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305 surging after warm at idle

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Old Sep 3, 2012 | 08:01 PM
  #1  
Nighthawkf-117's Avatar
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From: Minnesota
Car: 91' Camaro RS
Engine: 305 TBI V8
Transmission: 700/R4
Axle/Gears: Stock
305 surging after warm at idle

Hi guys,
Im new to the forum. I have a 91' camaro RS with the 305 TBI. It starts and runs good but after the car gets warmed up somtimes at a red light when my foot is off the gas the engine will surge. Its like it want to die then the computer recovers and the process repeats. It doesnt happen often and at one idle it will and one it wont on the same drive.
Ive noticed if at a red light I roll up very slowly before stopping it wont surge but if I do a harder stop it will. Like if im giving it time to adjust to the idle it will be fine but if I dont it will surge.
Ive also noticed poor fuel economy and a semi high idle.
Any Ideas? Its my first car so I dont want to throw too much into it. I just want it to run nice. Im going to pop the EGR valve off tommarow to see if it is shot and mabey replace the o2 sensor just incase.
Thanks
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Old May 1, 2017 | 07:42 PM
  #2  
wisemanz28's Avatar
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Re: 305 surging after warm at idle

Did you ever find the problem , my car is doing the same thing.
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Old May 1, 2017 | 08:05 PM
  #3  
Schurkey's Avatar
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Re: 305 surging after warm at idle

Wild Guess: Dirty IAC passages, dirty throttle body. Perhaps the IAC motor is getting weak?

Connect a scan tool, look at the commanded idle speed vs. the actual idle speed. For that matter, look at all the rest of the data stream.
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Old May 3, 2017 | 07:25 AM
  #4  
KITT1983's Avatar
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From: Boston, MA
Car: 1983 Pontiac Trans Am Daytona 500
Engine: Crossfire 305ci V8
Transmission: Jasper 700R4 4 speed Automatic
Axle/Gears: 3.23 limited slip/posi
Re: 305 surging after warm at idle

any vacuum leaks ?
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Old May 3, 2017 | 08:13 PM
  #5  
wisemanz28's Avatar
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Re: 305 surging after warm at idle

no vacuum leaks, going to look at the iac this weekend
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Old May 14, 2017 | 05:09 AM
  #6  
thomas1976's Avatar
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Joined: Jun 2006
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From: West-Central
Car: 91 Trans am
Engine: built 360 TBI
Transmission: built 700r4
Axle/Gears: 10bolt/3.23
Re: 305 surging after warm at idle

Tired fuel pump (check fuel pressure).
Failing alternator voltage regulator (check if voltage drops at lower rpm).
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