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5.7 TBI - high idle

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EdontheBeach
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5.7 TBI - high idle

Postby EdontheBeach on Wed Mar 13, 2013 10:33 am

fellas - i have an 83 cutlass cruiser with a 92 350 TBI from a roadmaster. if i drive at anything over about 30-35mph, when i come to a stop the engine continues at a high idle (1200-1300) for 30 or 40 seconds after i stop before settling down to 750rpm. i've checked the gas cable and don't feel it hanging up. any idea what might be the culprit? this is my first TBI car, i don't know where or what to look for.

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olds307 and 403
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Re: 5.7 TBI - high idle

Postby olds307 and 403 on Wed Mar 13, 2013 11:11 am

Check your idle air sensor on the TBI. There is a setting procedure, it may just need replaced. I think your Avatar is a bit too much.
88 Cutlass Supreme Classic, Ported#6, 9.5 to 1 Olds 350, 2004R, 3.42 open for now....94 chev Z71 4x4, TBI 76 350 Olds, 5A heads,A4,204/214 cam,Sanderson's and duals, rebuilt 4L60E,3.73 gov lock, 2010 Challenger SE, Stone White, leather, 18" wheels, 2000 Dodge Dakota Sport Club Cab 4x4, 3.9 v6 and 3.92 no slip.

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tc1959
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Re: 5.7 TBI - high idle

Postby tc1959 on Wed Mar 13, 2013 11:31 am

Three things can cause what you are describing.
1. A worn throttle shaft, This can be repaired by having new bushings installed at a Carb shop.
2 the TPS or throttle position sensor is faulty or misadjusted. You need a DVOM to set it properly.
3 The Idle Air Control motor or IAC for short is faulty or clogged up with carbon. This is the most likely cause of the high idle. It is located on the side of the T-Body and is very easy to replace. it just screws in. It's a good idea to clean the port with some carb spray before installing the new one. Also disconnect your battery for 3-5 minutes to reset the computer and let the car sit and idle for ten minutes so the computer can relearn the idle.


I have no idea what a idle air sensor is. I have never heard that one before. :?
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EdontheBeach
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Re: 5.7 TBI - high idle

Postby EdontheBeach on Wed Mar 13, 2013 4:50 pm

thanks fellas - i'll try the IAC route ....and i'll change the avatar. it's not my intention to offend anyone; i thought she was funny actually.

gwhiz
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Re: 5.7 TBI - high idle

Postby gwhiz on Wed Mar 13, 2013 5:12 pm

clean the entire throttle body ou real good.i had a 91 tbi that was so gummed up the throttle plates would stick every once and a while.if that dont work look at iac valve.luckily all the sensors on that motor are cheap

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olds307 and 403
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Re: 5.7 TBI - high idle

Postby olds307 and 403 on Thu Mar 14, 2013 9:05 am

Well sorry couldn't remember IAC :roll: . I kept thinking IAT, which I knew was wrong. Either way right part, wrong name. Clean out the passage really good as mentioned.
88 Cutlass Supreme Classic, Ported#6, 9.5 to 1 Olds 350, 2004R, 3.42 open for now....94 chev Z71 4x4, TBI 76 350 Olds, 5A heads,A4,204/214 cam,Sanderson's and duals, rebuilt 4L60E,3.73 gov lock, 2010 Challenger SE, Stone White, leather, 18" wheels, 2000 Dodge Dakota Sport Club Cab 4x4, 3.9 v6 and 3.92 no slip.

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EdontheBeach
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Re: 5.7 TBI - high idle

Postby EdontheBeach on Thu Mar 14, 2013 12:03 pm

the new IAC did it fellas. Thanks a Lot!!

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tc1959
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Re: 5.7 TBI - high idle

Postby tc1959 on Thu Mar 14, 2013 12:05 pm

EdontheBeach wrote:the new IAC did it fellas. Thanks a Lot!!

Glad to hear it. I bet your car is a good runner with that TBI set up. 8)

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olds307 and 403
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Re: 5.7 TBI - high idle

Postby olds307 and 403 on Thu Mar 14, 2013 12:49 pm

Very cool. Your Avatar as a joke was fine :). The TBI is a very good set up.
88 Cutlass Supreme Classic, Ported#6, 9.5 to 1 Olds 350, 2004R, 3.42 open for now....94 chev Z71 4x4, TBI 76 350 Olds, 5A heads,A4,204/214 cam,Sanderson's and duals, rebuilt 4L60E,3.73 gov lock, 2010 Challenger SE, Stone White, leather, 18" wheels, 2000 Dodge Dakota Sport Club Cab 4x4, 3.9 v6 and 3.92 no slip.

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EdontheBeach
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Re: 5.7 TBI - high idle

Postby EdontheBeach on Thu Mar 14, 2013 3:47 pm

looks like i jumped the gun - i took the car out to run a few errands, within 5 mins. of leaving the house it was back to it's old way. 1200-1300 for 30-40 seconds when i come to a stop.

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