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Secondary Throttle System Delete Question

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Old 08-20-2017, 07:31 PM
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KJL
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Default Secondary Throttle System Delete Question

I am wanting to remove the vacuum components that support the secondary throttle system fro my 92. I am doing this to preserve those components. Planning on wiring the secondaries open for now. I noticed the driver side secondary throttle plate actuator T's off to what my manual refers to a vacuum switch. I assume this is part of the secondary system? Will removing the vacuum source from this switch affect any other systems?

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Old 08-21-2017, 08:44 AM
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Originally Posted by KJL View Post
I am wanting to remove the vacuum components that support the secondary throttle system fro my 92. I am doing this to preserve those components. Planning on wiring the secondaries open for now. I noticed the driver side secondary throttle plate actuator T's off to what my manual refers to a vacuum switch. I assume this is part of the secondary system? Will removing the vacuum source from this switch affect any other systems?

Thanks!
First: Jerry's Gaskets carries the complete vacuum secondary actuator system. So, that may affect your decision to remove the circuit and tie the SPTs open, no?

Second: On my 90, the switch is under the ECM, and on the 91+ it is under the plenum. The vacuum line can be removed, but the switch remains, signalling the ECM. However, the ECM calibration has to be changed to accept ZERO vacuum signal as "normal". The switch REMAINS connected to the ECM. The rest of the vacuum circuit may go.

Note: The re-calibration of the ECM for deleting the secondaries typically includes re-programming which addresses that switch, along with turning on the secondary injectors (at just off idle) full-time. This provides cleaning of the secondary valve - a trade-off for slightly less low-end torque. Also, this switch is attached to the underside of the ECM in the 1990s, but is under the plenum from 91+.
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Old 08-21-2017, 08:56 AM
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Thanks for the info, I was planning on having Marc do the chip for me. I will double check with him regarding the switch. I am still on the fence regarding removing the system. I am also blocking the coolant to the plenum and TB so I guess if I don't like it, I can always put it all back to normal with little trouble.
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Old 08-21-2017, 05:51 PM
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Originally Posted by KJL View Post
Thanks for the info, I was planning on having Marc do the chip for me. I will double check with him regarding the switch. I am still on the fence regarding removing the system. I am also blocking the coolant to the plenum and TB so I guess if I don't like it, I can always put it all back to normal with little trouble.
the beauty of this mod is that if you just wire em open, and plug off the vacuum (no longer needed) you are ready to try it out

all you will notice is a bit sharper throtte response, improved mid range, and cleaner secondary injectors and valves

other than that, nuttin

parts left out don't break, later, you will offer up all these little jiggles and wiggles that open up the secondaries you have long since grown to NOT miss and port the heads to really enjoy what makes this mod work

aggressive porting
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Old 08-21-2017, 05:59 PM
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Originally Posted by KJL View Post
Thanks for the info, I was planning on having Marc do the chip for me. I will double check with him regarding the switch. I am still on the fence regarding removing the system. I am also blocking the coolant to the plenum and TB so I guess if I don't like it, I can always put it all back to normal with little trouble.
I can honestly say, that after having eliminated the secondaries some 5-6 years ago, I haven't a moment's regret! Nothing not to like, and a whole lot of plus items to like!

I notice you're in Roswell, GA. Marc and Russ too are in the Marietta/Powers Ferry area. Maybe we can get together in Dec to tip a couple in a sort of ZR-1 gathering when I come to Atlanta to visit? Just a thought!
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Old 08-22-2017, 01:46 PM
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ahhh.... I remember the days fondly with Jim Smith tuning on the LPE at Aaron Scott's place

absolutely there are some "flying doc's" for the ZR-1

with a dyno and the right setup, it's pretty easy to remote tune

road runner eliminates much of the trial and error and allows you to tune much and burn once to set the memcal

I'm really interested in continuing the megasquirt project and just "cut into" the wiring harness like they do on the c5 so the dash controls continue to talk to the interfaces on the factory stuff

that way we don't lose the mileage and security functions.

the megasquirt will also allow coil on plug, much improved auto correction and wide band, and many more functions to get ready to TT the big doggie

