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Discussion Starter · #1 ·
Hello. I need help with my 03 Accord Ex (3.0 V6). I am getting a P-2279 code Air intake system leak. I hear a “hissing” sound when engine is on. I’m having trouble spotting the issue in the air flow. I have checked all vacuum lines and they all seem to be fine. I even replaced some of them to make sure. The hissing air leak sound is coming from near or in between the egr valve (which I also recently replaced) and the fuel lines connects to the fuel rails. Any help is appreciated.

Ps. Does anybody know this part? (See picture uploaded).Hissing is coming from its general area in the engine.
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Car is also surging while idle.
 

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07 Accord Sedan EX V6 Auto
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The part you are pointing at is the coolant temperature sensor. It is not related to the engine vacuum system. The throttle body is right above it, I'd make sure your throttle body gasket is still intact and in good condition, and the throttle body is torqued down correctly.

If you want, you can get carb cleaner and spray it around suspected leaks in the engine. The engine will surge if it starts to suck in the carb cleaner. Be careful though, carb cleaner is very flammable. If that doesn't work, take it to a mechanic with a smoke machine to find the leak.
 

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Elvira
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^^^^^^Do this

Also check around the PCV valve for damaged oring . The PCV may also be stuck open causing the surge.

Also might want to check the IACV (Intake Air Control Valve) for proper operation and/or leaks. That could be hissing as well as causing the surge at idle.
 

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Check the flex tube between throttle body and air cleaner top cover, even though mine is not hissing yet, I found that nipple on the side of if has cracks. I also believe that on mine short hose from pcv maybe be hissing as it is hard as a coffin nail. Definitely use suggestions above to check for leaks using something like brake cleaner sprayed and listen for engine sound change and rpm fluctuations. Since you recently had egr valve serviced, check in that area as well. Did your hissing started right after egr valve replacement or some time after it ?
 

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Discussion Starter · #5 ·
The part you are pointing at is the coolant temperature sensor. It is not related to the engine vacuum system. The throttle body is right above it, I'd make sure your throttle body gasket is still intact and in good condition, and the throttle body is torqued down correctly.

If you want, you can get carb cleaner and spray it around suspected leaks in the engine. The engine will surge if it starts to suck in the carb cleaner. Be careful though, carb cleaner is very flammable. If that doesn't work, take it to a mechanic with a smoke machine to find the leak.
Thank you for the response. I did spray some carb cleaner around throttle body and it caused a little bit of engine power shift. I replaced the throttle body gasket but it’s still doing the same issue and it’s still hissing. I changed all four tires today and I should have asked for next time. Maybe I go get one at Walmart tonight to try the smoke machine method.

^^^^^^Do this

Also check around the PCV valve for damaged oring . The PCV may also be stuck open causing the surge.

Also might want to check the IACV (Intake Air Control Valve) for proper operation and/or leaks. That could be hissing as well as causing the surge at idle.
I recently also replaced the Pcv valve along the way of trying to resolve this surging and hissing issue. Do you have a link to the intake air control valve you mentioned? I tried to look it up in rock auto but with no luck. I have also heard of the idle control valve. Is it the same thing and just some people call it different names? Sorry but I’m an amateur dyi mechanic. Have a lot of questions.

Check the flex tube between throttle body and air cleaner top cover, even though mine is not hissing yet, I found that nipple on the side of if has cracks. I also believe that on mine short hose from pcv maybe be hissing as it is hard as a coffin nail. Definitely use suggestions above to check for leaks using something like brake cleaner sprayed and listen for engine sound change and rpm fluctuations. Since you recently had egr valve serviced, check in that area as well. Did your hissing started right after egr valve replacement or some time after it ?
It had the hissing before. I’m putting more of a close ear and I think it’s coming underneath the plenum. Any gaskets down there that may cause the hissing? Do I need to dig a lil deeper you think to find the trouble?

I’m thinking lower intake gasket. Does the “hissing” even something that would come from the lower intake gasket being bad. Or even the plenum gasket (bottom)?
 

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07 Accord Sedan EX V6 Auto
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^^^^^^Do this

Also check around the PCV valve for damaged oring . The PCV may also be stuck open causing the surge.

Also might want to check the IACV (Intake Air Control Valve) for proper operation and/or leaks. That could be hissing as well as causing the surge at idle.
The V6 has an electronically controlled throttle body, it has no intake air control valve. It also has no MAF sensor, so the intake hose being damaged or completely absent also won't cause poor idle or a check engine light.
 

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Elvira
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The V6 has an electronically controlled throttle body, it has no intake air control valve. It also has no MAF sensor, so the intake hose being damaged or completely absent also won't cause poor idle or a check engine light.
My mistake the I4 had one

@JoseR the v6 has no IACV
 

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Discussion Starter · #10 ·
I did get around to use a smoke machine today. There is smoke coming out underneath the plenum as well as thru the top of the plenum. I’m thinking the lower intake manifold gaskets or the gasket underneath the plenum is damaged. I already ordered all the gaskets (including the top plenum gasket) to make sure I’m covering all bases. I will be changing them. Don’t know if you recommend that I start with just the top and bottom plenum gaskets and see how it plays out? Don’t really want to replace the lower intake manifold gaskets if I don’t have to.

Nope, 7th gen V6 always had electronic throttle body and MAP based metering. The I4 got a mid-run switch from cable-actuated to electronic.
Any idea what my problem would be?
 

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Discussion Starter · #12 ·
The gaskets looked to be in good shape. I followed a YouTube video for torque specs and sequence for tightening bolts. I haven’t gotten to the lower intake manifold. I’ve only got to the under the plenum gasket when I took the plenum off. I did order brand new gaskets for both (lower intake and under plenum gasket). I will be getting them soon in the mail and will install and update….do you know where I can find the sequence of the bolts and specs for the torque? Thanks

Parts start coming in tomorrow so I will update
 

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Discussion Starter · #13 ·
parts came and i replaced all gaskets but the lower intake gaskets. The car is still doing the hissing sound and it is still idle surging. You guys think it might be the lower intake gaskets after all?
 
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