Intake Manifold Vacuum Leak - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

augrad94 · 08-14-2012, 10:35 AM

Has anyone else had this problem, a vacuum leak, at the intake manifold? I have been having major issues with my car the past few weeks, clicking noise, rough idle, and seems to be misfiring on the "back" 4 cylinders etc. I believe it has been tracked down to this by the shop that did the cam, headers, etc. These guys have gone out of their way to diagnose this problem!

It appears some of the 08-09 ls3 have a deformity at the rear of the intake manifold at the #8 intake port (passenger side rear port) that allows the gasket to get sucked in enough to cause a large vacuum leak.

Has anyone else had a similar issue? I did a search and couldn't find anything.

Nitrostangracingautosport · 08-14-2012, 10:48 AM

Should be easy enough to verify if the Intake is off. Just need a large Straight Edge to check.

SC2150 · 08-14-2012, 03:04 PM

Only issues we see are when someone tightens it down and pinches the hrness for the can sensor and the oil prssue switch between the IM and the head. Happens all the time and that can deform the IM....but thats not a GM issue, thats a careless installer issue.

NC-V · 08-14-2012, 10:26 PM

Here's all the data:
Recent mods: 3-bolt Cam/springs/p-rods/chain/damper, Headers/HF cats/catback, Catch Can (elite), New Strong MAF
Already had CAI.

After install and tune: idle was solid ~925rpm A/C on or off, MAP steady around 52kpa, and MAF around 1.6lb/min. All Fuel trims +/- 4. Car Ran great.

~34,000 miles on car. Less than 1000 miles after mods: Entering Highway from yeild, car hiccups, stumbles then picks up and then takes off. Now idles rough with random misfires, and throws P0171 and P0174 (lean bank 1, lean bank 2).

Log car now: idle is very rough, misfiring, Reset LTFT's and then climb right back to +25 very quickly, MAP is very erratic from ~50 - ~75 Kpa, MAF readings are about the same as before.

Car is about an hr away from me and just looked at it last night. First thoughts are Vac leak. Removed CC from equation-no change. Plugged Evap port-No change. Removed booster hose from booster and plugged-no change. Removed throttle body and checked O-ring, no signs of damage or leaks-no change. Sprayed hoses, ports and around TB with start fluid and watched for changes-no change. Couldn't remove manifold at this time (had limited tools and hr from shop), so I'll be back with the car Saturday with a spare manifold and gaskets. Also removed coil plugs one by one, this showed rear cylinders weaker than fronts (misfiring more often), corroborated by header temps, cooler towards rear.

Other things Checked out already:
Header bolts and gaskets are tight/good/no leaks. Removed valve covers and all springs/keepers/rocker arms and p-rods are correct and still torqued/not broken. Hose clamps on CAI are tight. Checked plugs and wires. Fuel pressure is steady 58-59psi

This seams classic Vac leak and only place I couldn't check at the time was the bottoms and sides of the manifold ports and the back side of the manifold by the booster elbow. There is some oil residue on the booster hose and around the booster elbow, not sure if that is from a leak in the manifold itself or seepage from the oil pressure sensor. Thing is the manifold was never removed.

Work with LS's every day and Camaro's specifically,but never had a vac leak this big I haven't been able to find pretty easily (don't have a smoke machine at my disposal). I'll be back in front of the car Saturday morning, I am open to any and all suggestions or things I could have possibly overlooked. Otherwise I plan pop the intake real quick and check the port O-rings/ look for cracks around the booster elbow in the back.

Thanks for any and all thoughts. Just want to get Hu (OP) burning those tires off again.
-Kyle

augrad94 · 08-15-2012, 06:24 AM

@SC2150: The manifold has never been off the car so it shouldn't be over tightened. Unless from the factory.

@NC-V(Kyle) Thanks for all the details, and for all your work getting to the root of the problem! I would say a 1 hour drive each way and 3 hours of troubleshooting deserves a

SC2150 · 08-15-2012, 11:15 AM

I thought I saw a cam was installed.....hard to do that w/out pulling the intake but not impossible...

