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Fixed vacuum leaks now need idle help

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Old Apr 19, 2021 | 04:56 PM
  #1  
88BLKTransAmGTA's Avatar
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From: Arkansas
Car: 1988 Trans Am GTA
Engine: 5.7 L98
Transmission: 700R4
Axle/Gears: 3.77
Fixed vacuum leaks now need idle help

Alright I am trying this again. I smoked as many places as I could, found one leak fixed it.
car is still dying when I could to a stop or slowly idle on the move..
Now I am trying to set my minimum idle but I can't get the car to run with the Iac valve unplugged
Steps I am doing
1.a&b bridged
2. Turn on ignition
3.Wait 30 seconds and unplug iac.
4. Try to start it and it will only start with accerator pressed and I cant get past that step because my car will only run with me pressing the gas. It will not idle with iac unplugged. What am I doing wrong?

Last edited by 88BLKTransAmGTA; Apr 19, 2021 at 06:41 PM.
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Old Apr 19, 2021 | 06:01 PM
  #2  
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From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Fixed vacuum leaks now need idle help

I'm not well versed in MAF tuning but if the throttle blades are nearly shut then open the blades a little until it runs with the iac unplugged. If they're open pretty far already, then close them.
Timing could be another issue. If ignition timing is too far off you may not be able to run it with the iac off as well. A "2 problems combined" problem.
Just tossing out ideas. Again, I'm not super familiar with MAF tuning.
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Old Apr 21, 2021 | 06:30 AM
  #3  
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Re: Fixed vacuum leaks now need idle help

Since it wasn't mentioned in the details, I'll mention it. The engine must be at full, normal operating temperature before the minimum air position adjustment is performed. There should also be no error codes, or in other words, the ECM should not be in backup fuel/spark mode.

If these conditions are correct, the throttle will need to be opened enough to allow the engine to idle. Adjusting the throttle stop screw will be necessary to maintain some idle speed, and after the engine has been running in that way for several minutes the target idle RPM can be set.

Of course, the throttle body bores and throttle plates all need to be fully cleaned before any adjustment is made. Remember to readjust the TPS closed-throttle voltage after the minimum air position is set.
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