Red89'-L98

I am going to take this on tomorrow and was wondering what the procedure for doing it is. I know to take off the throttle body and set it somewhat to the side and leave everything attached.

Then, take off the throttle cable bracket (Will I need to reset TV cable and such?)

Take out plenum to runner bolts and remove plenum. Along with various things that hook up to it.

After, replace EGR valve. When replacing the valve should I put any kind of stuff on the gasket such as RTV or some kind of Never Seize product?

Replace vacuum lines while I am in there.

When reassembling, I plan on using new upper gaskets for the runners and new gasket for the throttle body. Should I put any kind of RTV or never Seize on those?

Finish assembly and test.

If you see anything that I may have missed please let me know or if you know any good tricks that may help move the process along easier.

Thanks, Stephen

WW7

You have the procedure pretty close above...The only thing I do differently is I don't remove the throttle body,I just unhook the lines, but if your going to replace the gasket it does need to be removed...The runners are at an angle so you can just sit the plenum back down in and tighten it up.. What I do is use some of the spray gasket adhesive on one side of the plenum gaskets to hold them in place when installing the plenum, this stops them from moving when sliding it down between the runners.There's no need to loosen the runners either, some guys do but it's not necessary. Also use antiseize on the plenum and TB bolts, I use antiseize anytime Im putting bolts into aluminum..You don't need anything on the egr gasket unless you want to use some of the spray on adhesive, same as you use on the plenum gasket.No need to reset the TV cable, just hook it back up.......Good Luck.....WW

Red89'-L98

Thank you very much.

I am now planning on removing the throttle body completely now that I think about it, it has been about 3 years since I cleaned it thoroughly.

Also yes, I completely forgot about the anti-seize, so thanks for reminding me about it.

Again, thanks

WW7

One more thing I thought of... I don't use a torque wrench when tightening the plenum bolts, I have seen to many stripped bolts because of using a torque wrench on these small bolts...I just tighten them with a socket to where I think they should be . They're only sealing air, so if they would leak you can just crank down on them a little more, which is better then having to use a helicoil to repair the stripped threads....WW

Red89'-L98

So a torque wrench is a bad idea? I have a torque wrench and was gonna use it but set it to a few pounds lower than what it said for safety measure.

Only bad thing is I don't know when enough would be enough haha I think Ill start out by hand and get them just past hand tight and if it leaks then ill start tightening it little at a time from there.

WW7

The problem with a torque wrench on these bolts is, these bolts have probably been removed many times in most of these cars in there lifetime.( 25 years). Once you remove bolts so many times, the aluminum threads get worn and become thinner then when new ( thinner and weaker) ...Then we come along with a torque wrench and apply the pressure to them that is meant for new threads, and we end up pulling out the old threads and stripping them to where we have to use a helicoil...Since all they are sealing is air , the best way to seal them is to only apply the pressure needed to seal them completely, no more......WW

Red89'-L98

I can honestly say that I didnt think about it that way. Thats something I will now remember for a long time to come.

Im going with your advice for sure and just doing it by hand. Much safer and it is just air that your sealing so it will be just fine.

Thanks again

65Z01

Copla things:
-never use silicone (like RTV) near an air intake surface as it fouls up the O2 sensor.
-the plenum-runner gaskets have prongs that plug into the Al to hold them in place during reassembly.
-use care when handling the hard vac lines like those under the TB to avoid breakage.
-no adhesive is needed on the TB-plenum gasket as the bolts will hold it in position.
-use a good tight socket on the EGR bolts as they round off easily and then off comes the runners to access them. A little PB Blaster wouldn't hurt either.

Red89'-L98

Thanks for the tips, do you know if the brake booster vac line do i just pop off the rubber line from the metal or should I just unscrew it at the plenum?



Also, I was driving it on the highway today because I needed to or I wouldn't have, but it set off the code 45 and code 32 at the same time, so does that mean the EGR valve is what is causing my rich condition also?

I am figuring it does but want to make sure to see if I have to look into something else as that problem.

Thanks for all the help everyone.

65Z01

The code 45 == O2 sensor rich condition.
This can be caused by a bad TPS, bad MAF, full purge canister and such.

Joe C

sorry WW, here's one point that I have to disagree. I've been wrenching on L98 tuned ports for almost 20 years now, and have never encountered a stripped bolt by using a torque wrench. I'm a big proponent of the torque wrench, especially anything going into aluminum.

if used properly, using a torque wrench, and "torque to spec," is NEVER a bad idea.

WW7

Joe, I guess we'll just have to agree to disagree then, which is ok.....As long as the aluminum threads are fairly new and not worn, a torque wrench is not a problem...I personally have stripped a few bolts going into aluminum with a torque wrench, and have seen a few done by others...Like I explained above, once the threads get worn from many uses, (like in 25 year old cars), the bolt is sometimes slightly loose in the threads to start with,the threads aren't as strong as when new because of wear, and sometimes torquing to spec can pull the threads out...This has been my experience..I do always use a torque wrench on the larger bolts like on the manifold to head, which have to be torqued to spec to be effective...WW

Joe C

no problem

WW7

I thought I was the only one that got up this early.....WW

tunedport85inject

What can do a man early in the morning?.... Post on Corvette Forum...😄😄
Btw where i am now are 3 pm...😄

Red89'-L98

Yeah, I got to get in depth and see what it is cause the code will come on for about 10-15 seconds of highway driving and then just go away without even having to shut off the vehicle. I am gonna start with check the fuel system on that part.

I will be receiving the new EGR valve and some other parts to replace by Friday and should be done by saturday.

I wish they made a car with all one size vacuum line cause I cant find some of the lines in bigger sizes for the life of me, might have to find a gas company nearby and see if they have any.

Then there is smaller line with bigger connectors on them, I dont know if to replace with line the size of the connector or with a new line of the smaller size and the old connector.

Anyway, thanks for all the help, and it should be a breeze to get through this.

mtwoolford

try to obtain an INCH pound wrench and be gentle

Joe C

torque is torque, no matter how it's applied - 120 in.lbs is the same as 10 ft.lbs. -

WW7

Dat be True......There's always Helicoils for the problems that may arise...Everyone should have to install a Helicoil at least once in there life, just so they know how it's done...It's all good......WW

Joe C