Pulling the Plenum for the first time...
 

I have had the ZR1 for a few weeks now and have driven more than I thought I would over these past few weeks. The no radio hasn't bothered me that much since I have some way of listening to tunes(phone with bluetooth speaker).

I have cleaned the grounds inside the car, but I know I need to clean the grounds on the engine block and anywhere else in the engine bay. I have been told that pulling the plenum is the right of passage to owning these cars.

I'm not a noob to working on cars in general, just corvettes. I have a guy local to me who went and looked over the car with me, let me know what I should do to get the car up to snuff. Pulling the plenum is on the top of this list to me.

List of things to do:
-Replace Fuel Injectors(don't know if its ever been done, but Tech 1 showed a big difference between the 2 banks of the engine)
-Fix some vacuum lines
-Change/flush coolant
-Change PCV rubber pieces
-Change MAP sensor hose(mine is all rubber not the hard plastic line like stock)

Is there anything I am really missing when pulling the plenum? Can I get some of these vacuum lines at the local part store? That MAP sensor hose is like $45 on Jerry's gasket. He told me to make sure I book about 8 hours to do all this work.

Re: Pulling the Plenum for the first time...
 

I will be watching this thread, as this is something I may be doing over the winter. There is a wealth of info on this forum, these guys really know the ZR-1 inside and out. I am always learnng something new on this site, and learning more about my 94 as time goes on.
Be sure to take pics along the way, as it is always good to get another look at what owners are doing to their Z's.
BTW, what year is yours? And good luck!!!

Re: Pulling the Plenum for the first time...
 

My car is a 1991. White with red interior.

I figured I would post this question on here in order to have all the parts lined out before I start tearing it apart.

Re: Pulling the Plenum for the first time...
 

I didn't know this thing either when I started (still don't much http://www.zr1.net/forum/images/icons/icon10.gif ); but maybe put every bolt back in it's hole when the part is out of the way, which takes longer, BUT, bolts NEVER get mixed up when you do.

And, clean the parts as soon as you remove them.

Dirty parts stack up REAL quick; then at re-assembly, you get rushed, and don't do as good a job as you'd have done otherwise.

And no one gets mad if you post LOTS of snappics as you go ;)

Re: Pulling the Plenum for the first time...
 

Billy,

Just a couple of suggestions.

1. The BLM split between left and right banks is not unusual particularly at low airflow levels like idle. If you are going to swap out injectors, it should not be because of that alone. If you suspect something else fine. Also, depends on mileage.

2. If stock coils and wires then I would upgrade these.

3. You'll need to make sure you drain coolant to levels below plenum.

Re: Pulling the Plenum for the first time...
 

When ignition is in run position how frequently and for how long does your vacuum motor run? If it stays quiet for 30 seconds or more I would say your vacuum lines are in good shape.
Also, I would have a couple of 3 way vacuum check valves handy just in case.
I would check all vacuum line plastic to rubber boot connections and if they are sliding relative to the other, I would slide the hard line out about a 1/4", dab of Crazy glue, slide back in. Also, seal the rubber boot shoulder with black silicone sealant followed by a zip-tie. 'Course all that is unnecessary on my car since I pulled the whole secondary vacuum off the motor now.

Re: Pulling the Plenum for the first time...
 

My car has 69,000 miles and to my knowledge has never had the injectors done. The car runs a little rough at idle. The local guy seemed to think it ran really rough for a ZR1.

They appear to be stock coils, and wires. It seems to be hit or miss with changing out coils.

I would like to replace vacuum lines not just put a band aid on them. Where should I get the 3 way vacuum check valves?
My vacuum pump runs every second or so. So it there are some vacuum leaks.

Re: Pulling the Plenum for the first time...
 

Based on my experience, unless plastic lines are cracked and broken, replacing with new lines will only buy you time because heat and oil fume softens the rubber and makes the seal loose. Crazy glue, zip tie and sealant (or epoxy) on the shoulder is the permanent solution.

http://www.amazon.com/ACDelco-15-505.../dp/B0016I0E42

Re: Pulling the Plenum for the first time...
 

