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Old 10-06-2014   #41
Schrade
 
Join Date: Dec 2012
Location: NC
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by Billy Mild View Post
In general the car didn't run very well before this work. But it did have a consistent idle.

Now the car runs better, much better, but the idle is not consistent. As far as I can tell there aren't any vacuum leaks. I tried spraying potential vacuum leaks with WD40.there was 0 change.

Could be TPS or IAC possibly?
You boosted RPM's before spraying for a leak?

Quote:
Originally Posted by Schrade View Post
FIRST (fully warmed up motor); block the gas pedal, or block the throttle linkage. YOU HAVE TO DO THIS TO GET A STEADY IDLE , around 1,250 rpms, or a little higher. If you don't, you can fish starting fluid, a propane hose, or WD40, or Krylon, or hair spray, or pee, anything, until you need a sweater in Hades, but if the motor is lopin' idle already from a vacuum leak, you ain't gonna' find any leak, unless it's so big that Little Jack Horner can stick his thumb in it and pull out a pineapple NOPE.

AFTER you get a steady idle, THEN, you can spray starting fluid everywhere - that's the best detector, because it's vapor pressure is very high - a LITTLE at a time, all around the motor, until you get the rpm SURGE. Follow the vacuum lines to the EVAP cannister too. You might even have to follow the EVAP lines from the EVAP cannister to the gas tank too, but that vacuum leak will show up as a DTC 32 EGR fault, and won't normally show as loping idle, unless the EVAP cannister has been by-passed (been there, saw that uh-HUH yup).

If you get a surge in a tight spot, and can't tell exactly where it is, light a book of matches, blow out the match heads while they're still burnin', and feed the smoke to the tight spot to see it get drawn in.

Fear not the starting fluid; you cannot put the can down fast enough and light the matches fast enough to catch the starting fluid, because the vapor pressure is so high.
Short of that, the phone book trick like mike100 said worked for me @ TE Cleanup. I had forgotten to put a clamp on the PCV's rubber valve cap-to-pipe connection, behind plenum, and it was sucking air.

After that, it was ROCK steady 675 (with the TB 2' gasket block, which told me that all else was in perfect tune order).
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I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads...

( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b]

Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc...

1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3"

[IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]

Last edited by Schrade; 10-06-2014 at 10:04 AM.
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Old 10-06-2014   #42
XfireZ51
 
Join Date: May 2007
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Default Re: Pulling the Plenum for the first time...

The LT-5 sucks so well at idle that it doesn't take much to have a vacuum leak.
How often does your secondary throttle vacuum pump come on w key ON?
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Old 10-06-2014   #43
Billy Mild
 
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by XfireZ51 View Post
The LT-5 sucks so well at idle that it doesn't take much to have a vacuum leak.
How often does your secondary throttle vacuum pump come on w key ON?
My vacuum pump runs for literally 1 second then shuts off. The system appears to be pretty tight as far as that goes. It doesn't seem to leak from that aspect. Everything was ZIP-Tied and and any pieces that didn't seal well with a vacuum pump were replaced.

I have leaking fuel from under my plenum. It didn't do this the night I got the work complete, and it didn't leak yesterday. It must have done this overnight. So I guess the plenum is coming back off?
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Old 10-06-2014   #44
XfireZ51
 
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by Billy Mild View Post
My vacuum pump runs for literally 1 second then shuts off. The system appears to be pretty tight as far as that goes. It doesn't seem to leak from that aspect. Everything was ZIP-Tied and and any pieces that didn't seal well with a vacuum pump were replaced.

