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-   -   Chasing down an air leak........ could it be? (http://www.camaro5.com/forums/showthread.php?t=150253)

PQ 05-31-2011 01:09 PM

Chasing down an air leak........ could it be?
 
Ok, I have to pull the maggie off for a third time. Looking for the same thing.

Drove to Atlanta this weekend to have Vengeance Racing tune the car. We were pretty sure the mis and surge was in the tune, and so I went up to have it re-tuned to stop doing it.

Well, he couldn't get the missfire/surge to go away. Couldn't find a leak. But he says there is one and that's why I'm having the problem.

Made the same dyno numbers as original but added 10 in torque. (470 rwhp - 480 tq) pretty much.

So the leak must just be at low rpm??? :iono:

At any rate; Somebody tell me what to look for. Most likely places to find a leak. Mike, at Vengeance, said the back side of the vacuum hose going into the heads (the one that goes into the rear of the driver side valve cover that the catch can connects to) is leaking. But that's not what the problem is because it didn't get better when we plug it off.

So I have a leak somewhere.

I've already done just about everything imagineable, but I'll just do it agian, again, again. I'm hesitant to spray carb cleaner by the headers, obviously, but I will. :laugh:

So, any suggestions as I go through this again.

You post it, I'll do it.

List of things I'm going to do already, I'll proceed to the next unless I find it.

1. Cut a 10mm socket down to fit the bolt under the rear drive pulley and get better torque on it.
2. Remove hoses and plug the hose stems completely. (If the miss goes away I know it's in the hoses)
3. Carefully spray carb cleaner around the manifold.
4. Remove the bloser and replace the gaskets.




OH, ya. Car runs like a beast when it's up in the band. But it's died 7 or 8 times now. Twice pulling out into traffic. Pissed a guy off pretty bad. He was laying on his horn. lol



UPDATE: Turns out it was a header gasket leak. Go figure.

anthonyj9h 05-31-2011 01:16 PM

water should help find it on a hose if its there, as far headers loosen and retighten and torque to spec...check the throttle body sometimes ppl miss things when tightening.... hmmmmmm the seals on your cai maybe?

PQ 05-31-2011 01:23 PM

Quote:

Originally Posted by anthonyj9h (Post 3283209)
water should help find it on a hose if its there, as far headers loosen and retighten and torque to spec...check the throttle body sometimes ppl miss things when tightening.... hmmmmmm the seals on your cai maybe?

Hoses are vacuum. So I'm not sure I wnat to do water. Carb cleaner maybe?

Headers have never been off. Not sure I want to do that. :iono:

I'll spray the intake all over with carb cleaner.

I'll retorque the TB too. When I pull the blower. I know everything has been torqued to spec when I installed it the second time, but the second bolt to the rear on the passenger side.

Thanks. I'll make sure to check those things. :thumbsup:

anthonyj9h 05-31-2011 01:26 PM

lol yes i know they are vaccum remove them and dunk in water to see if any air bubbles come up like you would on a tire, as far as your headers since they havnt been off check the gaskets for exhaust leaks too and then retorque....lots of vibration going on in that engine bay

CamaroSpike23 05-31-2011 01:31 PM

gotta be an exhaust leak.

anthonyj9h 05-31-2011 01:32 PM

i dont know if you took the heads off or not so i would say check those gaskets as well

PQ 05-31-2011 01:52 PM

Quote:

Originally Posted by anthonyj9h (Post 3283273)
i dont know if you took the heads off or not so i would say check those gaskets as well

Heads never came off. But at this point, I guess I could spray them too.

I just don't want to mess around spraying too much around the headers. lol

anthonyj9h 05-31-2011 01:53 PM

Quote:

Originally Posted by PQ (Post 3283393)
Heads never came off. But at this point, I guess I could spray them too.

