biggiefl

I am getting towards the end of my wits and my skills on this secondary issue. If it is not the fuel filter or the vac secondary pumps I am out of ideas and parts to replace. If anyone has a reputable ZR1 guy/gal they can recommend in my area, it would be greatly appreciated.

Dynomite

Do NOT give up yet

Do a Secondary Functional Test with Key On by grounding the pink wire with black strip on ECM and observing Secondaries function between the Plenum Runners

Secondary Functional Test and Reconditioning the Secondary Actuators

Rkreigh

Aaron Scott at SGC is nearby in Thomasville GA

Also Kurt White in Tampa

I kinda got frustrated like you and just had the secondaries removed with a reprogrammed chip

you can just wire them open if you like and remove the vac spider and quite a bit of misery (parts left out don't break)

but trouble shooting the factory stuff isn't too horrible either if you get a hand with it.

if you don't have the Factory Service Manual, it's time. I have one for 50 if you need one.

LOTS of ZR-1 folks in your neck of the woods. Reach out to the zr1 net reg and post up!!

Dynomite

I have removed secondaries on one 91' (Removed.....NOT wired open) and have restored the secondaries on a 95' and three 90's. Restoring the secondaries is relatively easy. And keeping the secondaires functional you maintain the most unique feature of the ZR-1 which is the FULL POWER Mode (Parts Left Out Change the Unique Features of the ZR-1)

P.S. I am on the ZR-1 Net Reg also with the INDEX called Solutions and I might just send you back here to the Sticky above

TOP END RESTORATIONS SUMMARY
Post 62 - 1990 (#2067) LT5 Top End Rebuild (C5 Z06./Wilwood Brakes, SW Headers, Aluminum Radiator)
Post 76 - 1991 (#1427) LT5 Rebuild (C5 Z06/Wilwood Brakes, SW Headers, Ron Davis Radiator)
Post 119 - 1990 (#3032) LT5 Top End Rebuild (Fluidyne Radiator)
Post 133 - 1990 (#0072) LT5 Top End Rebuild (Ron Davis Radiator)
Post 230 - 1995 (#0186) LT5 Specific Top End Rebuild (C5 Z06/Wilwood Brakes, Fluidyne Radiator)
Post 261 - 90’ (#8550) Corvette (L98) Modifications (SW Headers, Ron Davis Radiator)

biggiefl

Can I just wire tie them open to check if that is it(after grounding pink wire of course).

Dynomite

No.......The secondaries open only normally under specific Throttle and RPM conditions. Marc Haibeck Trigger Points for Secondary Operation


The Secondary Operational Test involving grounding the ECM wire will confirm all the mechanical parts are clear and working (not binding on anything). Will also confirm the secondary vacuum solenoid is functioning. The guys that wire the secondaries open have the Plenum off to accomplish that.

biggiefl

I am aware that I would need to remove the plenum to wire open secondary solenoids. I will reread your pages on rebuilding secondaries. My question is why can't one just leave them wired open? It's a closed system so should not be a problem and I would eliminate the need to open the secondaries. Sure you can remove them but why can't I just wire them open and basically it is full power all the time(which I leave it in anyways).

Dynomite

Lots of guys wire the secondaries open. You mean wire the Butterflies open (not the Secondary Solenoid). Some remove secondaries completely and some wire them open and some remove the butterflies and leave the shafts.....your choice. You will need a new chip to control the secondary injectors which would have to be operational under and at all conditions of throttle positions and engine rpm (which now the secondary injectors are operational under specific conditions). Marc Haibeck Trigger Points for Secondary Operation

I will find you some posts on wired open secondaries. Among these posts are several ways to wire/remove secondaries

Having an Operational Secondary Full Power Switch TIPS
What Conditions Allow/Cause Secondaries to Open TIPS
Secondary Functional Test and Reconditioning the Secondary Actuators TIPS
Secondary Failure at 5K rpm
Removing Secondary Shafts Engine In Car TIPS
Secondary Canister Installation FACTS TIPS
Removing Secondaries TIPS
Removing Secondary Vacuum System Questions TIPS
Secondary Canister Installation TIPS
Secondary Removal TIPS
Secondary actuator operation VIDEO
Secondary Vacuum Reservoir Source TIPS
Secondary port vacuum diagnosis TIPS
Eliminated Secondary Throttles/shafts Tricks
Secondary vaccum system removal
Secondaries removed picture
Remove secondary throttle plates and shafts
Dorman plug for removed secondary throttle shafts
Secondary failure
Upsidedown Secondaries
Secondary cannister failure
Ebay ZR1 LT5 Secondary

Paul Workman

w/ Cliff; good info.

As it happens, when I first got my 90 ZR-1, it behaved as you describe your aymptoms, including the mileage. Turned out to be that accordion air hose was collapsing. I made an aluminum liner for that hose which solved that issue. But, Marc Haibeck (ZR1 Specialist.con) sells wire hoops to insert inside the hose that also keep it from collapsing.

So, if you verify that the secondaries are opening,. I'd reinforce that air duct hose too, before looking further.

biggiefl

"So, if you verify that the secondaries are opening,. I'd reinforce that air duct hose too, before looking further."


Removed it last week and it made no difference, still falling flat around 5k.

Dynomite

Like this?

feels like rev limiter at 5,000 rpm in 3rd gear

A Vacuum Canister was not holding vacuum in this case.

zrracer

Kurt White has left the country.
By removing the secondaries in an already port and polished engine I would assume the engine will make more power down low where the butterflies were remaining closed and possibly make a little more hp/to
Do to that little better flow and a retune that allows for it?
TIA,
Robin

biggiefl

I finally fixed it.....375hp of pure bliss.

Rkreigh

you lose a small amount of torq below 2k.

the gain is a small amount of mid range. to really take advange of this mod the porting needs to be updated to take advantage of the secondary flapper being removed

for SURE you need the updated chip, you can't just wire them open.

Only thing I have noticed with the big LSV engine is that there is more rapid throttle response and of course no annoying air pump (geez these things are LOUD) or snakes nest to befuddle you.

Marc estimated leaving the secondaries in place only costs about 3 cfm, but for sure I recommend removing them and make sure you lock tite the little dorman plugs.

we managed to pop a few out making for a very nasty vacuum leak and another plenum pull.

where this mod can hurt is emissions. at low speeds keeping the secondary closed increases port velocity.

glad you got the beast going! what was it?

biggiefl

Tiny hard plastic vac line going to ecm was not in correctly

zrracer

I do not have it running yet. I have collected all the “stuff” needed to get it going though. I just need one more pulley.
I am in the middle of haveing the body kit installed.then I will get to the engine and then the interior. The kit has been a challenge I am on my second installer and about 8weeks into the installation. Maybe this weekend it will be done.