This is topic 1987 Mustang idles rough in forum Tech Talk at Northern California Ford Owners  .


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Posted by p1mp1n (Member # 1961) on :
 
Looking at buying this 1987 Mustang, when started it idles ok then after about 45 seconds at idle it begins to jump up and down then goes back to normal? Owner said its because its originally an automatic converted to a 5 speed, the computer was never swapped so the cars getting signals from an AOD trans?

Also noticed it revs high upon start up without gas pressure?

I'm guessing vaccume leaks?

Any info would be greatly appreciated, thanks
 

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Posted by triple b (Member # 8763) on :
 
Your not a mass air car so I believe the A9L/A9P issues are not your problem. Your car should be speed density and the issue could be you vaccine lines or map sensor

[ 2013-05-16, 11:09 AM: Message edited by: triple b ]
 

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Posted by elsilerjr (Member # 12811) on :
 
mine does this randomly not often but its a 87 Speed density and i have a vaccum leak its small and does not effect anything when driving, only at idle, never dies or anything.
 

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Posted by straightliner1 (Member # 2679) on :
 
Try cleaning the Idle Air bypass valve. These get coked up with soot and start sticking. Remove it from the throttle body and spray the piss out of it with carb cleaner.

(#6 on the pic below)

http://www.cjponyparts.com/tech-fox-body-engine/a/170/
 

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