White_96_GT

Hi Everyone,

Just joined and I am in need of some help. I have searched this topic and most forums come back with things I have already fixed and tried.

I have a 96 GT that failed emissions here in Colorado last week. I replaced one faulty O2 sensor (bank 2 sensor 2), put on new EGR valve, EGR control selonoid and DPFE. Now the car runs really rough at idle, and will about die when I come to a complete stop. Throwing code p0402 (excessice EGR flow). What else could be causing this? If I remove the line from the control selonoid to the EGR valve it runs just fine.

I've had the car for 7 years and never had this issue.

Any help would be greatly appreciated. Thanks!

uberstang1

Could be a problem with vacum, the black vacum solenois could be giving you an issue. Check all your vacum lines.

cliffyk

Here are the possible causes for P0402 from the shop manual, work the list from top to bottom.

My grandfather was a stationary steam engineer, he always told us that "The last time any machine started up and operated correctly may have been the last time it starts and operates correctly."

I.e. that you have not had this problem in seven years is precisely why you are having it now...

White_96_GT

I appreciate all the feedback, here are the solutions I pulled from cliffyk's post:

EGR valve stuck open - new egr valve
Plugged EGR vacuum regulator solenoid vent - new solenoid
Plugged EGR tube - have vacuum
Slow responding D.P.F. EGR sensor - new DPFE
Damaged DPF EGR sensor
Improper vacuum hose connection - all hoses are running correct
Plugged vacuum hoses - no plugs that I know of
EGRVR circuit shorted to ground
Damaged EGR vacuum regulator solenoid
Damaged PCM

All parts related to the EGR system are new. The vacuum is there, I can feel it when I take it off of the EGR valve.

Is it possible I just need to put more miles on it and let the car readjust? I know Ford has a recommended pattern to drive to reset OBDII, and I have that.

How do you guys recommend checking vacuum? My brother in law is coming over tonight and has been a mechanic for 18 years. I like bouncing ideas off of other people to see if my head is just stuck in one place. Thanks again!

cliffyk

The EGR tube is unrelated to engine manifold vacuum, it is the tube (#5, yellow, below) that runs from the drivers side exhaust manifold to the EGR valve and which has the ports to which the lines to the Differential Feedback Pressure (#1, red) sensor connect.

White_96_GT

Awesome man I really appreciate your help. I'll look into it tonight and get back to you.

school boy

hey white, if youre in need of the #1 box, let me know. i deleted my egr and have no need in it. pm me in the feature if yours is bad.