434ci 2620/266 cam..vacuum 88-90kpa at idle?

[Snyper]

With a cam this size what should the vacuum be at idle? It seems as though the car is barely pulling any. The map shows 88-90 at idle and when I revv it up it drops down to 35 or so then goes right back up. Im also getting a map failure code (probably due to the very low vacuum at idle) I normally see in the 50s with my old setup. Also the fuel pressure regulator is working like it has no vacuum at all either so I know the map is reading correctly. I have a fast 102mm intake manifold and I had the wrong valley cover bolts on it and one day while tighening it down I heard a pop on the left side..I took it off..put the proper bolts on and very carefully inspected the intake manifold and could not find a single crack or split. I also notice around 2-3k I hear a whistle coming from the engine...any ideas? Im guessing its a pretty bad vacuum leak but I cant seem to find the damn thing.

[carlrx7]

its cracked somewhere, vacuum finds any leak

[Snyper]

I took the entire intake apart and saw nothing. I Resealed it and put it back together now waiting for the sealant in the rear to dry. The only thing I noticed was that the throttlebody to intake bolts were hand tight. I was able to take them all out with the socket turning it by hand. Hopefully that was it.

[HNK]

I have a 254-262 @.050 on a 113 in my 440 CI with 12.5 comp. idle is around 74. the cam you have is bigger and less stroke, dont know about your comp, but mid 80s would be probably normal.

[Snyper]

11.6:1

[edcmat-l1]

Edit: Just reread your post. Sounds like a vacuum leak. Find someone with a smoke machine and smoke it.

[Snyper]

Well I resealed the intake after finding no cracks..and made sure everything was tight. Now I start the car and it goes very lean and just stalls immediately. even if I give it gas it just starts strong then immediately dies. Ive changed nothing in the tune.

[edcmat-l1]

Well I resealed the intake after finding no cracks..and made sure everything was tight. Now I start the car and it goes very lean and just stalls immediately. even if I give it gas it just starts strong then immediately dies. Ive changed nothing in the tune.

Sounds like you fixed a vacuum leak.

[HNK]

Well I resealed the intake after finding no cracks..and made sure everything was tight. Now I start the car and it goes very lean and just stalls immediately. even if I give it gas it just starts strong then immediately dies. Ive changed nothing in the tune.

Hopefully you can get it sorted out with a tune. Would be curious to see where your Kpa will be with that cam and package.

[Snyper]

Why would it go super lean and die now? Almost like no fuel.

[Nodnarb]

Different area of the VE table

[DSteck]

Try re-enabling the MAF, just to trouble shoot.

[Snyper]

Still having the same issue. My intake is leaking from somewhere.. Right around 2krpm I hear a high pitched whistle (which is when the engine should be pulling the most vacuum) I also notice right around that area, when running VE only, my table jumps up significantly just to balance out the AFR. My car should be idling in the mid 70s somewhere and the VE shouldnt need to jump up over a 1000 within a few hundred rpm. I'm hoping that this will also be able to explain the "drag" I experience from 2-3krpm. It runs beautiful from 1-2...then drags, then around 3k cleans right up. I've checked my intake for leaks at least 3 times and im not really sure where to go from here. My only thought is that the intake isn't fitting on the engine properly maybe due to my block being milled when the engine was rebuilt twice.