Took me 3 hours to pull the plenum off a motor last night. Anytime I do something the first time I make or have diagrams and try to follow the service manual steps.

The throttle body extension is real fun getting off when attached to the engine. 25t 1/4 ext and fish

Re: Pulling the Plenum for the first time...
 

Not necessarily vac leaks...

It could be air getting by the 2' TB butterfly (which I suppose amounts comparably to a vac leak), but not entirely the same.

Cut a gasket withOUT cutting the 2' holes, to re-check idle quality. I did this, and idle was rock-steady. I'll put it back in, when I learn coding.

Re: Pulling the Plenum for the first time...
 

A properly running ZR1 will easily pass the "Nickel Test".

http://www.digitalcorvettes.com/corv...o/1413/cat/508

'Crabs

Re: Pulling the Plenum for the first time...
 

What would this prove? If it does prove anything how can it be fixed?

Re: Pulling the Plenum for the first time...
 

For starters, it can show that you have no vacuum leaks ELSEwhere, and that you have everything ELSE in perfect tune order.

Did in my case anyway.

Fix? None yet...

Re: Pulling the Plenum for the first time...
 

What are the PCV rubber pieces part numbers? Will Jerry's Gasket be the best place to get these kinds of pieces?

Re: Pulling the Plenum for the first time...
 

Re: Pulling the Plenum for the first time...
 

See if these are the PCV rubber parts you want to replace.

http://jerrysgaskets.com/store2/root...e91f10f4ed35c7

http://jerrysgaskets.com/store2/root...roducts_id=854

http://jerrysgaskets.com/store2/root...roducts_id=855

http://jerrysgaskets.com/store2/root...roducts_id=278

Re: Pulling the Plenum for the first time...
 

Jerry is Da Man!

Re: Pulling the Plenum for the first time...
 

Looks like that last one is what I'm looking for. I think mine is leaking just a wee bit. Better replace that now rather than later.

Looks like the parts list is growing. Who know Corvette parts were as expensive or more than Porsche parts...

My wife is rolling her eyes now for encouraging me to pick up this beast. I have a torn apart motorcycle in my garage and now the ZR1 has taken over my "project focus".

Re: Pulling the Plenum for the first time...
 

What is the best place for vacuum lines and rubber fittings?

Do Vitton gaskets really make a big difference over Buna gaskets? Can o-rings be sourced at the local auto parts store or are they specific to the ZR1?

Re: Pulling the Plenum for the first time...
 

Buna and Viton are oring materials not gaskets. There are better than viton also, and real cheap. Just get the oring number and order them from Applied Industrial Tech. or take one in and they will match explain the diferences, and order for you.

Re: Pulling the Plenum for the first time...
 

So the intake manifold gaskets are the same regardless?

The o-ring's are either ethanol compatible or not? Does anyone have the sizes for the o-rings required? I thought new fuel injectors come with the the o-rings required?

I am looking at getting the Accel Fuel Injectors. In the past when I purchased new injectors they came with the little orings already in place. I need to have all the parts ordered before I start this project. I don't want to be waiting on parts.

Re: Pulling the Plenum for the first time...
 

The man with all your gasket and answers to misc parts involved in your swap is Jerry Downy at JERRY'S GASKETS.

Re: Pulling the Plenum for the first time...
 

Knowing that major manufacturers use the lowest cost part that meets specs and mark it up as much as possible, when I buy parts I research who makes the OEM stuff and then which manufacturer makes the very best part, then I search for pricing.

When I use orings I most likely will use those that can handle nitromethane, the very highest in quality, as long lasting as available, and 2 floors (not steps) above those required in specs.

Gasket materials are all over the place also, I use solid copper gaskets on exhaust anytime I am able to and use a manufacturer that uses the same specs from the Chesterson 140 gasket material or make my own.

I only like to do things once, so I will pay more for the parts and components or make them to make sure of it.


Jerrys has the gaskets/orings and so do other sources.

Re: Pulling the Plenum for the first time...
 

Has anyone ever made their own map hose? Is it recommended to replace the spider of vacuum hoses with all soft flexible ones like silicone?

