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Fast 90 Intake Manifold Issues

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Old Apr 18, 2011 | 11:19 PM
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Default Fast 90 Intake Manifold Issues

Just installed new h/c/i in my 99 ss. Im running stock 243's and a tqr v2. cam. The car starts up and idles fine with the stock intake manifold on, but when I switch to the FAST 90 it shoots up to about 3k real fast and then the rpms gradually decrease until it dies (in about 15-20sec). The issue i had with the FAST was that there was no vacuum inlet for the MAP so i used a T connecter to intercept the air line in the back of the intake manifold (on the opposite side the brake booster connects to). I also tried disconnecting the MAP sensor altogether and it doesnt shoot up to 3k any more, but it idles at under 500rpm until it dies.
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Old Apr 18, 2011 | 11:27 PM
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you do know you have to get it tuned with the fast intake on it
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Old Apr 18, 2011 | 11:38 PM
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The FAST will bolt right on and drive just fine without being tuned. It may be a little lean at RPM but will drive fine at part throttle.

There is a port on the rear of the intake for the MAP. It just has no clip to retain the sensor.

You have a large vaccum leak. There could be a crack in the intake from a nitrous backfire (if you bought the intake used), or from the valley cover bolts cracking the plastic on the bottom of the intake (if the correct button head fasteners werent used), or from the hole you didnt see for the MAP.
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Old Apr 18, 2011 | 11:59 PM
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yeah i know it has to get tuned...but i'm just sayin..it doesn't idle right, i was told that it should idle fine with the FAST intake bolted on. But as of right now we just tried shooting brake cleaner around the intake and found out that the intake itself where the top half meets the bottom half is leaking, when i bought the FAST intake i never changed out the gasket between the top and bottom half of it...so now i'm going to order a new one. So far this is my guess as to what's going wrong here, any other suggestions?
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Old Apr 19, 2011 | 12:00 AM
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Yea you have a vacuum leak some where, like whistler said it if used it could be cracked
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Old Apr 19, 2011 | 12:04 AM
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Originally Posted by Whistler
The FAST will bolt right on and drive just fine without being tuned. It may be a little lean at RPM but will drive fine at part throttle.

There is a port on the rear of the intake for the MAP. It just has no clip to retain the sensor.

You have a large vaccum leak. There could be a crack in the intake from a nitrous backfire (if you bought the intake used), or from the valley cover bolts cracking the plastic on the bottom of the intake (if the correct button head fasteners werent used), or from the hole you didnt see for the MAP.
yeah, i got the intake used...the person who had it before me modified the back of the intake manifold, he slightly cut it and remolded it to fit the firewall for the back of his c6..and there was only 1 hole in the back of the intake mani as opposed to having a hole for the MAP like you explained...
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Old Apr 19, 2011 | 12:07 AM
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I hope you get it fixed soon suck to here about your problem!
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Old Apr 19, 2011 | 12:42 AM
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here are the photos, we just decided to take the intake manifold off for tonight
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Old Apr 19, 2011 | 12:58 AM
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the person who had it before me modified the back of the intake manifold, he slightly cut it and remolded it to fit the firewall for the back of his c6
I find it very hard to believe all that was done to it just to make it fit on a Vette..That thing got hacked. And what is that bolt and washer doing on the back left side?? I hope you got that intake for cheap...It deffinantly looks like it was damaged/cracked a good a mount and someone attempted to fix it.
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Old Apr 19, 2011 | 02:20 AM
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It was sold for a reason! The pics never lie!
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Old Apr 19, 2011 | 02:22 AM
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Originally Posted by Jimmy P
I find it very hard to believe all that was done to it just to make it fit on a Vette..That thing got hacked. And what is that bolt and washer doing on the back left side?? I hope you got that intake for cheap...It deffinantly looks like it was damaged/cracked a good a mount and someone attempted to fix it.
exactly what I was thinking. Good luck
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Old Apr 19, 2011 | 08:34 AM
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Did you change out your valley cover bolts?
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Old Apr 19, 2011 | 08:54 AM
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Looks almost like it was damaged in a backfire or something. That hole back part looks more like it was broke and then fixed than it does cut and filled.
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Old Apr 20, 2011 | 01:54 AM
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He figured it out, it was exactly what he said...It was the gasket where the top half of the intake meets the bottom half of the intake... that the thing runs great now. What kind of numbers do u guys think it'll push? stock bottom end 99 ls1, 243 zo6 heads, Torquer V2 cam, FAST 92 intake mani w/ FAST 92 TB, SLP Loudmouth (not sure if it's 1 or 2), Texas Speed 1 7/8 Longtubes, Custom 3" Y, SLP Lid..i think that's it, hope i'm not missing anything.
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Old Apr 20, 2011 | 02:51 AM
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Glad he got it figured out. That intake is still hacked to **** but I guess if it runs ok now then run with it.
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Old Apr 23, 2011 | 11:02 PM
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glad you figured it out
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