Loosing boost in 1st and 2nd - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 8 Old 04-29-2003, 11:38 PM Thread Starter
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Loosing boost in 1st and 2nd

A few days ago I took it out for a ride. When I mashed it to the floor the boost shot up starting at 2000rpm as usual and then at arounf 5000rpm it fell on it's face. Boost went to the floor. In second the same thing. Third it stayed at 9 psi which is where i run. Now when I'm infirst it won't make boost at all. it won't make boost until third gear then it stays at 9lbs without any problems. Any ideas?? EGT is 1400. I thought it was the clutch so i dropped the tranny and it looks fine if it was slipping i should see some marks right??


1986 stang with TF TW heads and a Street intake, 36 pound injectors and pro-m calibrated MAF, 89 computer, Borla exhaust, Stock TB and CAM, roller rockers 1.6 ratio, stock shortblock with studded mains, and a T-5, twin T-3 .60/.63 turbo's ITS heafers and downpipes, Huge 24X16X4 intercooler, Autometer gauges idles like a kitten with stock computer!!!!
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post #2 of 8 Old 04-30-2003, 12:04 AM
 
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hmm... sounds like a clutch problem...

How about running it SLOW? does boost come on then?

GOODLUCK

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post #3 of 8 Old 04-30-2003, 01:00 AM
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it would be kinda hard to "run it slow" and make boost, the bypass/blowoff valve would just remain open and keep venting the air and not allow it to see positive pressure at the intake (read boost) unless you went wide open throttle at which point you would be back to square one b/c you wouldn't be "running it slow"
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post #4 of 8 Old 04-30-2003, 06:48 PM
 
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Might be blowing out your spark. Try a narrower gap or something like a MSD system.
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post #5 of 8 Old 04-30-2003, 07:29 PM Thread Starter
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I considerd the spark as well. Howevrer why would it make boost in third?

1986 stang with TF TW heads and a Street intake, 36 pound injectors and pro-m calibrated MAF, 89 computer, Borla exhaust, Stock TB and CAM, roller rockers 1.6 ratio, stock shortblock with studded mains, and a T-5, twin T-3 .60/.63 turbo's ITS heafers and downpipes, Huge 24X16X4 intercooler, Autometer gauges idles like a kitten with stock computer!!!!
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post #6 of 8 Old 05-01-2003, 07:24 PM
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If your tires spin, you lose the load on the engine and boost will drop. It's not unheard of to hook up then break 'em loose near the top end with a turbo. 3rd gear = more load and harder to spin the tires, hence constant boost.

~Greg
Calibrated Success, Inc. EFI Training, Tuning, Consulting
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post #7 of 8 Old 05-01-2003, 11:00 PM
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Lightbulb

I agree with Turbolx. The boost would not be lost in one gear and not another. Load is load. The only way you would lose the boost is if you lose the load. Try starting out normal driving get to speed in second at about 2000 rpms and hit it. If you don't spin you shoud see your boost. If not their has to be something wrong with your wastegate. Other than that I don't know what else it could be.

Are you sure the cluth is not slipping? Get a buddy in the car. Have him or her look at your tires to see if they are spinning or not. If you lose boost like you have just blown the tires off but the tires are not spinning than the clutch is bad.

Good luck. Hope this was helpfull.

Rob
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post #8 of 8 Old 05-02-2003, 09:31 AM Thread Starter
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I was testing my actuators and found one to be leaking vacuum. It doesn't hold any! I know they usually cause too much boost could they ever cause too litle. I have internal T3 waste gates

1986 stang with TF TW heads and a Street intake, 36 pound injectors and pro-m calibrated MAF, 89 computer, Borla exhaust, Stock TB and CAM, roller rockers 1.6 ratio, stock shortblock with studded mains, and a T-5, twin T-3 .60/.63 turbo's ITS heafers and downpipes, Huge 24X16X4 intercooler, Autometer gauges idles like a kitten with stock computer!!!!
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