Gt350 intake manifold swap

[Dsavage13]

So just a few days ago I swapped yo the gt350 intake manifold on my 2016 Mustang Gt and getting three codes p0171, p0174, and p0507. Car idling around 1500-2000 rpm. Tuner is saying there's an vacuum leak, but I pulled manifold 3 times with no leaks also using gt350 TB and gt350 CAI. TIA!

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[WildHorse]

So just a few days ago I swapped yo the gt350 intake manifold on my 2016 Mustang Gt and getting three codes p0171, p0174, and p0507. Car idling around 1500-2000 rpm. Tuner is saying there's an vacuum leak, but I pulled manifold 3 times with no leaks also using gt350 TB and gt350 CAI. TIA!

Smoke test it.

 

[Dsavage13]

Smoke test it.

Will do i’ll let you know how that goes thanks

 

[GregO]

Car idling around 1500-2000 rpm.

New or used manifold and TB ?
Post up some pix of your vacuum line routings.

 

[Dsavage13]

New or used manifold and TB ?
Post up some pix of your vacuum line routings.

New manifold throttle body came off car around 50k and been stored in a safe place bought manifold from ford a week ago

 

[GregO]

@Dsavage13
The brake vacuum booster line is missing a spring clamp.

 

[Dsavage13]

@Dsavage13
The brake vacuum booster line is missing a spring clamp.

I thought that was the issue as well but I put a screw clamp on it

 

[Dsavage13]

What's going on with the IMRC vac line that runs down to the front of the engine? The older GT350 manifold had the IMRC vacuum routed internally at the back of the manifold. This one seems to have it external over the top of the manifold to the front. When did ford change that?

I can recommend getting an analogue vacuum gauge and run it with that at idle to see what the real vacuum is.

I have no idea when this was changed but vacuum inside car at idle is reading 14.5-16.0

 

[v8hgt]

ignore me.. its been so long since I installed mine I had forgotten what it looks like. Ive just checked my vacuum line routing at it looks the same as yours. Mine too has lower than stock vacuum readings on the dash, but I know these readings to be highly inaccurate. They are calculated not measured readings. I ended up buying one of these to measure the vacuum properly as I tried the smoke method and found no leaks.
https://www.amazon.co.uk/FreeTec-Va...5?keywords=vacuum+gauge&qid=1646237832&sr=8-5

When my dash reading shows approx 16-17 in/hg at idle, the vacuum meter shows a very healthy 21 in/hg. At that sort of vacuum you are going to HEAR any leaks!

 

[Dsavage13]

ignore me.. its been so long since I installed mine I had forgotten what it looks like. Ive just checked my vacuum line routing at it looks the same as yours. Mine too has lower than stock vacuum readings on the dash, but I know these readings to be highly inaccurate. They are calculated not measured readings. I ended up buying one of these to measure the vacuum properly as I tried the smoke method and found no leaks.
https://www.amazon.co.uk/FreeTec-Va...5?keywords=vacuum+gauge&qid=1646237832&sr=8-5

When my dash reading shows approx 16-17 in/hg at idle, the vacuum meter shows a very healthy 21 in/hg. At that sort of vacuum you are going to HEAR any leaks!

Thanks for this a ton

 

[v8hgt]

One more thing to mention.. Check your purge valve at the front of the manifold above the throttle body
https://www.americanmuscle.com/oe-solutions-mustang-evaporative-canister-purge-valve-911-222.html
These are known to be less than reliable. They open slightly sometimes to allow the engine to suck vapours from the fuel tank. When they fail you may experience problems restarting a hot car after filling the tank at the fuel station for instance.. If they fail in an always open state you may get a lower than normal vacuum at idle. You can tell if its failed by removing the vac line from the purge valve and putting your finger over it to feel for a vacuum. With the engine off, the valve should be closed. Put your finger over the valve and get someone else to start the car for you. you shouldn't feel any sucking until the revs rise. Don't forget to plumb the hose back on the valve after testing this out!

Also. What air filter are you running? I had a steeda gt500 filer on mine and concluded that the filter was so free flowing that I got 'fan wash'... ie when the fans kicked in, air was being blown onto the filter causing it to go lean, so the trims had to compensate. To a remote tuner this can resemble a vacuum leak in their logs.. ie the fuel trims have to add fuel to compensate for a lean running condition just as they would with a vacuum leak. I changed the filter to a stock gt350 one, and this problem stopped.

 

[Mdtaylorjr]

I ran my brake booster hose to the larger port on the manifold itself and left the smaller one capped. Off other than that everything looks good. Check fuel trims on either a scanner or your programmer if capable. Did you get the gt350 maf that comes with kit or did you use your GT one I believe they are different but not sure. Other than that look for cracks in the tube or holes in the lines.

 

[Dsavage13]

I ran my brake booster hose to the larger port on the manifold itself and left the smaller one capped. Off other than that everything looks good. Check fuel trims on either a scanner or your programmer if capable. Did you get the gt350 maf that comes with kit or did you use your GT one I believe they are different but not sure. Other than that look for cracks in the tube or holes in the lines.

Using gt maf believe so

 

[Dsavage13]

One more thing to mention.. Check your purge valve at the front of the manifold above the throttle body
https://www.americanmuscle.com/oe-solutions-mustang-evaporative-canister-purge-valve-911-222.html
These are known to be less than reliable. They open slightly sometimes to allow the engine to suck vapours from the fuel tank. When they fail you may experience problems restarting a hot car after filling the tank at the fuel station for instance.. If they fail in an always open state you may get a lower than normal vacuum at idle. You can tell if its failed by removing the vac line from the purge valve and putting your finger over it to feel for a vacuum. With the engine off, the valve should be closed. Put your finger over the valve and get someone else to start the car for you. you shouldn't feel any sucking until the revs rise. Don't forget to plumb the hose back on the valve after testing this out!

Will check this now

 

[Strokerswild]

I ran my brake booster hose to the larger port on the manifold itself and left the smaller one capped. Off other than that everything looks good. Check fuel trims on either a scanner or your programmer if capable. Did you get the gt350 maf that comes with kit or did you use your GT one I believe they are different but not sure. Other than that look for cracks in the tube or holes in the lines.

I did the same, brake booster to the large port that the OP has capped. The one on the aspirator was capped, so I left it that way.

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