NC-V · 08-15-2012, 11:25 AM

Quote:

Originally Posted by SC2150

I thought I saw a cam was installed.....hard to do that w/out pulling the intake but not impossible...

Cam was installed, Throttle body was removed along with front drive accessories, but no need to pull intake. Its an ls3 so no conversion/head pull/lifter swap. Sorry if I left that out to begin with.

MikeOD · 08-16-2012, 03:39 PM

Quote:

Originally Posted by SC2150

I thought I saw a cam was installed.....hard to do that w/out pulling the intake but not impossible...

It's actually really exactly the same to swap a cam with or without pulling the intake unless you need to change the lifters...probably harder if you do pull the intake because it's that much more work to R&R it.

1Camaro2SS · 08-16-2012, 10:33 PM

Quote:

Originally Posted by MikeOD

It's actually really exactly the same to swap a cam with or without pulling the intake unless you need to change the lifters...probably harder if you do pull the intake because it's that much more work to R&R it.

What do you mean to R and R the intake?

Nessal · 08-16-2012, 10:40 PM

YES! I HAD THIS SAME EXACT ISSUE.

It turns out that the seal on the #8 runner on the intake manifold melted so it allowed outside air to get sucked in unmetered. That cause the car to run lean and started to throw codes. After removing the intake manifold, you could see the seal and runner melted. A smoke test on the intake manifold helped determine that the leak was introduced in that area.

NC-V · 08-17-2012, 05:43 AM

Quote:

Originally Posted by 1Camaro2SS

What do you mean to R and R the intake?

Remove and Replace

Thanks Nessal, I remembered reading your thread a little while back. I'm pulling the intake tomorrow morning so we will see what I find.

08-14-2012, 10:35 AM	#1
augrad94 Drives: 2010 1SS/RS Black/Black Join Date: May 2008 Location: Fort Mill SC Posts: 144	Intake Manifold Vacuum Leak Has anyone else had this problem, a vacuum leak, at the intake manifold? I have been having major issues with my car the past few weeks, clicking noise, rough idle, and seems to be misfiring on the "back" 4 cylinders etc. I believe it has been tracked down to this by the shop that did the cam, headers, etc. These guys have gone out of their way to diagnose this problem! It appears some of the 08-09 ls3 have a deformity at the rear of the intake manifold at the #8 intake port (passenger side rear port) that allows the gasket to get sucked in enough to cause a large vacuum leak. Has anyone else had a similar issue? I did a search and couldn't find anything. __________________ Black/Black 1SS 6sp manual , RS package, Boston sound system 1100 10/14/2008 2000 03/26/2009 3000 03/26/2009 3300 5/09/2009 3400 5/13/2009 3800 5/22/209 VIN 111607 4000 5/22/209 4104 5/22/209 4B00 5/22/209 4200 Not sure of date but it has shipped! 6000 6/12/2009 CAM, Headers, exhaust build thread here.

08-15-2012, 06:24 AM	#5
augrad94 Drives: 2010 1SS/RS Black/Black Join Date: May 2008 Location: Fort Mill SC Posts: 144	@SC2150: The manifold has never been off the car so it shouldn't be over tightened. Unless from the factory. @NC-V(Kyle) Thanks for all the details, and for all your work getting to the root of the problem! I would say a 1 hour drive each way and 3 hours of troubleshooting deserves a __________________ Black/Black 1SS 6sp manual , RS package, Boston sound system 1100 10/14/2008 2000 03/26/2009 3000 03/26/2009 3300 5/09/2009 3400 5/13/2009 3800 5/22/209 VIN 111607 4000 5/22/209 4104 5/22/209 4B00 5/22/209 4200 Not sure of date but it has shipped! 6000 6/12/2009 CAM, Headers, exhaust build thread here.

