Mechanics

HOW DO I GET IT TO IDLE SMOOTH AND PASS SMOG?

1990 Ford F-150 • 180 miles

4.9l 5speed 4X4 duel tanks did tune up and replaced fuel pressure regulator. Still is idleing too rich and has a missfire at idle.
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FreAkytOasTer777
May 5, 2012.



Look for vacuum leaks. Is the check engine light on? O2 sensors were common back in the day. Map sensors were issues as well. All need to be verified by a shop with a scan tool.

Roy

Check engine light is on steady, I checked seld diagnostic and codes "31" and "67" are flashed Would the evp voltage being low (code 31) make it do that?

Tiny
FreAkytOasTer777
May 5, 2012.
Not really unless it is pulling raw fuel from the tank but not likely. You need some help here unless you have a scan tool

Roy
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Ok, thanks for your help

Tiny
FreAkytOasTer777
May 5, 2012.
Good luck


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