Matthewdbaker

Whe I put my 1993 f 150 5.0 into park it idles up and down 3 or 4 times. It does it most the time but not all the time. I checked for vacuum leaks and couldnt find any, and I replaced the EGR and o2 sensor. Any ideas anyone?

Matthew Burr

no codes? maybe check even without the CEL on.

check your IAC, TPS, fuel pressure.

EGR only affects airflow when driving down the road, not at idle. sounds like the computer is getting feedback from the O2 sensor, thats why it ends up correcting the idle, but something is causing it to have to adjust the idle.

Matthewdbaker

It's shooting code 33. And brand new o2 sensor

Matthew Burr

hrm code 33 is egr... maybe the return pipe is busted somewhere

1995F150BlAcK

Have you checked to make sure all the cylinders are firing? I know if it is misfireing the rpms will rise and fall a little bit.

Crownman

To do a good check to see if its the egr causing the issue try this. Cut a piece of aluminum out of a can, punch two holes in it to line up with the egr mounting bolts. Then unbolt the egr and slide the aluminum piece in there to block it off. Bolt the egr back down and then see if the problem is still there.