i am doing a secondary delete tomarrow for....

[sammy]

a friend . we have marks prom allready . is there any tip someone can share as to the best way to wire open the secondaries .thanx for any help you can provide

[GOLDCYLON]

Dom did this fairly recently as did Andrew I believe

[ZR1@gmx.com]

a friend . we have marks prom allready . is there any tip someone can share as to the best way to wire open the secondaries .thanx for any help you can provide

It is fairly straight forward to just remove the plates, bearings and all, then plug the holes. I think I have some photos I will try to dig up!

[sammy]

the person i am doing it for doesnt want to remove the plates or butterflies as he will have to pass ca smog once every 2 years . do we have to remove the actuators? and what does everyone use to keep them open /?

[mike100]

what if you leave the actuators for now and just hook them to manifold vacuum?

that will force them open to test out your chip function. Other than that, I almost want to suggest an old fashioned pull cable like on a choke for a carbed car. need to do it twice though.

[Paul Workman]

what if you leave the actuators for now and just hook them to manifold vacuum?

that will force them open to test out your chip function. Other than that, I almost want to suggest an old fashioned pull cable like on a choke for a carbed car. need to do it twice though.

Well, a little easier than that, actually. Dom used a plastic tie-wrap to strap the throttle plates open.

Also, you then need the chip programmed to run the secondary injectors "full" time and halve the primary dwell time (closed loop). The vacuum line is disconnected from the vacuum sensor to be exposed to atmospheric pressure which the new program reads as "normal" i.e., no codes are thrown sans vacuum.

To return to stock, just snip the tie-wraps, swap the chip, restore the vacuum circuit and it's good to go.

But, ya know...I would be tempted to see if it would pass emissions testing with the secondaries open. The stock tune at the low end of the rpm band, according to Marc, is a little "fat" anyway. So...it raises the question: Will it pass regardless of the secondary system being nulled? Just a thought.

As for the "choke cable" scenario, that is intriguing! An external actuator, if you will, would eliminate a plenum pull. Tho pulling the plenum is a snap, (once you do it a couple times to establish a routine) the fewer times those connectors are pulled apart and reinstalled...the better, I recon!

P.

[Paul Workman]

Dom did this fairly recently as did Andrew I believe

Yep. But, that was on the car he wrecked. His "Roza Nero" has the secondaries removed entirely (he said last Saturday).

P.

[VetteMed]

No secondaries here! Love it!

[GOLDCYLON]

When the new block goes in Im doing this as well. Andrew are there any SES codes when you do this ?

[VetteMed]

When the new block goes in Im doing this as well. Andrew are there any SES codes when you do this ?

First time around I had some lean codes, even with the Haibeck chip. However, those disappeared after new FIC injectors and new fuel pumps were installed. Not a peep out of the ECM since then :cheers:

Andrew

[GOLDCYLON]

First time around I had some lean codes, even with the Haibeck chip. However, those disappeared after new FIC injectors and new fuel pumps were installed. Not a peep out of the ECM since then :cheers:

Andrew

Cool. Lean codes? Now thats a Hoot. Would not be codes I would expect

[VetteMed]

Cool. Lean codes? Now thats a Hoot. Would not be codes I would expect

Well, think about it - you're doubling the airflow to each cylinder - if fuel delivery is not up to par, due to a clogged injector, low fuel pressure, etc, then the mixture will be lean. The Haibeck chip changes the injector programming so that both injectors fire any time the throttle is off idle, but obviously that's only as good as the quality of the injector performance, and fuel delivery to the injectors!

[A26B]

"Doubling the air flow" is not exactly accurate. Without the secondary throttle system operating, "impeding" or "restricting" is more accurate. An engine is essentially a positive displacement air pump. It's only going to take in so much air, directly proportional to the displacement. In operation, the secondary throttle system is like a supermax port job.

[VetteMed]

"Doubling the air flow" is not exactly accurate. Without the secondary throttle system operating, "impeding" or "restricting" is more accurate. An engine is essentially a positive displacement air pump. It's only going to take in so much air, directly proportional to the displacement. In operation, the secondary throttle system is like a supermax port job.

Jerry, perhaps in the interest of brevity I over-simplified. When the secondary system is either removed, or latched open, it's allowing all 16 intake runners to feed air to the cylinders. This is double the air compared to what is delivered when the secondary throttle plates are closed. If the secondary fuel injectors are not delivering fuel (due to faulty injectors, poor fuel pressure, or an ECM command to not fire), but the secondary throttle plates are open, there's bound to be a lean mixture.

In my situation, the immediate lean mixture led to a code being set, which then caused the ECM to completely disable the secondary injectors, while the throttle plates were still open (nonexistent).

I am not under any false illusion that simply removing the secondary system doubles the potential airflow through the secondary intake ports.