I have leaking fuel from under my plenum. It didn't do this the night I got the work complete, and it didn't leak yesterday. It must have done this overnight. So I guess the plenum is coming back off?
BTW, the injector O-rings, if not seated properly, can be a cause of a vacuum leak. Were they removed earlier? Good idea to use some sealer where the injector O ring seats in the housing.
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Former ZR-1 Registry - BOD
1972 Corvette 4speed base Coupe SOLD long time ago
1984 Corvette Z-51/4+3 SOLD
1992 Corvette ZR-1 Aqua/Gray #474 SOLD
1992 Corvette ZR-1 Black Rose/Cognac #458
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Old 10-07-2014   #45
Billy Mild
 
Join Date: Aug 2014
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by XfireZ51 View Post
BTW, the injector O-rings, if not seated properly, can be a cause of a vacuum leak. Were they removed earlier? Good idea to use some sealer where the injector O ring seats in the housing.
I replaced the injectors and all the associated o rings with brand new ones. It appears the one injector o-ring got pinched which caused a decent sized fuel leak. The only thing that was weird is it just started to leak Sunday night. All this work was performed on Saturday evening. I have remedied this leak. I also used 2 stroke oil when I put the fuel rails back in.

I am working through getting everything that would possibly leak air ziptied very tight.
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Old 10-07-2014   #46
Billy Mild
 
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Default Re: Pulling the Plenum for the first time...

I put the intake back on. The car sometimes hunts for an idle. Going up and down just llittle bit. Everything is ziptied tight or clamped down.

Should I try blocking the intake port with some cardboard?

In unrelated news I didn't have the coolant hose to the intake manifold tight and it sprayed coolant everywhere. Whats the best way to clean that up?
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Last edited by Billy Mild; 10-07-2014 at 11:52 PM.
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Old 10-07-2014   #47
Schrade
 
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by Billy Mild View Post
I replaced the injectors and all the associated o rings with brand new ones. It appears the one injector o-ring got pinched which caused a decent sized fuel leak. The only thing that was weird is it just started to leak Sunday night. All this work was performed on Saturday evening. I have remedied this leak. I also used 2 stroke oil when I put the fuel rails back in.

I am working through getting everything that would possibly leak air ziptied very tight.
Been there done that.

Dropped a socket (ask Paul W on the particulars), and had to pull the INJ / rails. Gas dried a lubed O-ring, and it sheared off nice and clean on rail re-install. Fuel LEAK!!! And AFTER one successful FP test GRRR

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I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads...

( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b]

Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc...

1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3"

[IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]
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Old 10-08-2014   #48
Billy Mild
 
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by Schrade View Post
Been there done that.

Dropped a socket (ask Paul W on the particulars), and had to pull the INJ / rails. Gas dried a lubed O-ring, and it sheared off nice and clean on rail re-install. Fuel LEAK!!! And AFTER one successful FP test GRRR

Almost exactly what he failed ORing looked like. I was pissed. Thing is the leak didn't show up until a 36 hours later.

So I drove the car this morning, look like my coolant tank is leaking just a wee bit. Need to put some more JB weld on it again. Other than that the car ran smooth. Before the car was fully warmed up the idle would go up a little bit and back down.

I drove on the highway for about 20 minutes and then the idle was rock solid when at a complete stop. If the car was rolling at all the idle would be increased to 1,300 RPM.
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Old 10-08-2014   #49
mike100
 
Join Date: Feb 2011
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Default Re: Pulling the Plenum for the first time...

Don't think you are the only one that has had to go back in right after a plenum pull. Ha! I fixed my vacuum leak, cleaned everything up, and then really had a chance to start driving mine just to discover that my injectors were going out if you drove it for more than 20 minutes! I pulled it off the very next day.

Always buy a second set of gaskets to have in 'stock'.
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Old 10-08-2014   #50
Schrade
 
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Default Re: Pulling the Plenum for the first time...

Quote:
Originally Posted by Billy Mild View Post
Almost exactly what he failed ORing looked like. I was pissed. Thing is the leak didn't show up until a 36 hours later.

So I drove the car this morning, look like my coolant tank is leaking just a wee bit. Need to put some more JB weld on it again. Other than that the car ran smooth. Before the car was fully warmed up the idle would go up a little bit and back down.
If it was wobbly idle also at Closed Loop, I'd say 2nd TB leak, but if smooth @ CL, you're probably fine.

[/QUOTE]I drove on the highway for about 20 minutes and then the idle was rock solid when at a complete stop. If the car was rolling at all the idle would be increased to 1,300 RPM.[/QUOTE]That is high idle coast down issue - betcha. You gotta' get the memory / calibration module re-coded.
__________________
I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads...

( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b]

Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc...

1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3"

[IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]
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