I just don't want to mess around spraying too much around the headers. lol

lol awwww come on dont be shy:D

Dave Coyle 05-31-2011 02:02 PM

One thought that comes to mind for me is, have you thought about a "hair-line-crack" in the Maggie body? If you spray starter fluid around it you may find a crack but may not be able to "see" it. I you can not find the problem you may want to take the Maggie to a shop and have it magged for cracks, the mag process will find cracks where the eye can not! Good luck, sounds like you could use it!!!!

HufferSS 05-31-2011 02:05 PM

Doesn't Vengeance have a smoke machine they could use to diagnose? It not then I would suggest you find a local tech that might have one and knows how to use it.

You will track the vacuum leak down in no time.

anthonyj9h 05-31-2011 02:08 PM

try this as well....
Do a visual inspection. Check all of the under hood vacuum hoses, connectors and plastic lines for softening, collapsing and cracking. Pay particular attention to the PCV and evaporative emissions systems. The vapors in these two systems attack rubber, and are a common source of vacuum leaks. Replace any softened, deteriorated, or collapsed hoses and connectors. Big leaks can be identified by a tell-tale hiss. If no visual leaks are detected, move to the next step.



Slowly spray carb/intake cleaner around the intake manifold and throttle body, with the engine running. If the vacuum leak is one of these gaskets, the spray will restore the air-fuel ratio momentarily and the engine speed will change as a result. Go slowly and allow the engine speed to stabilize before moving to the next area. Any place that the spray causes a change in engine speed is the source of a vacuum leak. Avoid spraying the cleaner directly into the intake tract. This will give a false indication of a leak. If no leaks are found during this test, move to the next step.



Pinch each vacuum hose closed until the one that changes engine speed is found. Begin at the throttle body and eliminate them one by one, then move to any remaining vacuum trees (these are multi-ported vacuum tees that supply vacuum to more than one device) located on the manifold, firewall or fender well. Pay particular attention to the large vacuum hose attached to the brake booster. A sticking valve or ruptured diaphragm in the booster is a common vacuum leak source.
If no vacuum leak is found during this test, there are no vacuum leaks.

PQ 05-31-2011 02:39 PM

Quote:

Originally Posted by Dave Coyle (Post 3283448)
One thought that comes to mind for me is, have you thought about a "hair-line-crack" in the Maggie body? If you spray starter fluid around it you may find a crack but may not be able to "see" it. I you can not find the problem you may want to take the Maggie to a shop and have it magged for cracks, the mag process will find cracks where the eye can not! Good luck, sounds like you could use it!!!!

That is my worst fear. We've breifly discussed that.

Quote:

Originally Posted by HufferSS (Post 3283459)
Doesn't Vengeance have a smoke machine they could use to diagnose? It not then I would suggest you find a local tech that might have one and knows how to use it.

You will track the vacuum leak down in no time.

They might. I only dealt with the tuner. And they didn't have time to fool with it. Besides, I had just paid 600.00 to try with a tune.

But, if I end up pulling the maggie and doing all the work and I still have the leak, I'll go have that test done. Maybe I should try it before hand.

Quote:

Originally Posted by anthonyj9h (Post 3283468)
A sticking valve or ruptured diaphragm in the booster is a common vacuum leak source.

Discussed this too. Not sure how to test it. It encased so you can't really visually do it.

anthonyj9h 05-31-2011 02:42 PM

the smoker idea you should really take time to do good advice

hypurone 05-31-2011 02:59 PM

Quote:

Originally Posted by PQ (Post 3283612)
Discussed this too. Not sure how to test it. It encased so you can't really visually do it.

As simple as crimping shut the supply line to it at the manifold end...

HufferSS 05-31-2011 03:04 PM

Smoke machines were invented to stop stumbling around in the dark when it comes to vacuum and emissions leaks. If you CAN find it with a visual inspection or carb clean...then a smoke machine can find it in about 1% of the time that you would spend doing it the 1984 way.