I've learned a lot on the C5 car, and I'm anxious to reapply some of that back to the TT LT5 project

good old Will ruined me for the LSV
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Old 08-22-2017, 08:07 PM
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Originally Posted by Rkreigh View Post
the beauty of this mod is that if you just wire em open, and plug off the vacuum (no longer needed) you are ready to try it out

all you will notice is a bit sharper throtte response, improved mid range, and cleaner secondary injectors and valves

other than that, nuttin

parts left out don't break, later, you will offer up all these little jiggles and wiggles that open up the secondaries you have long since grown to NOT miss and port the heads to really enjoy what makes this mod work

aggressive porting
I am also doing my own plenum and IH's porting. I have a post showing the progress. Almost done. Last thing to do is port match the heads to the IH's. Mostly just the primaries.
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Old 08-22-2017, 08:08 PM
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Originally Posted by Paul Workman View Post
I can honestly say, that after having eliminated the secondaries some 5-6 years ago, I haven't a moment's regret! Nothing not to like, and a whole lot of plus items to like!

I notice you're in Roswell, GA. Marc and Russ too are in the Marietta/Powers Ferry area. Maybe we can get together in Dec to tip a couple in a sort of ZR-1 gathering when I come to Atlanta to visit? Just a thought!
That would be great! Russ and I have tried to get together several times but life just keeps getting in the way. Let me know when and I will get it in my calendar.
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Old 01-13-2018, 02:58 PM
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Originally Posted by Paul Workman View Post
I can honestly say, that after having eliminated the secondaries some 5-6 years ago, I haven't a moment's regret! Nothing not to like, and a whole lot of plus items to like!

I notice you're in Roswell, GA. Marc and Russ too are in the Marietta/Powers Ferry area. Maybe we can get together in Dec to tip a couple in a sort of ZR-1 gathering when I come to Atlanta to visit? Just a thought!
Sorry we could not get together in December. Always much going on that time of year. My car is finally on the road and running great. One thing I wanted to point out that I leaned from Marc about the secondary delete chip is you can still turn the secondaries off at the power key and if the check engine light ever comes on, the ECM automatically shuts the secondary injectors off. So you need to "limp" home in order to not burn your engine up.

I have never seen anything mentioned about this on the forum and think it would be a good idea to mention this on his web site.

Per Marc:
It's important to never turn it off. Doing so would cause the engine to run lean at over 50% load. Also note that if the engine gets a "Service Engine Soon" error the secondary fuel injectors will be turned off even though the green LED would remain on. If you ever get a Service Engine Soon error the car can be safely driven at less than 50% load and under 3000 rpm to limp it home.

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Old 01-14-2018, 06:00 AM
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Originally Posted by KJL View Post
Sorry we could not get together in December. Always much going on that time of year. My car is finally on the road and running great. One thing I wanted to point out that I leaned from Marc about the secondary delete chip is you can still turn the secondaries off at the power key and if the check engine light ever comes on, the ECM automatically shuts the secondary injectors off. So you need to "limp" home in order to not burn your engine up.

I have never seen anything mentioned about this on the forum and think it would be a good idea to mention this on his web site.

Per Marc:
It's important to never turn it off. Doing so would cause the engine to run lean at over 50% load. Also note that if the engine gets a "Service Engine Soon" error the secondary fuel injectors will be turned off even though the green LED would remain on. If you ever get a Service Engine Soon error the car can be safely driven at less than 50% load and under 3000 rpm to limp it home.
On my 90, I jumpered the switch against future mechanical issues or accidentally turning it off. Same thing too on the 91.
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Old 01-16-2018, 09:53 AM
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Originally Posted by Paul Workman View Post
On my 90, I jumpered the switch against future mechanical issues or accidentally turning it off. Same thing too on the 91.
Could you elaborate? There are two issues that cause the secondary injectors to turn off, one is the actual switch and the other is a check engine light. Are you saying you jumpered both? Is it possible to just remove the key in power mode? Never tried.
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Old 01-16-2018, 06:12 PM
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Originally Posted by KJL View Post
Could you elaborate? There are two issues that cause the secondary injectors to turn off, one is the actual switch and the other is a check engine light. Are you saying you jumpered both? Is it possible to just remove the key in power mode? Never tried.
The 90 ZR-1 FULL ENGINE POWER mode cannot be programmed. It can only be activated by manually activating a mechanical, fallible switch, assuming certain criteria have been met (of course).

So, by soldering a jumper across the switch' s connections prevents inadvertently opening the connection, resulting in 1/2 of the fuel being shut off (SES lights asside).
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Old 01-16-2018, 11:38 PM
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Default 91' Eliminated Secondaries Completely

See LT5 Eliminated Systems

Marc Haibeck's Custom Chip can set the Default Power Setting to Full Power (91'-95').

