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Hey guys, I picked up a white 1991 ZR from across state lines a few hours away from me. I've been stalking this one for about two years as it changed hands a few times in for sale ads outside of this forum. It was in surprisingly great condition and even has the original windshield. All weatherstripping is in excellent shape and the paint is fantastic with only a few pin head sized areas chipped from being driven as it should be. It even came with the pizza box with the original items and the window sticker. it's going to need a bushel of little fixer upper items addressed and maintenance performed soon on all fluids, including a new set of tires all around. One nice add on is the Corsa exhaust. Car has about 81k for mileage. Ultimate goal for the car is extremely boring: as close to factory original as possible, so it won't end up becoming a hollowed out shell of a rat rod like the 85.
I'll finally join the ZR-1 registry...probably make a cheesy unoriginal name like 1991 Corvette ZR-1 to match my 1985 Corvette handle on this site. Big shout out to FASTAZU and Cuisinartvette who provided details on the various Zs I found that I picked their brains on. FASTAZU also sent new for sale ads my way even on the very day I was getting the title signed over to me on this 91. And a big thanks to everyone else in this section who offered helpful info on my last inquiry. And like they say, "pics or it didn't happen".
Thanks guys. Should have the FSM, 8A manual and the LT5 supplement manual soon but can you guys take a look at this wire? Single blade red wire on the driver side looks to go to a sensor or tie into a sub harness? It's in the bottom right of the pic, I got more of the engine in the shot to show where it is in relation to the engine. ECU is just out of the shot in the bottom of the pic.
Last edited by 1985 Corvette; 09-02-2018 at 10:16 AM.
Thanks guys. Should have the FSM, 8A manual and the LT5 supplement manual soon but can you guys take a look at this wire? Single blade red wire on the driver side looks to go to a sensor or tie into a sub harness? It's in the bottom right of the pic, I got more of the engine in the shot to show where it is in relation to the engine. ECU is just out of the shot in the bottom of the pic.
Congrats! Good to see you finally found one. Be sure to check in over at the ZR1.net forum as well. The wire is normally like that. It’s a diagnostic connection the runs the fuel pumps if you apply power (12v) to it.
H
Great to hear! A few more questions and I'll start doing some digging through the forum FAQs. The previous owner did a coolant bypass but I do prefer the stock look, so I had plans to return the hoses back to their original locations on the plenum. I'm not even really sure how worth it this mod is on this engine. I'm guessing the small air pockets made from cutting the hose to correct size and pushing them onto plenum ports should be burped out of the system on their own and a non issue right? I have the throttle body gasket to install as well.
Also, per the previous owner, the car has a Haibeck chip installed that keeps the secondaries open all the time. This means the valet key whether switched on reduced or full engine power is moot. It was "estimated" that an extra 10-15 hp was a benefit from the Haibeck chip but not sure this is worth having the secondary system open all the time? I do like the idea of having a functional valet key...even at the cost of a few horsepower. If I wanted to return to the factory setting would I be able to install the factory Z prom without issue or are these in short supply? Not something I will mess with just yet just curious.
First question leave the bypass it will keep the throttle body paint from having issues around the small cover like this. As far as the chip you can send it back to mark and have it changed, it does have some nice features as fan settings cooler. You need to also check and be sure the secondary's are not tied open.
Congrats on your new Z,you have no idea what your in for and that’s a good thing. As stated the bypass will keep the paint around the TB from corroding. The baypass can be done so it’s barely noticeable,I ran some dummy hoses from the nipples on the TB down under the plenum. If you decide to go to the stock PROM you just might regret it,every time the car is started the VALET MODE reverts to to lower power setting,must be switched to full power each time the car is started.
1) the plenum is the heat sink for the DIS module. Thankfully they are very robust, but are a critical short supply. Keeping the plenum cooler IS a step in the direction of reliability.
2) the by-pass simplifies removing the plenum. No need to drain some coolant (a gallon or so) and then putting it back after.
3) if you install coolant plugs in the injector housing to block TB coolant, you can run keep the stock appearance and still have the benefits of by-passing the TB.
You live in FL. Not likely you'll ever need heat to avoid frosting up the throttle body anyway!
Congratz on your Z! Do join the Registry too. Lots of folks and resources and a very tight-nit club. Welcome to the madness!
Paul.
PS:
This is my LT5 with the coolant blocked to the TB. But, from the looks of it, nobody would know anything had been done to it (hoses look stock. I like the "sleeper" appearance aspect).
Last edited by Paul Workman; 09-05-2018 at 09:49 AM.
Great to hear! A few more questions and I'll start doing some digging through the forum FAQs. The previous owner did a coolant bypass but I do prefer the stock look, so I had plans to return the hoses back to their original locations on the plenum. I'm not even really sure how worth it this mod is on this engine. I'm guessing the small air pockets made from cutting the hose to correct size and pushing them onto plenum ports should be burped out of the system on their own and a non issue right? I have the throttle body gasket to install as well.
Also, per the previous owner, the car has a Haibeck chip installed that keeps the secondaries open all the time. This means the valet key whether switched on reduced or full engine power is moot. It was "estimated" that an extra 10-15 hp was a benefit from the Haibeck chip but not sure this is worth having the secondary system open all the time? I do like the idea of having a functional valet key...even at the cost of a few horsepower. If I wanted to return to the factory setting would I be able to install the factory Z prom without issue or are these in short supply? Not something I will mess with just yet just curious.
Generally, the Haibeck secondary open mod is done with a secondary delete or wired open. Also, he warns to always leave the key in the "full engine power" mode otherwise you may get a lean condition. Maybe your previous owner did something different idk. Look for the main vacuum line coming off the secondary vacuum. If it's still connected you'll need to look further as they may be wired open. You can probably see one of the actuators with a flashlight according to Mark's diagnostic test if I remember correctly. FWIW if the secondaries are deleted I'd leave it that way. The vacuum on my car gave me fits. Congrats on the purchase!!
09-01-2018, 08:37 PM
Finally clawed my way into the group
Yes it is a diagnostic connector. 
