secondary issue

[spork2367]

Pulled my intake for a starter issue and was doing a quick vacuum check and found the passenger side secondaries sticking. Upon further investigation I found this...The bent butterflies don't appear to have caused the sticking issue, as it was still sticking after their removal. What else would cause this?

[Ccmano]

The vacuum actuators certainly don't have enough force for something like that. I wonder if somewhere along the line there was a backfire that caused it. Are they all like that?
H
:cheers:

[Paul Workman]

The vacuum actuators certainly don't have enough force for something like that. I wonder if somewhere along the line there was a backfire that caused it. Are they all like that?
H
:cheers:

Backfire...was my guess too.:icon_scra

[A26B]

Pulled my intake for a starter issue and was doing a quick vacuum check and found the passenger side secondaries sticking. Upon further investigation I found this...The bent butterflies don't appear to have caused the sticking issue, as it was still sticking after their removal. What else would cause this?

Bent shafts can cause sticking. Did you remove them too?

[Ccmano]

Time to just omit the secondaries altogether. :thumbsup: I have a set of butterflies if you need them.
H
:cheers:

[spork2367]

Backfire...was my guess too.:icon_scra

That was my only guess, but I find it hard to believe. This was just on the back two cylinders on the passenger side.

Bent shafts can cause sticking. Did you remove them too?

After I pulled these two butterflies, everything freed up. I'm going to straighten them and refit them.

[Jagdpanzer]

A real mystery. With the adjacent intake valve being open or closed more or less at the same time hard to imagine that much force being generated that would bend a secondary butterfly like that. Has anyone else every experienced this?


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[Jagdpanzer]

I have a few new take out butterflies for free if you need them.


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[spork2367]

I have a few new take out butterflies for free if you need them.


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I appreciate that. Let me see how flat I can get these first.

[Paul Workman]

Time to just omit the secondaries altogether. :thumbsup: I have a set of butterflies if you need them.
H
:cheers:

That'd be MY vote too!!:thumbsup:

[HAWAIIZR-1]

Wow! I?ve never seen bent butterflies. If I didn?t need secondaries for emissions I would yank mine too.


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[Paul Workman]

Wow! I?ve never seen bent butterflies. If I didn?t need secondaries for emissions I would yank mine too.


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With the ECM software in the full time secondary mode, except for idle, the injector pulse width duration is split between the primary and secondary injectors. Maybe the "swirl" that goes on in the "NORMAL" mode that could have an effect on emissions. But, that I'd have to pass onto someone like Marc Haibeck who might know if it matters. I mean, the gen-III LT5 had bu one injector/cylinder, IIRC. But, too, they had some fancy lifter architecture too, if memory serves.

So...IDK if deleting the secondary butterflies and running both of the injectors (albeit at half throttle) would be an issue, emissions-wise. It's an open question...

[HAWAIIZR-1]

With the ECM software in the full time secondary mode, except for idle, the injector pulse width duration is split between the primary and secondary injectors. Maybe the "swirl" that goes on in the "NORMAL" mode that could have an effect on emissions. But, that I'd have to pass onto someone like Marc Haibeck who might know if it matters. I mean, the gen-III LT5 had bu one injector/cylinder, IIRC. But, too, they had some fancy lifter architecture too, if memory serves.

So...IDK if deleting the secondary butterflies and running both of the injectors (albeit at half throttle) would be an issue, emissions-wise. It's an open question...

Hey Paul,

Thanks for your thoughts. When I asked Marc before he advised I should keep secondaries operational for best chances to pass emissions in Japan. I even had him install A.I.R. tubes and EGR hookup in my SW short tube headers (that I still need to install). Yet, one of the Japan brothers posted on the FB Z Registry page that he is removing or bypassing secondaries so I?ll ask his plans for emissions.

Sorry OP for the intrusion to your post. 🤙🏼