Marc's Default Power setting is Full Power on my 91'

Last edited by Dynomite; 01-16-2018 at 11:46 PM.
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Old 01-17-2018, 10:43 AM
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I just leave mine(90) in full...is there a problem with that?
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Old 01-17-2018, 02:46 PM
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Originally Posted by biggiefl View Post
I just leave mine(90) in full...is there a problem with that?
Well, maybe...

There's no problem...up until the contacts in the switch corrode or get dirty, OR it gets accidentally switched OFF maybe. (It was the latter case that "got me".)

So, I hard-wired the leads together - eliminating the switch function absolutely/completely! Ami's 91 could be programmed, but apparently isn't; it has a toggle switch wired across the momentary ON (dash) switch that is inside the console glove box. I need to "fix" that, I recon!
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Old 01-18-2018, 07:04 PM
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great point on the early cars.

on the later model cars the power key works different and can be programmed to "default on"

I always wondered what would happen if I switched it off by mistake.

I think it's "ignored" on the 91 and up if programmed on

Marc also turns off the air pump, as if it fails and it's not "programmed out" you will get an annoying code for port secondary operation even thought they are gone because the ECM sees the pump isn't working or something like that.

Anyway, I was one of the "early adopters" of no secondaries on the LSV and that step was missed. Many years later my air pump failed and I started getting an intermittent code (as soon as vacuum drops) that would go on and off as I drove the car. No problem with secondaries, just annoying.

I didn't know what the heck was happening until we looked in the chip cal and saw that setup to comment out that error routine for low vacuum was was not applied.

I too worried how the car would react at WOT with a check engine light coming on and potentially dropping the secondary injectors just when you need that fuel big time. It would be very scarey if you nail it and hold the throttle down running dead lean at dead lean going WOT.

No bueno. I think an AF guage with an alarm is wise in addition to "jumpering around" this switch so don't accidentally toast an expensive LT5

thanks for bringing this up, I've been curious about "risks" of the secondary delete!!

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Old 01-18-2018, 09:48 PM
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Originally Posted by Rkreigh View Post
great point on the early cars.

on the later model cars the power key works different and can be programmed to "default on"

I always wondered what would happen if I switched it off by mistake.

I think it's "ignored" on the 91 and up if programmed on

Marc also turns off the air pump, as if it fails and it's not "programmed out" you will get an annoying code for port secondary operation even thought they are gone because the ECM sees the pump isn't working or something like that.

Anyway, I was one of the "early adopters" of no secondaries on the LSV and that step was missed. Many years later my air pump failed and I started getting an intermittent code (as soon as vacuum drops) that would go on and off as I drove the car. No problem with secondaries, just annoying.

I didn't know what the heck was happening until we looked in the chip cal and saw that setup to comment out that error routine for low vacuum was was not applied.

I too worried how the car would react at WOT with a check engine light coming on and potentially dropping the secondary injectors just when you need that fuel big time. It would be very scarey if you nail it and hold the throttle down running dead lean at dead lean going WOT.

No bueno. I think an AF guage with an alarm is wise in addition to "jumpering around" this switch so don't accidentally toast an expensive LT5

thanks for bringing this up, I've been curious about "risks" of the secondary delete!!
It is not ignored. Per Marc, it can still be switched off even if programmed to turn ON when the car is started. A check engine light will also turn it off.
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Old 01-19-2018, 11:49 AM
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Originally Posted by KJL View Post
It is not ignored. Per Marc, it can still be switched off even if programmed to turn ON when the car is started. A check engine light will also turn it off.
wow, thanks, we were discussing this problem. Are you sure a check engine light will deactivate secondaries?

I wasn't going WOT but I had the vac pump issue with the cel on and the car still made gobs of power and didn't experience any hesistation.

I've got a 95 better keep my hand off that key, at least it defaults to ON
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Old 01-19-2018, 12:01 PM
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Originally Posted by Rkreigh View Post
wow, thanks, we were discussing this problem. Are you sure a check engine light will deactivate secondaries?

I wasn't going WOT but I had the vac pump issue with the cel on and the car still made gobs of power and didn't experience any hesistation.

I've got a 95 better keep my hand off that key, at least it defaults to ON
My question to Marc was regarding my 92 so I can say for sure if his reply was for all model years. I think this info should be posted on the ZR1 web site as well and more clarification from Marc. Hate to see any of these incredible engines damaged for any reason.
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