Issue or not?

[RichS]

No codes stored. Pulled plugs and they look decent but I was replacing them anyway. I did notice the vacuum pump runs then shuts off, but does cycle for a second every 10-15 sec. I hood up my mity vac and pulled a vacuum on the line going under the plenum. It falls pretty quick once I pull it down to 25". Are the actuators suppose to hold the vacuum, or guess I'll be pulling the upper plenum.

I do realize these are an upper rpm motor, but I really expect to be pulled into the seat up top and really don't feel that.

[Dynomite]

Originally Posted by RichS

No codes stored. Pulled plugs and they look decent but I was replacing them anyway. I did notice the vacuum pump runs then shuts off, but does cycle for a second every 10-15 sec. I hood up my mity vac and pulled a vacuum on the line going under the plenum. It falls pretty quick once I pull it down to 25". Are the actuators suppose to hold the vacuum, or guess I'll be pulling the upper plenum.

I do realize these are an upper rpm motor, but I really expect to be pulled into the seat up top and really don't feel that.

Pump on for a second or two and off for 10-15 seconds is rather normal (and very functional). Unless the vacuum connectors are replaced you will always get some leaks in the various connectors.

You can check Secondary Operation without removing the Plenum.

With the key on, ground the pink wire in the green connector (third from drivers side) on ECM. Use a small finishing nail stuck in alongside the wire connector with an alligator clip pigtail attached to the end for grounding. This will activate the Secondaries which you can watch between the Plenum Runners without removing the plenum. See Secondary Functional Test and Reconditioning the Secondary Actuators

You should eliminate TB coolant so you do not have to mess with coolant every time you remove the Plenum.
See Blocking TB Coolant, Fluidyne Radiator and Thermostats

[RichS]

Did the check, Actuators move smoothly, vacuum pump does the same when activated. Runs for a second or so while activating, then a quick 1/2 second after a minute or so. Actuators hold open the whole time.

[Dynomite]

Originally Posted by RichS

Did the check, Actuators move smoothly, vacuum pump does the same when activated. Runs for a second or so while activating, then a quick 1/2 second after a minute or so. Actuators hold open the whole time.

Secondaries and associated vacuum system are NOT an issue
Could be injectors

[Z51JEFF]

If you romped the pedal in 2nd gear on 22 year old tires that thing should spin like its on ice. My 91 had the original tires on it when I got it in 07. It was fun to hook it sideways at will when ever I wanted UNTIL I needed to haul @$$ to get around a stalled car at a stop light. I literally went through the intersection sideways looking through the pass window to see where I was going. Must have looked bitchin from the outside😁,it was beautiful,hooked sideways through the entire length of the intersection.Now not stupid sideways sawin wood,just this very nice front wheels cocked with the @$$ end of the car kicked out to keep it going forward. After that,not so much fun.

[RichS]

Once I get it put back together I'll have to check it further. Figure check fuel pressure and scan it while driving. Windows getting tinted today. Debating on doing the 4:10 gears this weekend too, along with a lowering kit, brakes and rotors, hid fog light, head lights and molded splash guards once they get painted.

So far I replaced the fuel filter, oil and filter, Plugs (easy), Belt (sucked), clutch fluid. Plugs were NGK iradium gapped at .060.

[Z51JEFF]

Did somebody saaaaaaaaay,lowered?[IMG][/IMG]

[RichS]

Checked the fuel pumps, 9.8 amp so they both run.... Starting to think it might be me, lol. I just used the bolts and wedges lowering the GS and it's pretty low..

[BigJohn]

Originally Posted by RichS

Once I get it put back together I'll have to check it further. Figure check fuel pressure and scan it while driving. Windows getting tinted today. Debating on doing the 4:10 gears this weekend too, along with a lowering kit, brakes and rotors, hid fog light, head lights and molded splash guards once they get painted.

So far I replaced the fuel filter, oil and filter, Plugs (easy), Belt (sucked), clutch fluid. Plugs were NGK iradium gapped at .060.

Tinted windows so you don't want to be seen driving it!

[BlackSheepz]

Here is a strange non mechanical suggestion. Drive her more.

When I got my 90 ZR-1 I was a little disappointed as well because my 92 literally whips my head back in the seat off the line. The ZR-1 does no such thing even though according to the Dyno it's not all that far behind in Torque, and it absolutely will spin the tires in first and second gear. My wife had the same response that yours did until we needed to pass someone on the highway one time. She then knew why this car was special. Just recently I also met another guy at Marc Haibecks shop who bought a 90 ZR-1 while owning and racing a 96 Grand Sport. He had the same experience as you and I.

Move to just shy of a year and 4500 miles later. (Including 2100 miles driving her home).

I can now tell an incredible difference in driving them. I still love driving my 92 around town and have zero interest in selling her, but she runs out of breath soooo fast and when she is at the top of her RPM range she just feels like she has nothing left to give. If my Z is up to any speed at all whatsoever she drives and accelerates like ghost rider just lit his head on fire and now that I know where to look for it, I can definitely feel it. The LT5 is just significantly more smooth than the LT1/LT4 which is a blessing and a curse IMO. On any on ramp in a LT1 you'll feel the visceral push back all the way to 60 when she runs out of breath but in the same space you'll be up at 90+mph in the Z and not only will she will feel like she isn't even breaking a sweat but you'll be wondering how you are going so fast. You'll still only be in 2nd gear.

After a few hundred miles of driving your Z, you'll go back to the other car and you'll see the difference. Guaranteed. Easiest way to do this is to take her on a road trip of some sort for a weekend.

Another thing to note. The shift light comes on early in stock form. You can run her all the way to 7200 no trouble. Shift light comes on at 6500 stock I think? I don't remember, but I bet someone on here does.

Just my thoughts. My 90 has 30k miles and is stock including the injectors.

Edit: I forgot your GS is far from stock, yea your Z will feel slower than your 11 second GS but I'll stand by what I said. Drive her for a while and you won't be disappointed.