How Much Secondary Leakage?
 

Just how much does your secondary vacuum system leak?
With your ign key turned on and engine not running
how much time does your aux pump stay off.
That is, once it runs for a time (maybe it keeps running)
how long (in seconds) does the pump stay off?

PLEASE if you deleted the secondary do not vote.
PLEASE use actual numbers, don't guess.
If you have more than one ZR-1 sorry you can only vote once
(only because I blew it when setting up the poll)
If your aux pump keeps running then the off time is 0 seconds.

Re: How Much Secondary Leakage?
 

I Concur with Marc :cheers:
If the vacuum pump cycles 5, 10, 15 seconds or at all....the vacuum system is NOT TIGHT but normal and functional for the age of the vacuum system with components not replaced with NEW LINES AND NEW RUBBER (soft) CONNECTORS.

Disconnect the drivers side center plenum vacuum source and hold your finger over the rubber connector disconnected (Engine OFF but Key ON). IF THE SECONDARIES (Secondary Canisters) FUNCTION AND HOLD POSITION WHEN TESTING SECONDARIES WITH PLENUM IN PLACE (Key on) Verifying Secondary Actuator Operation with the Plenum in Place END OF DISCUSSION ;)

I will think further on this but for now I am busy planting corn and beans ;)

Re: How Much Secondary Leakage?
 

Bwwwahhhhh ha ha ha ha
After this we'll have a poll on how many still have their tire pressure sensors in place and leave their tire pressure at 26psi.
And how many run their cars on bald tires.

I just remembered. I still check the washer fluid
every now and then but almost never drive it in the rain.
Kinda funny.

But seriously ......
I don't think Mark H. is advocating NOT to fix your
vacuum leak, just that a 1 sec cycle time will not effect secondary operation. Of that I'm not sure I agree. What I do know is that
if you have a leak big enough to cause a 1sec cycle time then there's not much wiggle room before you're at a bigger leak where as the pump runs constantly and you'll get a code 61 and loss of power above about 4000rpm. Just fix the dang thing before that.
It doesn't even take baling wire to fix just patience and the resolve to do so.

Re: How Much Secondary Leakage?
 

91= 2.5 min.
93= 45 sec.

Re: How Much Secondary Leakage?
 

WOW! 2.5 min is the top score so far. She's tight!!!
I get 66seconds on mine.

Re: How Much Secondary Leakage?
 

Marc, just went thru the system when I had it up for the 510 package :dancing

Re: How Much Secondary Leakage?
 

Pump runs one second every five. Have a new vacuum solenoid and MSD coils to install this week. New left side oxygen sensor yesterday as i moved it from right to left and the code followed. Rear tires are bald and the washer fluid is full.

Re: How Much Secondary Leakage?
 

Interesting stuff! Thanks for taking it a step farther and starting this thread, Scott!

Re: How Much Secondary Leakage?
 

It's good to get things documented. When a reference is made to "average" ZR-1 then we know what's what.

Re: How Much Secondary Leakage?
 

I just recalled that the source of the leakage on mine was a real slow seepage out of the mini vacuum tank. This was a couple years back when I was testing the tubes with a handheld vacuum pump. It totally doesn't matter as the pump sucks air way faster than anything could possibly leak out besides a torn diaphragm.

I guess if my pump turned on every 5 seconds, I'd try to improve that, but otherwise it is just an academic discussion.

Re: How Much Secondary Leakage?
 

Since I ripped & kludged [sp?] 'em out, I won't vote (just for you there Scott ;) ).

But I had timed mine to 1-2 sec's every 12-15 sec's, when I posted up about it...

Re: How Much Secondary Leakage?
 

I try not to use terms like "kludge" and "ripped" out anymore. Some people find them upsetting and/or condescending along with "rattle can" and "wonky" :p
It's a "kinder gentler" world. :icon_scra
(click on each word for a deffinition)

Re: How Much Secondary Leakage?
 

So far the average (leakage) time between cycles would seem to be greater than 5sec, much greater.

Re: How Much Secondary Leakage?
 

moderator:
sorry i screwed it up.. i voted for greater than 30 seconds..in fact my pump runs(i stopped timing it after 60 seconds)

Re: How Much Secondary Leakage?
 

> 30 sec would include 60+ I would think. In any case you have a significant leak that requires attention.

Using a Mitivac (hand vacuum pump) one can isolate the problem fairly simply.

Here's a schematic of a 90, but the other years are quite similar, except the MAP switch is located under the ECM on the 90, but is under the plenum on 91+ cars.

http://i185.photobucket.com/albums/x...tsLT5Large.jpg

The place to start is with the rubber connector on the plastic vacuum line, located on the plastic line, just as the line goes under the plenum. Pull it apart and put your thumb over the end of the tube. If the vacuum pump shuts off, then the problem is under the plenum (sorry). Otherwise the pump itself or the tubing or check valve is suspect.

Once under the plenum, you can use a Mitivac to apply vacuum and proceed to "divide and conquer" until the leaking component(s) are isolated.

The plastic vacuum line I've seen packaged in rolls at AutoZone. It can be cut to length and shaped with a heat gun or possibly a hair drier. Rubber connectors can be had in generic form as well as vacuum solenoid switches.