08-14-2012, 10:48 AM	#2
Nitrostangracingautosport Drives: Brand X Join Date: Oct 2011 Location: Margate Florida Posts: 28	Should be easy enough to verify if the Intake is off. Just need a large Straight Edge to check.

08-14-2012, 03:04 PM	#3
SC2150 Account Suspended Drives: 2012 Camaro RS, RX supercharged Join Date: Dec 2009 Location: Bradenton, FL Posts: 6,063	Only issues we see are when someone tightens it down and pinches the hrness for the can sensor and the oil prssue switch between the IM and the head. Happens all the time and that can deform the IM....but thats not a GM issue, thats a careless installer issue.

08-14-2012, 10:26 PM	#4
NC-V Drives: cts-v Join Date: Dec 2011 Location: Mooresville, NC Posts: 506	Here's all the data: Recent mods: 3-bolt Cam/springs/p-rods/chain/damper, Headers/HF cats/catback, Catch Can (elite), New Strong MAF Already had CAI. After install and tune: idle was solid ~925rpm A/C on or off, MAP steady around 52kpa, and MAF around 1.6lb/min. All Fuel trims +/- 4. Car Ran great. ~34,000 miles on car. Less than 1000 miles after mods: Entering Highway from yeild, car hiccups, stumbles then picks up and then takes off. Now idles rough with random misfires, and throws P0171 and P0174 (lean bank 1, lean bank 2). Log car now: idle is very rough, misfiring, Reset LTFT's and then climb right back to +25 very quickly, MAP is very erratic from ~50 - ~75 Kpa, MAF readings are about the same as before. Car is about an hr away from me and just looked at it last night. First thoughts are Vac leak. Removed CC from equation-no change. Plugged Evap port-No change. Removed booster hose from booster and plugged-no change. Removed throttle body and checked O-ring, no signs of damage or leaks-no change. Sprayed hoses, ports and around TB with start fluid and watched for changes-no change. Couldn't remove manifold at this time (had limited tools and hr from shop), so I'll be back with the car Saturday with a spare manifold and gaskets. Also removed coil plugs one by one, this showed rear cylinders weaker than fronts (misfiring more often), corroborated by header temps, cooler towards rear. Other things Checked out already: Header bolts and gaskets are tight/good/no leaks. Removed valve covers and all springs/keepers/rocker arms and p-rods are correct and still torqued/not broken. Hose clamps on CAI are tight. Checked plugs and wires. Fuel pressure is steady 58-59psi This seams classic Vac leak and only place I couldn't check at the time was the bottoms and sides of the manifold ports and the back side of the manifold by the booster elbow. There is some oil residue on the booster hose and around the booster elbow, not sure if that is from a leak in the manifold itself or seepage from the oil pressure sensor. Thing is the manifold was never removed. Work with LS's every day and Camaro's specifically,but never had a vac leak this big I haven't been able to find pretty easily (don't have a smoke machine at my disposal). I'll be back in front of the car Saturday morning, I am open to any and all suggestions or things I could have possibly overlooked. Otherwise I plan pop the intake real quick and check the port O-rings/ look for cracks around the booster elbow in the back. Thanks for any and all thoughts. Just want to get Hu (OP) burning those tires off again. -Kyle

08-15-2012, 11:15 AM	#6
SC2150 Account Suspended Drives: 2012 Camaro RS, RX supercharged Join Date: Dec 2009 Location: Bradenton, FL Posts: 6,063	I thought I saw a cam was installed.....hard to do that w/out pulling the intake but not impossible...

08-16-2012, 10:40 PM	#10
Nessal Drives: Exige, Miata, Ghia Join Date: Jun 2011 Location: CA, Bay Area Posts: 2,309	YES! I HAD THIS SAME EXACT ISSUE. It turns out that the seal on the #8 runner on the intake manifold melted so it allowed outside air to get sucked in unmetered. That cause the car to run lean and started to throw codes. After removing the intake manifold, you could see the seal and runner melted. A smoke test on the intake manifold helped determine that the leak was introduced in that area.