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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 12:09 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 12:16 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 12:23 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 12:26 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 12:31 PM

gotta be an exhaust leak.

anthonyj9h 05-31-2011 12:32 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 12:52 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 12:53 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 01:02 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 01:05 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 01:08 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 01:39 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 01:42 PM

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

hypurone 05-31-2011 01:59 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...


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