Hauntingly familar secondary failure #3

[GOLDCYLON]

Originally Posted by chriskinzel

I'm in the process of removing my secondaries. Just pulled the shafts today with a new tool. It is a vice grip that has a slide hammer attached to it. Slicker than bacon grease! I put a nut on the shaft and with 3 hits from the slide hammer the shaft is out. Under 5 minutes to remove all 8. The shafts are bent, and unsealable, but so what I am throwing them anyway. I have got ant inspection camera and I will be checking all cylinders before reassembly. All of my screws are accounted for. (Maybe not all my marbles though).

Slick method Chris. Its the simple solutions that work

[Paul Workman]

Originally Posted by efnfast

Better air flow without the plates and rods in the way? I would assume yes, but a measurable difference?

Good question.

I asked Marc Haibeck about this some years ago, and if I recall, I believe he said it might be only 5-6 hp range (on an non-ported head)**.

Difficulties in controlling the variables in actual testing (using a actual LT5/dyno) are significant. And, theoretically the harsh** taper immediately following the SPTs may perhaps significantly obscure the effect on performance that removal of the SPTs (alone) might have had.

**Acoustics: Those that know seem to suggest that to practically eliminate reversion in the runner air column, the rate of change in diameter should be 4% or less. The change immediately below the SPTs on my (then stock) 90 heads was approximately 3 times that! However, if the head is ported, then that second restriction would be removed, and the effect of then removing the SPTs would be much more significant.


Either way...Performance wise (on so many levels) removing the plates and rods can't hoit!!

[zr-1.R1]

excuse my ignorance, I am a neophyte.
if I remove the plenum, and the secondary valves, insert the liquid stop screws, pull the bolt, then the car will give me error 61? and I change gas emissions?

[4-cam]

I removed the secondarys about two years ago while I was porting my top end after reading a thread about the screws and engine damage that can occur. There was no way I was going to let that happen to me. I have corys chip for secondary delete and my 91 passed the IM240 treadmill test here in Colorado with flyin colors. Im not as confident on how its going to do with the SW headers and high flow cats that I am installing now. I did add air tubes and will be ceramic coating headers and cats to keep them nice and hot. I am going to do an emmisions test before we start the tune to see what a difference high flow cats make. Hopefully she will pass without issues.

[Franke]

Originally Posted by 4-cam

I removed the secondarys about two years ago while I was porting my top end after reading a thread about the screws and engine damage that can occur. There was no way I was going to let that happen to me. I have corys chip for secondary delete and my 91 passed the IM240 treadmill test here in Colorado with flyin colors. Im not as confident on how its going to do with the SW headers and high flow cats that I am installing now. I did add air tubes and will be ceramic coating headers and cats to keep them nice and hot. I am going to do an emmisions test before we start the tune to see what a difference high flow cats make. Hopefully she will pass without issues.

So you removed the secondary's and still passed the IM240 test here. That's good to hear as I was thinking about doing that very mod but was worried about the emissions. Did you remove the sec throttle bar as well or just the throttle plates? I am curious to see how well your Z will pass with the hi flows and headers.

[4-cam]

I pulled the shafts. After that mod the emmisions test hardly looked any different than with the secondarys. I did install new accel injectors at the same time. I am currenty fabing up the exhaust. Once I get that all welded up and get ceramic coating done, I will give the emmisions a try. Most likley mid Febuary time frame.

[Schrade]

Originally Posted by Franke

So you removed the secondary's and still passed the IM240 test here. That's good to hear as I was thinking about doing that very mod but was worried about the emissions. Did you remove the sec throttle bar as well or just the throttle plates? I am curious to see how well your Z will pass with the hi flows and headers.

This is something that crossed my mind pertinent to OP.

Did the customer of Darryl's wrench-buddy attempt to do this - plate removal with shafts left in, then change his mind and re-install the screws???

[Paul Workman]

Originally Posted by zr-1.R1

excuse my ignorance, I am a neophyte.
if I remove the plenum, and the secondary valves, insert the liquid stop screws, pull the bolt, then the car will give me error 61? and I change gas emissions?

First, the ECM must be programmed for operating without the secondaries:

The new calibration will allow zero vacuum = OK (so no code 61)

At idle, only 1 injector is signaled "on". Above idle (>1%), the new calibration signals both injectors on but divides the dwell = 1/2 for each injector to provide the proper fuel.

Emissions might change. The tuning must be precise.

On a 1990, the POWER switch must ALWAYS = FULL POWER (VERY important!) For 1991-95 the ECM is programmed for the secondaries to always be "on".

All of the secondary circuitry may be removed (shown in PINK) and the plenum vacuum connection is plugged.

Note: On a 1990 ZR-1 the #11 "switch differential pressure" is located under the ECM. on 1991-95 the switch is under the plenum.

Note:...Please forgive me, but I don't understand what you mean by "insert the liquid stop screws, pull the bolt" = ???

Does this help?

[GOLDCYLON]

Originally Posted by Schrade

This is something that crossed my mind pertinent to OP.

Did the customer of Darryl's wrench-buddy attempt to do this - plate removal with shafts left in, then change his mind and re-install the screws???

Nope it just fell out. Mine fell out the same way on the drivers head of the motor then once again when the entire shaft broke screw and all and wedged two valves open on the passenger head. Once again it was not pretty as the pictures showed.

[GOLDCYLON]

Originally Posted by 4-cam

I removed the secondarys about two years ago while I was porting my top end after reading a thread about the screws and engine damage that can occur. There was no way I was going to let that happen to me. I have corys chip for secondary delete and my 91 passed the IM240 treadmill test here in Colorado with flyin colors. Im not as confident on how its going to do with the SW headers and high flow cats that I am installing now. I did add air tubes and will be ceramic coating headers and cats to keep them nice and hot. I am going to do an emmisions test before we start the tune to see what a difference high flow cats make. Hopefully she will pass without issues.

It wont pass with the high flow cats on the treadmill. Been there done that with Jeal Headers. Sniffer all day.