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#1 |
Join Date: Oct 2018
Location: Houston Texas
Posts: 40
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My secondaries started acting up with the heat lately.
They work fine when cold, then after warm-up (anywhere from 5 miles to 20 miles) they stop functioning. I first replaced the fuel pumps (they were original). Fuel pressure test shows ~40psi at idle and ~50 at WOT. Injectors were replaced by the prior owner. The vacuum pump is functioning properly (runs for about 10 seconds to build vacuum; cycles for about 1 second every 3 or 4 minutes). When jumping the pink wire at the ecm to ground, i get intermittent function of the secondary butterflys when warm. When it's cool, everything works great. I'm thinking it's the vacuum solenoid? Wiring diagram shows only one vacuum solenoid for the secondaries. Is this correct? I need to start ordering other parts (gaskets, etc) to pull the plenum. As a sanity check, any other diagnostic I should do first? Also, anyone have a parts list for stuff to order for the plenum RR? Do I need to remove the throttle body to pull the plenum? Do I need anything other than Jerry's "36 pc Fuel Injector Maint"? I've also seen recommendations to block some coolant ports?
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1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator. |
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#2 |
![]() Join Date: Sep 2016
Location: Ocala, FL
Posts: 889
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Because my Z is not a DD I always disassemble first, test and assess, then order parts. Maybe you have mice or lizards living in there! It is well worth the money to get Marc Heibecks DVD for your first plenum pull. zr-1 specialist.com
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Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much. |
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#3 | |
![]() Join Date: Jun 2006
Location: Sparks, NV
Posts: 2,852
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90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. Last edited by Ccmano; 06-15-2019 at 11:34 AM. |
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#4 | |
Join Date: Oct 2018
Location: Houston Texas
Posts: 40
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Thanks much for your help and guidance! Vacuum system is functioning well when cold and hot. I've looked at both actuators, however, when it doesn't function, neither do. When it DOES function, both move. I did read that diagnostic and a few others. I tried pretty well all I can with the plenum on I think. Given that grounding the pink wire works only when cold, the issue is almost certainly under the plenum. I have checked for codes and its all clear (12). The SES light does work, but it never illuminated when I'm having the issue. Power wise, I'm certain they are not opening (flat above 4500rpm). I will order a set of plenum gaskets, pick up some coolant, solenoid and check valve and see if I can get this sorted. Thanks everyone for the input! Will report back soon.
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1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator. Last edited by TexasZR1; 06-16-2019 at 10:22 AM. |
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#5 | |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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I fixed mine with a aluminum sleeve liner for that hose. Marc Haibeck sells some wire hoops to be inserted at intervals along the length of the hose, and Jerry's Gaskets sells a replacement hose which also adds to the esthetics. Get back 2 us!
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#6 |
![]() Join Date: Sep 2016
Location: Ocala, FL
Posts: 889
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Zip tie every vacuum and pvc joint you can. I got small brass round stock at Lowe’s. Formed it around the air horn and popped it inside the pleats. I think I put in 3 pieces. Easy and cheap. Runs to the rev limiter quite often too. You are welcome!
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Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much. |
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#7 |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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AND....Im sure you realize by now that it will run on secondaries FULL TIME. Many of us run on FULL ENGINE POWER, 100% of the time (above 1(?)% throttle input, IIRC). If you can pardon an old shade tree mechanics logic: "Parts that don't exist don't break, and they don't cost much!"
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#8 |
![]() Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,385
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Certain DTC’s will disable the Secondary port throttles, i.e. full power. If that is the case, you should see a light in the panel, usually SERVICE Engine Soon.
I suggest you check stored codes, make note of them, then clear all. Drive the car again under the same conditions that have disabled full power until it happens again, then check stored codes again. You may have a bad/missing light in the panel. This procedure will at least eliminate the possibility without having to disassemble anything. Sent from my iPhone using ZR-1 Net Registry
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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#9 |
Join Date: Oct 2018
Location: Houston Texas
Posts: 40
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I'm having a hard time locating a replacement vacuum solenoid.
Seems pn 1997222 is out of production and out of stock... Did I read there is a near twin to this part with a different bracket that can be substituted?
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1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator. |
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#10 |
![]() Join Date: Sep 2016
Location: Ocala, FL
Posts: 889
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https://www.rockauto.com/en/partsearch/?partnum=1997212
Type 1997212 into search of rock auto. This is what you need. Carefully change the bracket and cut a bit of plastic for the electric connector to fit. I did this myself about three years ago.
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Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much. |
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