Re: Pulling the Plenum for the first time...
 

I made my own map hose w/ 1/4" hard plastic hose and rubber hose from Advance Auto. You don't want to use soft flexible hose for vacuum. Vacuum will make them collapse and inoperable.

Re: Pulling the Plenum for the first time...
 

Parts have been ordered. I told the wife I ordered parts, but didn't tell her the total amount...

Please god don't let her see the CC bill.

Re: Pulling the Plenum for the first time...
 

When I did my exhaust, she asked how much? I said about the same as the new couch you're looking at. I had to wait. Don't buy Lazy Boy buy the way.

Re: Pulling the Plenum for the first time...
 

On my 944 Turbo I used all silicone tubing for the vacuum lines. It worked great. They were oil resistant and everything.

Re: Pulling the Plenum for the first time...
 

You may want to check with Eaton Aeroquip for hoses, they have every kind and size that will take anything you put into them.

Re: Pulling the Plenum for the first time...
 

Now the fun starts...

Marq21 and I pulled the plenum on the ZR1 yesterday. Need to give him a shot out for helping me out on this job. Without him I would have not been able to fix the secondaries issue I was having, or get the complete job done.

First off, WOW. The car runs completely different. I don't even know what to say. If your car doesn't surprise you every time you hit the gas WOT, then you need to get some service done.

My car is having an intermittent high idle issue. It doesn't sit at the prescribed 750 RPM. It idles around 900 rpm normally, and occasionally after coming to a stop will be at 1200 RPM. With a Tech 1 hooked up the IAC shows 0. It occasionally would move, but at idle it was 0.

I have read there is IAC re-learning procedure that can be done. The battery was unhooked for a few hours. I have the FSM, but I don't know the correct search terms to find it.

-Vacuum leaks were fixed
-Plenum gaskets were in good shape so they were re-used
-Accell Injectors were installed
-Check Valve replaced for cruise
-PCV Breather hoses in the valley were replaced
-New MAP hose

The car runs great throughout the RPM's now. It drives great, except idle is a little weird. In between gears the idle will kind of hang around 1500 RPM.

Re: Pulling the Plenum for the first time...
 

I forgot to post a few pictures. I should have taken more, but we were trying to get things done.

http://i856.photobucket.com/albums/a...psbabkai5a.jpg

Oil vapors were being vented to the atmosphere. I don't understand how this car ran at all.

http://i856.photobucket.com/albums/a...pso0vgo1ef.jpg

In this picture you will see a mouse nests. Guess what? There was a crispy dead mouse still in there. Surprisingly there are no chewed wires.

http://i856.photobucket.com/albums/a...psofmefmwu.jpg

Re: Pulling the Plenum for the first time...
 

Sounds like the High Idle Coast-Down issue, for which there was a GM TSB. Marc H has the chip code solution...

You might ALSO have air getting by the TB 2' butterflies, as I mentioned above.

Mouse needs butter (he's toast) http://www.zr1.net/forum/images/icons/icon10.gif

Re: Pulling the Plenum for the first time...
 

I didn't remove the TB at all, also I didn't clean the inside of the plenum at all.

Re: Pulling the Plenum for the first time...
 

Did you remove the throttle cable?

Re: Pulling the Plenum for the first time...
 

Yes I did remove the throttle cables.

Re: Pulling the Plenum for the first time...
 

Did it idle properly at 750rpm before you did the work?

Re: Pulling the Plenum for the first time...
 

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?

Re: Pulling the Plenum for the first time...
 

I doubt that its the TPS or IAC, if they were not removed. I am more inclined towards a vacuum leak associated with the work that was done. Its not unusual to have a cracked hose or leaking connection when re-installing the plenum. It's a little tricky keeping it all connected. You should backtrack your work.

Re: Pulling the Plenum for the first time...
 

Is there anyway to check this without pulling the plenum again?

Re: Pulling the Plenum for the first time...
 

take the intake bellows off and take a stiff box cardboard piece (like real stiff) or a phone book etc and block the air horn to see if you can stall it. An open tube will be audible enough if the engine is still running at that point.