Boss 302 Intake Manifold for 2011 Mustang GT 5.0 -

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Old 05-11-2012, 02:40 AM   #1
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Join Date: May 2012
Location: New Jersey
Posts: 1
Default Boss 302 Intake Manifold for 2011 Mustang GT 5.0

ATTENTION:: I am purposely writing this for people who are having issues after installing the Boss 302 intake manifold on their 2011 Mustang GT. My reason for writing this is because I had problems: ROUGH IDLE/LOW IDLE then it stalled - it was next to impossible to find suggestions or help on what was here we go...

I ordered the Boss Power Pack from (the site is amazing - has everything Mustang). The Boss Power Pack included the C&L CAI, Boss 302 Intake manifold, and Bama tuner (optional was the strut tower brace since the original one will not fit over the new manifold - I got that as well). Install of the CAI is very simple.

Install of the intake manifold takes quite a bit more time. I had a family member with a good collection of tools which was very helpful. The main thing that was most useful was a really good collection of socket wrenches. Installation is pretty easy following the directions you find on the internet, BUT THIS IS WHERE MY INSTRUCTIONS COME IN!!!

When you remove the fuel rail GAS WILL DRAIN so have your rags ready!!! To remove the rail you need to disconnect the fuel injectors and THIS IS THE MOST IMPORTANT PART!!!

There are 8 fuel injectors (4 on each side). On the top of each fuel injector ther is a blue "O" ring which slides into the fuel rail. On the bottom of each fuel injector there is a green "O" ring that fits into the intake manifold.

When pulling the fuel injectors from the original manifold I did not realize one of the green "O" rings and gotten stuck. I completed installation and started driving the car...

The car stalled when i first started which is actually expected. After restarting it had a terribly rough and low idle and then it stalled again. The car should really feel just like it did before install - very smooth. The intake manifold does not add any extra sound or feeling while idling.

I test drove the car after install and tuning and for sure that s#!+ moved fast as hell!!! But when i pulled into the driveway the idle was so low and rough and the CEL was on.

This continued for a few days...

I looked online and had alot of trouble finding suggestions, which is why I'm making this post! The best suggestion I found was to check the "O" rings on the fuel injectors.

I looked at the old intake manifold and sure enough there was one of the GREEN "O" RINGS stuck in the manifold. When I ran the diagnostics with my tuner it said "cylinder 3 misfire". it could potentially say something different for you depenting on which "O" ring is stuck - I'm not sure. I've also read through my hours of research that scratches in the "O" ring will cause the same problem so you need to be very careful with them. They actually will cause your engine to run different and your car will stall if they are not intact.

After all the research I did and seeing that one suggestion about the "O" rings and finding the one stuck in my old manifold I was able to put it on the corresponding fuel injector the car runs just like normal. The CEL turned off by itself after driving maybe 10+ miles. The car is still fast as F***...

So for those of you thinking of doing this mod it is most def worth it but just take my suggestions in mind!!!
theshocker115 is offline   Reply With Quote
Old 06-04-2012, 04:00 AM   #2
Join Date: Jun 2012
Location: Washington
Posts: 3

Thanks for the heads up just purchased the power pack its in the mail.
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Old 08-18-2014, 08:38 PM   #3
Join Date: Aug 2014
Location: Pa
Posts: 3

Thanks for the info! I just completed my Boss 302 intake & a BBK 90mm Throttle Body & was having the same issue. I looked at the stock intake & guess what was in there? An O-Ring! I'll put it in tomorrow & see if that's my problem. Thanks again for posting this issue because I would still be looking for the problem!!
11GT5Oh is offline   Reply With Quote

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