Stopping here, because this is OT. But, begin another thread (if you haven't already) and we can help ya isolate the issue, if need be.

P.

Re: How Much Secondary Leakage?
 

Haven't voted yet and not sure if I should add this to this thread but, what's the difference in the way the vacuum pump should run with key on engine off or key on engine on? The reason I ask is I just went out this morning, turned the key on engine cold. Pump runs and doesn't stop. Started the engine and let it run for close to 10 minutes and the pump never came on (but does come on when I disconnect the vacuum line). Turned off the engine and immediately turned the key back on and now the pump is on off on off on off constantly.

Drives great all the way up to the limiter. Just wondering what the difference in engine on and engine off when it comes to the vacuum.

1995, #297. Stock except Corsas.

Re: How Much Secondary Leakage?
 

You will see Vacuum Check Valve #15 in Paul's post (this diagram is for a 1990 ZR-1) which lets Plenum Vacuum take over when engine is idling and Plenum Vacuum is high. Vacuum pump takes over when engine has wide open throttle and Plenum Vacuum is lower. Cruise Control and HVAC on passenger side of Plenum and Secondary Vacuum on Drivers side of Plenum.

Secondary Vacuum System for a 1990 ZR-1.
http://i185.photobucket.com/albums/x...tsLT5Large.jpg

1. In your case you had High Plenum Vacuum at idle for 10 minutes (so vacuum pump remained off).
2. Pump came on when you disconnected vacuum line cutting off Plenum Vacuum to the pump.
3. With Key on and No Plenum Vacuum, Pump will cycle maintaining Secondary Vacuum as it is suppose to do. The more often the vacuum pump cycles the indication of more vacuum leaks present.
4. Pump cycling on and off every minute indicates minimal Vacuum Leaks under the Plenum. Pump cycling on and off every 5 seconds indicates Vacuum Leaks under the Plenum (Secondaries will remain operational as pump can keep up with the leaks if it cycles off no matter the cycle time).

When you first turned the key on and Vacuum Pump ran constantly......that might indicate the check valve #15 was stuck open or leaking and the pump could not build up vacuum because it was sucking air from the plenum.
Or....that might indicate with engine cold the vacuum leaks are unacceptable and with engine warmed up the Vacuum Leaks under the Plenum are significantly less (vacuum lines/connectors swell up closing down some vacuum leaks).

Re: How Much Secondary Leakage?
 

Running out to the garage now to check mine.

Re: How Much Secondary Leakage?
 

I unplugged from the passenger side where the tube goes into the plenum and capped it : 1:55 seconds before my fingers got tired. Plugged in.. 6 seconds and on for about about 1.

Re: How Much Secondary Leakage?
 

Will have to do some digging around now. Later the same day I was finally able to get into an open enough stretch of road to open her up, ran all the way up to 7k like usual. I've got the FSM so obvious I need to do some homework on this part.

Re: How Much Secondary Leakage?
 

Passenger side is HVAC and Cruise.....I am confused....is that one minute 55 seconds.....whatever you capped on the passenger side...that has nothing to do with the secondary vacuum system.

It sounds like you are saying when you turn the key on (engine off) your vacuum pump is on for 1 second and off for 6 seconds which means you have vacuum leaks but are still functional on secondaries.

It would require you to start at the pump vacuum lines and work rearward to and under the plenum checking to see where that vacuum leak is located. Just unplug connectors and hold finger over side of connection coming from the Vacuum Pump. If Vacuum Pump quits cycling, the leak is beyond that point. If Vacuum Pump continues to cycle, leak is between that point and the Vacuum Pump.

I appears that both of you have functional Secondaries which you can very easily check with engine off and key on........

See Secondary Functional Test and Reconditioning the Secondary Actuators

Re: How Much Secondary Leakage?
 

8 minutes!! Do I win something? Lol! 1990 with over 120000 on it. Had the plenum off for injectors and was going to tie open secondaries but thought if the system is that tight I?ll leave them active for now. Was shocked it was that tight as the car in not overly clean.

Re: How Much Secondary Leakage?
 

Your prize is a Functional Full Power Switch :thumbsup:
I have several posts within my signature related to upgrading/replacing the original vacuum lines and rubber connectors (which have hardened and shrunk with age) under the plenum :cheers:

I do these inexpensive replacements on all Zs as part of the Top End Restorations :dancing

Re: How Much Secondary Leakage?
 

This is a great discussion as I have leak and my pump runs for 2 seconds and turns off for 2 second and then back on again. As of now I have no issue with secondary's. I find this odd but its the truth. I took it out for a 10 mile run with a ton of WOT and I had no codes or loss of power. What am I missing?

Re: How Much Secondary Leakage?
 

You're not missing anything. According to Maestro Haibeck the secondaries will work fine even if the pump cycles off for only 1 second.

http://www.zr1specialist.com/HAT%20W...%20Working.pdf

Re: How Much Secondary Leakage?
 

Yes agreed! Mine cycles off for about 2 seconds with no issues. I don't know if this question has come up yet but at how many seconds will secondary's stop working and then **** starts to shut down with the secondary's??? I would love to know to then trigger a plenum a removal!

thanks

Re: How Much Secondary Leakage?
 

We are having a Wazoo maintenance day this Sunday Nov 14. Jim has posted in Mid-Atlantic section of the forum. Come on down!