toms93lx

easy question.........what controlls the EGR vacumm switch?

dreamer1uk

The ECU controls the EGR vent and control solenoids on a modulated basis

I just saw you have a 93 Stang so your probably going to have an EGR Regulator. It works on the same basis, the ECU energising the EVR solenoid.

toms93lx

so does the EVR send the voltage to the vacum switch and where is the evr?

toms93lx

ok i found out that the egr vacum switch and egr vacum regulator are the same things.......so what i am thinking now is i have a bad computer.......becouse the computer take the O2 signal and uses them to adjust the egr vacum switch......so now i need to figure out how to see if my O2 signals are making it to my computer and if they are why its not making it to my egr vacum switch .........i know i have the 3 wire O2's and i checked them for a ground and they have a ground (should it have a ground all the time) i think it should becouse the other two are for the signal ....... i do need to test the coil on the egr vacum switch (god i hope its bad)

how do test the signals from the O2 to computer
then from the computer to the egr vacum switch?

toms93lx

and whats the resistance on the egr vacum switch

MustangBradley

Do not buy a computer. Buy a shop manual. That will show you what you can do to troubleshoot your problem. In the rear of the book is a wiring diagram that will show you how the sensors are wired. You have to determine the problem before you start spending big bucks. You are guessing the problem is your EGR or the computer. I run without an EGR and my computer shows all of the related codes of a disconnected EGR. I do not have an idle problem.

mjr46

o2 does not control whether or not evr is active or inactive..............egr is present at light throttle/accel/ light cruise speeds, one input that ecm strategy needs to see is tps amongst a few other input....lets start over....WHY are you troubleshooting EGR???? DID YOU HAVE A CODE FOR IT?? IF SO WHAT CODE????......your current conclusions you have drawn are wrong

toms93lx

i get codes 84, 41 ,91...........ford told me that the 41 and 91 are irelivent and caused from something else and the the 84 is from the egr vacum switch...they also told me that the O2 sensors control the vacum switch....the vacume switch is not switching at all. if i unhook it i get the same codes.......everything else has been tested and works.....i am thinking its the O2 signal thats f-ing it all up .......oh and i dont want to buy a new computer unless i have too.......i have a hanes manual for the car but it doesnt go to indepth with this .....i have the wireing diagrams but it doesnt tell me signals ....doesnt tell me what i should get and where i should get it

mjr46

purge your mind of what some ill informed person at ford blew smoke up your ****.........o/2 does not control egr selonoid!! it is an input to the ecm, you currently have o/2's that are indicating a lean condition, you need to trobleshoot that, looking for vaccum leaks, weak fp or restricted filter, or bad o/2 ground to intake, dirty maf...ect..ect......as for the egr selonoid the ecm controls the ground to it IIRC, have you checked for power on the power side to selonoid?? have you pulled the selonoid and manually applied current and ground to it to see if it operates ruling out a bad selonoid, have you checked for continuity on the wiring back to the ecm by doing pin out tests from the ecm connector out to the selonoid harness connector??? have you T-ED in a vaccum line to the egr vaccum line to see if indeed there is no rise on a vaccum gauge when the KOER test triggers the egr portion of the test???......my guess you can't answer yes to all these questions, and if you keep thinking and going on about how the o2 controls the evr function, I can't help you....and I'd resolve the lean issue

dreamer1uk

Everything you need to know can easily be Google'd.....

O2 sensors can be tested with a DVOM as they work on a 1VREF. You will need a wiring diagram to see which is the SGN RTN and GND.
The ECU only uses the O2 sensor(s) in cloosed loop. They are used to control air/fuel mixtures from the comands last sent to the fuel injectors. Open loop is when the ECU uses other sensors to help determine the fuel control mixture.

And as i stated in your other post, codes 41 and 91 could be caused by a vacuum leak (lower intake manifold for one)....

Did you even do a voltage drop test of the feed and ground side of the EVR circuit to rue out any wiring issues?....probably not... did you test the solenoid by jumering it?....probably not.

Search and Google are your friend

And mjr46 beat me to answering your post