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Old 06-15-2019   #1
TexasZR1
 
Join Date: Oct 2018
Location: Houston Texas
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Default 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?
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Old 06-15-2019   #2
Young1
 
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Default 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
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Old 06-15-2019   #3
Ccmano
 
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Default Re: Secondaries not functioning

Quote:
Originally Posted by TexasZR1 View Post
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
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Last edited by Ccmano; 06-15-2019 at 12:34 PM.
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Old 06-15-2019   #4
A26B
 
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Default 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.


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Old 06-16-2019   #5
TexasZR1
 
Join Date: Oct 2018
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Default Re: Secondaries not functioning

Quote:
Originally Posted by Ccmano View Post
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.
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Last edited by TexasZR1; 06-16-2019 at 11:22 AM.
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Old 10-09-2019   #6
TexasZR1
 
Join Date: Oct 2018
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Default 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?
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Old 10-09-2019   #7
Young1
 
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Default 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.
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Old 10-09-2019   #8
TexasZR1
 
Join Date: Oct 2018
Location: Houston Texas
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Default Re: Secondaries not functioning

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.
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Old 10-09-2019   #9
Paul Workman
 
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Default Re: Secondaries not functioning

Quote:
Originally Posted by TexasZR1 View Post

*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!
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Old 10-09-2019   #10
Young1
 
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Default 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!
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