Secondaries not functioning - ZR-1 Net Registry Forums

TexasZR1 · 06-15-2019

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?

Young1 · 06-15-2019

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

Ccmano · 06-15-2019

Quote:

Originally Posted by TexasZR1

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 hot?

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.
Are you looking at both or just one?

I'm thinking it's the vacuum solenoid?
Its possible

Wiring diagram shows only one vacuum solenoid for the secondaries. Is this correct?
Yes 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?
You read this correct? http://www.zr1specialist.com/HAT%20W...%20Working.pdf

Also, anyone have a parts list for stuff to order for the plenum RR?
Just the plenum gaskets, replace the check valve while your in there it’s cheap and often causes problems.

Do I need to remove the throttle body to pull the plenum?
No

Do I need anything other than Jerry's "36 pc Fuel Injector Maint"?
injectors have already been replaced, no need to pull them again. Not part of the basic plenum pull process.
I've also seen recommendations to block some coolant ports?
Stick to one issue at a time although it does make a plenum pull a snap.

See my comments in RED above. With an intermittent and heat related problem like this and with vacuum holding when hot I’m inclined to think it’s more of an electrical issue. The solenoid is the only related electrical item under the plenum. I’m sure others will chime in. Keep us posted.
H

A26B · 06-15-2019

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

TexasZR1 · 06-16-2019

Quote:

Originally Posted by Ccmano

See my comments in RED above. With an intermittent and heat related problem like this and with vacuum holding when hot I’m inclined to think it’s more of an electrical issue. The solenoid is the only related electrical item under the plenum. I’m sure others will chime in. Keep us posted.
H

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.

TexasZR1 · 10-09-2019

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?

Young1 · 10-09-2019

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.

TexasZR1 · 10-09-2019

Thank you! Part ordered!

I found some other things to tighten and clean up while in there, so the plenum pull will have been well worth it.

Leaking pcv cover, lose injector housing bolts, will look more tomorrow.

Paul Workman · 10-09-2019

Quote:

Originally Posted by TexasZR1

*Power wise, I'm certain they are not opening (flat above 4500rpm).

Thanks everyone for the input! Will report back soon.

The stock "accordian" air hose between the air filter and the throttle body horn collapses under WOT and cuts off acceleration right at the 4500 +/- RPM you spoke of. It's a common issue with 26+ yr old plastic.

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!

Young1 · 10-09-2019

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!

06-15-2019	#1
TexasZR1 Join Date: Oct 2018 Location: Houston Texas Posts: 48	Secondaries not functioning 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? __________________ 1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator.

06-15-2019	#2
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 880	Re: Secondaries not functioning 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 __________________ 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.

06-15-2019	#4
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,376	Re: Secondaries not functioning 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 __________________ 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.

10-09-2019	#6
TexasZR1 Join Date: Oct 2018 Location: Houston Texas Posts: 48	Re: Secondaries not functioning 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? __________________ 1990 ZR1 #2184 BLK/BLK. Essentially stock. Plug-in Skip Shift Eliminator.

10-09-2019	#7
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 880	Re: Secondaries not functioning 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. __________________ 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.

10-09-2019	#10
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 880	Re: Secondaries not functioning 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! __________________ 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.