Quick test of EGR??? Buy a new one?

i tested the valve by taking it off and sucking on the small inlet tube enough so it pulls the bag inside and holding it there with my tongue over the tube. My held up with no fall. I replaced my sensor just for the hell of it. Never had any problems. I know it sounds gay but hey it works.

ok car is on idle take some thing small but cant but a hole in ruber and the holes on the egr you should see the diaphram push it in, IF THE CAR STUBLES OR IDLE GOES OFF THE ITS GOOD , if idle stays the same the its bad.

good day

S Some basic theory to clarify how things work is in order…

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.



Troubleshooting:
There should be no vacuum at the EGR valve when at idle. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)


The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt.


EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 2-5 in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM.
should read about 2-5 in vacuum


Late Model Restoration has the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=M12071N302 1&comp=LRS for more details

I also have a code for egr. Just for the hell of it, I replaced the valve and sensor. Still have the code on a key on engine on test.

strtrcr50 said:

I also have a code for egr. Just for the hell of it, I replaced the valve and sensor. Still have the code on a key on engine on test.

Click to expand...

Codes 31, 32, & 35 can be wiring problems, so create your own post with your code results and I will try to help.

bloopbloob said:

i do have vacuum at the hose entering the egr valve at idle. the lines are all connected properly. besides incorrect lines, what else could be bad?

engine does not stumble, vacuum only draws air, no vacuum is created. when i push the diagphragm manually, the engine does stumble. what would this mean...?? i assume a vac leak in the egr valve...

so does this mean i have 2 problems causing the code? a bad evr AND bad EGR valve???

Click to expand...

most likely, yes, if you have vacuum at the EGR at idle then the EGR Vac Regulator is either bad or getting a bad signal from the comp.

appling vac to the EGR Valve at idle and EGR not opening shows bad EGR Valve (unless you have a BackPressure EGR Valve, which you don't you have)

Do I need the vacuum line attached to the EGR? Currently there is no line running to mine. Is it better to cap off that end or run the line? Will either hurt performance? Thanks

dls322 said:

Do I need the vacuum line attached to the EGR? Currently there is no line running to mine. Is it better to cap off that end or run the line? Will either hurt performance? Thanks

Click to expand...

Go back and read my first entry on this post. It explains how the EGR works and what it does. Anytime the Check Engine Light comes on, the computer is operating in limp mode, which means reduced performance.