Cobra Jet II Vacuum Leak

[SlowyoteJay]

Alright guys, I’ve been trying to figure this out on my own for the past 3 days and can’t seem to figure it out. I installed the new cobra jet intake manifold, and apparently I have a vacuum leak somewhere but I can’t figure out where and p0443, p0300, and p0316 codes. I got the Steeda max flow closed box air intake.

I have the passenger side pcv hose connected, ran the brake booster straight to the drivers said of the intake manifold (so deleted the evap hose and sealed of the opening that sits under the brake booster), and blocked off one of the openings in the rear drivers side of the intake manifold (not sure what it would be used for). I’ve triple checked the silicone hoses that connect the intake elbow to the throttle body and air filter, and they are secured. I did have to make a hole in the intake elbow to put the valve the drivers side pcv and it doesn’t fit snug. Like when the pcv hose is connected, it pulls the valve a little.

Oh and it is tuned.

Could that be where the leak is coming from? I was going to buy/make a pcv breather for the drivers side and either replace that elbow with a new one to delete that valve or just get a PMAS intake but wanted suggestions first

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[glockholiday]

With it running spray starting fluid around any areas a vacuum leak could be possible, when rpms change because it sucked some in you've found your leak.

 

[Torinate]

Smoke test… maybe all the hoses are fine and leaking at injectors or runner o-rings?

 

[K4fxd]

Smoke test is the way to go.

Did you have to lower the engine or modify the hood?

 

[mech94]

Off topic but did you have to lower the engine for the hood to close

 

[SlowyoteJay]

Hood closes fine but does come in contact with hood towards the front of the manifold. I have lowering mounts installed but left it at stock height due to fitment issues with

 

[SlowyoteJay]

Did have to take out the liner though

 

[SlowyoteJay]

Smoke test… maybe all the hoses are fine and leaking at injectors or runner o-rings?

Can it still leak at the injectors even though they were pressed down and torqued to spec?

 

[K4fxd]

Can it still leak at the injectors even though they were pressed down and torqued to spec?

yes

 

[K4fxd]

If your PCV hose is loose I'd swap the hose for a rubber one and use clamps. If you still have a leak then I'd rent or buy a smoke machine.

 

[Torinate]

Can it still leak at the injectors even though they were pressed down and torqued to spec?

Yes. I’ve also seen people put a little tear in the injector o-rings when installing and not using enough lube and forcing them in. I’ve also seen people where the intake o-ring (rectangle lol) comes out a little and kind of gets folded under and doesn’t seal.
How do you know you have a vacuum leak? Gauge? Running rough? Wacky fuel trims? What vacuum does it pull at idle?

 

[Torinate]

Sorry. My bad. Just saw your codes.
So a purge code and misfire codes…

Did you put the purge valve back on correctly and plug the connector back in? Check for a bent pin.Pull it off and check the o-ring on it. As K4XD said, check the hoses and use clamps as necessary.

 

[SlowyoteJay]

Yes. I’ve also seen people put a little tear in the injector o-rings when installing and not using enough lube and forcing them in. I’ve also seen people where the intake o-ring (rectangle lol) comes out a little and kind of gets folded under and doesn’t seal.
How do you know you have a vacuum leak? Gauge? Running rough? Wacky fuel trims? What vacuum does it pull at idle?

I was told it was a vacuum leak by palm beach after sending idle and drive logs. It’s a rough idle and the rpms drop really low to around 500 and has died a couple times

 

[SlowyoteJay]

Sorry. My bad. Just saw your codes.
So a purge code and misfire codes…

Did you put the purge valve back on correctly and plug the connector back in? Check for a bent pin.Pull it off and check the o-ring on it. As K4XD said, check the hoses and use clamps as necessary.

I’m not running a purge valve so that plug for it is just hanging to the side because I was told it’s not needed for this cobra jet. I saw it used on the old one but I don’t see a spot for it on the new one. I’ll probably take out the fuel rail and reinstall the injectors to see if any of them are loose/ not fit properly. Can I use throttle body cleaner to check for vacuum leaks or should I just get starter fluid?

 

[K4fxd]

and blocked off one of the openings in the rear drivers side of the intake manifold (not sure what it would be used for).

Purge valve

I did have to make a hole in the intake elbow to put the valve the drivers side pcv and it doesn’t fit snug.

I would make sure this is sealed before I messed with anything else.

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