:D

PQ 05-31-2011 03:12 PM

Quote:

Originally Posted by hypurone (Post 3283721)
As simple as crimping shut the supply line to it at the manifold end...

But the vacuum comes from that end. Wouldn't I need to do that from the other end? And how could I do it. I'd have to get behind the firewall right? :iono:

Quote:

Originally Posted by HufferSS (Post 3283737)
Smoke machines were invented to stop stumbling around in the dark when it comes to vacuum and emissions leaks. If you CAN find it with a visual inspection or carb clean...then a smoke machine can find it in about 1% of the time that you would spend doing it the 1984 way.

:D

I'll have to check that out. Any idea of a known shop?

HufferSS 05-31-2011 03:32 PM

Any shop worth a hoot will have a smoke machine.....look for one that has a reputation for working on more modern stuff or being a good diagnostic shop....but it's a pretty common tool for a commercial repair garage to have.

All it is a machine that literally creates smoke. You can plugin to your vacuum system and hit the button....watch for smoke. You can add dye and use lights etc to find tiny leaks....it's pretty cool tool.

PQ 05-31-2011 03:37 PM

Maybe I should start smoking again and use a cigarrete? :D

hypurone 05-31-2011 03:39 PM

Quote:

Originally Posted by PQ (Post 3283767)
But the vacuum comes from that end. Wouldn't I need to do that from the other end? And how could I do it. I'd have to get behind the firewall right? :iono:

No, the vacuum is generated at the intake manifold/maggie and fed to the booster via the line. You want to crimp it shut at the manifold end to eliminate the booster, line and check valve. If that identifies the prob, then you can work your way down the line to see what component is the prob. Capiche? :D

anthonyj9h 05-31-2011 03:40 PM

what he said sorry got a lil busy

PQ 05-31-2011 03:42 PM

Quote:

Originally Posted by hypurone (Post 3283904)
No, the vacuum is generated at the intake manifold/maggie and fed to the booster via the line. You want to crimp it shut at the manifold end to eliminate the booster, line and check valve. If that identifies the prob, then you can work your way down the line to see what component is the prob. Capiche? :D

So, if there is no change when I do that. Then it's NOT the check valve at the brake booster?

I took the hose OFF of the valve at the brake booster and plugged the hose with my finger. It was still missing. So I guess that's the same thing. :rolleyes:

hypurone 05-31-2011 03:46 PM

Quote:

Originally Posted by PQ (Post 3283921)
So, if there is no change when I do that. Then it's NOT the check valve at the brake booster?

I took the hose OFF of the valve at the brake booster and plugged the hose with my finger. It was still missing. So I guess that's the same thing. :rolleyes:

Sort of, you were downstream of the check valve so technically it could still be the problem... Crimp it upstream of the valve or remove the valve and plug the line to be sure.

PQ 05-31-2011 03:52 PM

Quote:

Originally Posted by hypurone (Post 3283950)
Sort of, you were downstream of the check valve so technically it could still be the problem... Crimp it upstream of the valve or remove the valve and plug the line to be sure.

The L99 doesn't have the canister. Only the fitting that plugs straight into the firewall. I suppose I could pull it out and plugg it from there, with my finger. That would work, but since I still have the problem plugging the hose at the blower, I guess I'm ok?

hypurone 05-31-2011 04:58 PM

Quote:

Originally Posted by PQ (Post 3283970)
The L99 doesn't have the canister. Only the fitting that plugs straight into the firewall. I suppose I could pull it out and plugg it from there, with my finger. That would work, but since I still have the problem plugging the hose at the blower, I guess I'm ok?

Yeah, sorry. I misread your post. If you disconnected the hose on the intake side of the check valve you should be good at that area then...

Speedy1975 05-31-2011 05:38 PM

Are you seeing any CEL codes? Typically with any VAC leak you'll get a CEL especially if it's bad enough to cause the engine to idle erratically.

Is it just a bad idle (erratic) or are you sure it's a true miss of the engine?

Did you post up video?


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