Hope this clarifies what I was getting at. ;)

[PhillipsLT5]

No secondaries here! Love it!
Ditto

[Kevin]

i really need to drive a no secondary car, and I don't mean romp on it type of drive, but just a cruise around town to see how it deals with every day driveablity

[PhillipsLT5]

Hard to tell the difference with or without them except more power now and less junk in the way

[XfireZ51]

Gentlemen,

The motor is going to use X amount of air and fuel at a given throttle opening. Simply activating the secondaries doesn't "make" the motor use more air/fuel. At part throttle cruise, the amount of air/fuel charge is going to be delivered either by one port and one injector OR split between two runners and two injectors. The fuel tables in the cal only deal with total VE at a given MAP, fuel delivered either by one or two injectors. Wth proper tuning, the difference in single or double runner cruising should be not very discernible especially if mods are done to move more air through the system(i.e. headers, freer exhaust)

[VetteMed]

Gentlemen,

The motor is going to use X amount of air and fuel at a given throttle opening. Simply activating the secondaries doesn't "make" the motor use more air/fuel. At part throttle cruise, the amount of air/fuel charge is going to be delivered either by one port and one injector OR split between two runners and two injectors. The fuel tables in the cal only deal with total VE at a given MAP, fuel delivered either by one or two injectors. Wth proper tuning, the difference in single or double runner cruising should be not very discernible especially if mods are done to move more air through the system(i.e. headers, freer exhaust)

Agreed 100%, makes perfect sense.

[sammy]

guys first off thanx for all the responses/help. . this really was an easy job to do .we used aircraft wire to wire the secondaries open. we pulled all the vacum tubing and pieces . i also had to replace the starter motor as the dealership that he bought the steamed cleaned the motor before he too k delivery . it sure is one nice 90 the metalic rad paint with manual air and polished stk 90 wheels . the grin on his face was worth the 230 mile trip one way to help him . he was so frustrated he wanted to sell the car .but i told him our cars make us earn the right to own them and this was just a test.lol also told him his new mistress liked it rough, that the more you beat on her the happier she is . the look on his face was priceless

[sammy]

oh ps i am going to do this to both my cars asap. car seems to have more spunk in the low to mid range .and one has confedance that they are indeed open all the way

[sjs]

Excellent post everyone, I sure learned alot! Thanks to Kevin for turning me on to this post. I never would have believed driveability would have improved until everyone here said it did. Ironically, the same SAE that all the Vette engineers belong to preaches the EXACT OPPOSITE of what everyone experienced in the real world. Their combustion theory - intake vs cam design states clearly that doubling the intake area cuts velocity and turbulence in half - thus reducing horsepower and torque under 4000 rpm. Same as the old school guys comparing tunnel rams and dual plane intakes under carbs. Also the original purpose of this system was to run like an L98 motor with gobs of torque down low then open up the are with the secondarys and larger cam lobes under them later. ... ????
But since everyone is finding out otherwise and the car runs better without this system in place it must mean the cams are not much different from the primary to secondary ports .... does any one else agree ??? Or does anyone make an aftermarket truly "dual personality" CAM with monster torque for the primaries and long duration on the secondaries to make a real monster out of this motor?

[Kevin]

you're welcoms sjs, we're all here to learn

[tomtom72]

http://www.zr1.net/forum/showthread.php?t=11411&highlight=shafts

sjs, you might find this thread an interesting read concerning cam shafts.


:cheers:
Tom

[Paul Workman]

...But since everyone is finding out otherwise and the car runs better without this system in place...

One of the first things I did was yank the secondaries, and I have NO regrets. IMO, the throttle response is quicker - has to be, cuz there is no delay between the throttle plates opening and the secondaries being switched on; both are already on. WOT, according to my dyno brag sheet gave up nothing in the low/mid range**.

Drivability is better than before pulling the secondaries, actually. But, part of its manners now come from new (Accel) injectors, after it was discovered the replacements put in before I bought the car were NOS with the same suseptibility to alcohol as before, and after 3 seasons had started to go bad again.:-x And, I give credit too to Marc Haibeck's calibration. He does some fuel modifications and ups the idle a bit to speed the air flow at idle a little. (He also changed the management of the cooling fans, which I like a LOT as well!)

So, combined with the new calibration, it isn't exactly clear (to me) what the reason for the better street manners is: sans secondaries or the cal?? But, none the less, I'm VERY happy with the delete in combo with the new calibration which also addressed some of the (high) idle issues known to the original factory cal for the 90 MY.

**Independent and revised I/O cam timing may well have a lot to do with not affecting the original torque curve at the low/mid range. Again, this is a variable that doesn't have bearing on a single cam, pushrod motor. (Like having your cake and eating it too!) I'm no expert to tuning DOHC LT5s, but Pete, Marc, Bob G (FBI gurus) are. From the graphs (make that "wallpaper"!) on display in Marc's office and the results at the track by Pete (especially), it stands to support the supposition that when it comes to predicting performance characteristics resulting from certain mods, those with pushrod experience exclusively are beyond their depth when discussing DOHC (LT5s). (Maybe the GM guys should go over to Ford to see what they're doing with a 5.0L these days!) These LT5s are very interesting power plants, to be sure!

P.

[PhillipsLT5]

I picked up torque & RWHP also, no driveability issues