)

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

Question: when you eliminate the secondaries does the engine then have less HP ?


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Re: Did you eliminate your Secondary Throttle Vacuum System?
 

With Secondaries Eliminated and dependent on CHIP and Tuning.....you have More HP over a much wider range of engine RPM and Throttle Position.

This Marc Haibeck Link explains when the secondaries are functional as dependent on engine RPM and Throttle Position when in FULL POWER Mode :thumbsup:

Marc Haibeck Discussion on Secondary Operation

It should be noted that the 1990 ZR-1, 1991-1992 ZR-1 and 1993-1995 ZR-1 have different Secondary Operational limits in regard to RPM and Throttle Position. It should also be noted this only applies when the Full Power Switch is on FULL POWER.

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

"Definition of perception for English Language Learners. : the way you think about or understand someone or something. : the ability to understand or notice something easily. : the way that you notice or understand something using one of your senses."

So perception can be and is reality. I was not implying that you were "imagining" a better running motor.

I don't think its any more difficult in modifying the tune using the OEM ECM.
There's many more parameters that an OEM needs to address and configure due to emissions, driveabiity, and fuel consumption considerations. Understanding how to use them actually gives you greater control over the tune. Not having used the software for the MS3, I can't comment further on its usability, but I can say that it is not necessary to ship your prom anywhere in order to make changes.
There's technology available, pretty inexpensively, that makes tuning on a remote basis a possibility.

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

I removed them in 2012 and never looked back. One of the butterfly blades broke ingesting the blade and butterfly screw in the top of piston number #2 wedging it open and bending the intake and exhaust valves... I would not of believed that happening or could happen except this was the second time this had happened as last time one of the blades lost the screw on the other side. I suggest if you are in there. Pull em. the secondary system is prone to vacuum failures and leaks and who drives without the car in full power anyway?

The secondary system has two benefits only. Lower emissions and better fuel economy. What you gain is about 1 second response in throttle time, a valley area free of the secondary system with multiple points of failure and the potential of what happened to me in #2014 NOT happening to you. Go boldly.

Debate over.

GC

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

:sign10:

Well...well.....hmmmm....
I like that feature of Full Power with the switch of a key. That is attractive to guys who like the feature of kicking in another set of injectors and doubling the intake porting with the flip of a key. Very Unique and I just like it.

Once you fix vacuum leaks the vacuum leaks do not seem to come back :thumbsup:

Now Debate over :D

Oh.....yes.....I dropped one of those throttle cable bracket screws into the Injector Housing and had to install a new sleeve and a new piston in one cylinder.

Re: Did you eliminate your Secondary Throttle Vacuum System?
 

Hmmm, eliminates maintenance issues, removes potential catastrophic failures, and car runs better? Starting to sound like a really good idea.

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