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1989 ford f-150 idle problems

james1978

james 1978
1
0
hello everyone new guy with problems 89 f-150 5.8ltr. after engine is warm in park idle drops down so low almost dies then something happens and idle goes back to normal. back ground on engine: new overhaul in 2005 .060 over pistons, mild cam, long tube headers, all new inj. new pumps in tanks and new pump on frame. engine runs real strong. problem just occured last few days changed fuel filter still no help no check engine light on no codes when using scan tool. any suggestions would be gladly appreciated.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
Sounds like you have a classic case of needing a TV cable adjustment...assuming you have the AOD. I had the same problem in my 87...all roads pointed towards the TV cable...brought it to the local shop...they worked their magic...good as new.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
Oh yeah...pardon me. Welcome to the site. Chris had a good suggestion with the IAC...it will have similar symptoms...but I'd put my money on the TV cable.
 

blacksnapon

Moderator
Staff member
When you upgrade the camshaft, many times the duration creates a large overlap that also decreases available vacuum. Because the idle speed is set by regulating the vacuum, you need to be especially concerned about any vacuum leaks. The IAC motor has to be working properly as well.
 

89frankenford

Grabber Green Consultant
4,547
147
NH
welcome to the site! yeah i would say check the tv cable and the iac, the iac should be on the throttle body somewhere, it has a 2 plug connector going to it, i would pull it of and check to see if it is clean and spins free
 

flareside_thunder

Florida Chapter member
7,812
246
Could be MAP sensor as well...it's mounted on the firewall next to the ac/heatercore box...try the previous two first...no sense in throwing parts at a problem that just wastes money! :)) Welcome to the site!
 
973
11
I had the exact same problem on mine, only mine eventually started to die out... my IAC was stuck. I replaced it and the problems went away.
 

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