aggravation

I want to be sure no air is able to be sucked past the O rings due to the powder coating around those holes. I was hoping there is a way to test this possibility without removing the fuel rails so I was thinking if loaded something like Silglyde into a syringe so I could squirt it down into the space above the O rings then drive the car a bit and see if it stays there or not...

The problem is I don't know what to expect from the Silglyde if it doesn't get sucked past the O ring...will it remain thick and visible or will the heat and vibration disperse it enough to where I end up thinking it got sucked past the O ring!
And if it does get sucked in there will it cause a problem?

I used Silglyde to lube the O rings when I put them in there but just looking at them now it's hard to tell if there is any residue left or not.

Please no JB Weld or Duct Tape jokes

worf928

Craig, can you pressurize the intake per the WSM? If so, a leaking injector o-ring can be found using this method. See https://rennlist.com/forums/6005793-post5.html

As to how to seal them.... no idea.

But, if you've got the right-sized lower o-rings in a stock intake then I think you should be ok unless something's damaged. I've yet to find a leaking injector o-ring on a stock S4 intake - powdered or not - if the o-rings were new and properly seated into the bores.

Bill Ball

Don't use Silglyde. I have very lightly lubed those o-rings with it, but bigger quantities could foul your O2 sensor.

If you are checking for leaks, squirting carb cleaner, WD-40 or similar around the injectors on an idling engine should reveal a leak by raising the idle briefly after a squirt.

ZEUS+

Silicone can damage an 02 sensor. Find a shop with a smoke machine and have it smoked. Bill beat me to it.

Landseer

Just for reference,
Fourth paragraph from the end of this article on O2 sensors references possible silicone damage.

http://www.picoauto.com/applications/lambda-sensor.html

ZEUS+

There is a trick for sealing. It would be better to replace the seals, but if you dont want to disassemble you can try this. I'm sure negative criticism will follow as usual.
This is an old trick for sealing oil leaks. Front and rear intake oil leaks are common with domestic V8's. Area of leak would be cleaned and dried. A vacuum cleaner would be secured to the oil fill. After a few minutes rtv is applied to area and sucked in. Preferably the right stuff works best.
You can clean and dry around injectors. Apply a thin bead of right stuff. Run engine for about thirty seconds. Let it cure completely. Will be more to clean next teardown, but it will seal.

aggravation

Thanks guys, I'm waiting on some new bearings for the flappy shaft so an intake R&R is coming up soon. I just was looking for a quick check in the meantime but it was probably a stupid idea...I'll just wait and examine the rings and surfaces once I pull the intake...for the fifth time in two months!

On the upside, the car is an absolute beast other than the high idle!

David L. Lutz

By the way, is you idle still at 1000 or above when up to temp.?

Garth S

A hand held propane tourch ( unlit, BTW ) is also effective for revealing leaks.

aggravation

Right now it is 900 as the high point when fully warmed up and sometimes when stopping at a traffic light it will drop to 800.
I cleaned all the electrical ground points and the power connections on the CE panel with a dremel tool and wire wheel, even pulled every fuse and cleaned them. Pulled quite a few connections loose on the back side of the CE panel and polished them as well.
After doing that I seem to have caused the engine to run smoother and the idle now stays at 900 tops instead of 1000.

I'm resolved at this point to find and stop all air leaks at the throttle plate and flappy shafts because after some more quality time with the SharkTuner and talking to John Speake it's becoming clear that the SharkTuner and my O2 loop are doing what they are supposed to do and it has to be false air causing the problem.

If I have to I'll be breaking out the Yamabond and sealing this bad boy up like King Tut!

Bill Ball

If you have the right o-rings and they went in snuggly like they should, but you still suspect a problem there, then one possibility that I have seen and mentioned is that an o-ring may not have seated properly. They can hang on the lip of the manifold and get pinched. I check for this visually right as I seat the injectors and rails and usually I can spot the hung o-ring, pull the rail back out and try again until they are all properly seated. It is possible that the hung portion can be to the inside and not be visible. Lube during injector insertion is the key. I used to use SilGlyde, but the potential for O2 sensor fouling caused me to change to a Teflon-like based lube called Super Lube synthetic multipurpose grease even though I had no problem, with SilGlyde. I avoid petroleum-based greases unless the o-rings are known to be oil-resistant.

Anyway, try the squirt solvent method or the propane Garth mentioned. Propane tends to flow/blow all over so may make it hard to isolate a problem if you find one, but I have used it successfully too. You may find a general problem, then use a more directed squirt of solvent to locate it.

Is this deja vu all over again? Didn't you test the manifold area before as Garth and I are suggesting and find some leaks that lead to a manifold rebuild?

aggravation

I never found anything conclusive testing while the intake was installed. So I pulled the intake and blocked off the bottom of the eight individual tubes and the injector holes, assembled the throttle body, ISV with hoses, MAF, boot, etc. etc.
Blocked off all vacuum lines and pressurized the whole assembly up to 15psi.
The only leak was a small bit at the throttle plate shaft and at the flappy bearings.
Those bearings were brand new from the intake R&R done the month before, the throttle plate shaft was never touched. Also the ISV is brand new and it has a small amount of air leaking from the end of it where the tubular body crimps to the end piece so I'll either get yet another one, use the old one or seal the new one....

I have some new bearings coming that have a seal on both sides and I'll tear the throttle plate shaft apart and replace whatever seals it as well.

The O ring experiment was just a long shot theory that I wanted to explore while I wait for the new bearings to arrive.

So deja vu...sort of...it's the perpetual pain...more like herpes without the sex

Larry928GTS

Did you check all of the various things that connect to the vacuum ports on the intake manifold while it's in the car? It could be a leak far away from the intake where the air is entering and going through the vacuum line all the way back to the engine. Something like a leak at your boost gauge, or maybe some vacuum operated part of the climate control could be allowing air into the system that eventually works back to the intake.

I'd try disconnecting each of the vacuum lines that connect to the intake and then connect them to something like a MityVac and see if they hold vacuum or not.

aggravation

With the engine running I had all the vacuum lines disconnected from the intake at one point and the ports and hoses all blocked off air tight. The idle was still high....