So im finally down to being stuck with 2 puzzling codes.. its a 93 f150 5.0, I had a code 34 2 wks ago replaced the sensor on top of the EGR it went away, I redid the vaccum lines code 33 went away for a day then came back so i replaced the EGR and after 2 days now i got code 33 and 34...?? So what gives here am i missing something?

 

When were these codes displayed? KOEO, CM or KOER

 

KOEO for 34 and CM for 33

 

34 tends suggest the valve isn't moving.

33 tends suggest the valve is part open when it should be fully closed.

 

you check the vacuum canister? (coffee can). no rust holes?

 

You should recheck your vac line work, EVR must vent to atmosphere to allow the EGR valve to close when the computer turns off the EVR to do so.

If you have the two vac lines on it reversed it would hold it open, at least until vacuum slowly leaks off allowing it to close if it at all would depend on how vac tight that section is.
Would or should also create a vac leak for the engine have trouble moving the EGR valve, again depends on how healthy the motor is how much vac it creates and how vac tight the supply is to the EVR in that condition.

 

Ill go double check vaccum lines tomorrow morning.. i did one at a time so i would get things mixed up, and no rust in the vaccum cannister. This truck is starting to really puzzle me.. but its still fun none the less haha