Another CA Smog thread :)

I have failed twice, both the exact same way, with a swap of H-PIPE's, so I am assuming they are doing their job, and something else was amiss...

After searching the forums, I came across a few pages with recommendations, and today I am gonna get this car at least closer to passing smog.

Here are my results:

"TEST 1"


"TEST 2"


Judging by the numbers, I think that if I switch over to 87 octane, drop the timing maybe a degree and fix my stuck EGR, that I should be set for a smog right? Anything I'm missing. I've already tested my little solenoids on the passenger firewall, and they were all good. I will get the EGR unstuck and make sure it works properly before going on first.

I am following the directions below, however I am trying to troubleshoot my EVR, can I test this using just a vacuum tester? Or should I make sure I don't have vacuum at idle at the EGR only. I tried to see if the ports would hold a vacuum using a handheld, but neither port holds anything. It sorta vents through the top. Does that mean that the EGR isn't supposed to get all 18+ in of vacuum, and attempting to do so may damage my EGR during testing?

I guess I'll go over this all again, and make sure my Stuck EGR was the only thing.

The directions I grabbed from one of Jrichkers (?) posts.

EGR System theory and testing

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.


Click the image to open in full size.

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)
Click the image to open in full size.

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.

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid.



EGR test procedure courtesy of cjones

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 or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

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 EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
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 the EVR has failed

EGR test jig
Click the image to open in full size.

To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.

Late Model Restoration may still have 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/...0 1&comp=LRS for more details

I found that out after I took it apart

My question is, I am pretty sure that fixing the stuck EGR would definitely bring the NOx down to within spec, but would that also bring the HC down a bit? Or should I try another trick on that? I can't afford to keep taking tests, I've already done these two.

Yeah it should be the EGR first. Otherwise its a super Lean condition that causes the high temps in the combustion chamber, or too much advance on the timing. At least thats what I gather from all the sites I've picked on all day.

You'd be surprise how easy it is to clean also, just as long as the diaphragm isn't messed up, and holds vacuum it should work just fine. I am going for a retest tomorrow, will let you guys know how it goes. I just hope that the HC comes down a bit now that the NOx should fall drastically. Since I have ruled out the Cats.

Shaolin Crane said:

Just to let you know the reason its so hard to pass this year is they cut the allowable HC in half. I got a guy if you need one.

Click to expand...

Yeah but is he in the other desert like you? Thats quite a drive, then again, it may be worth it. I'll be heading to the sniffer in a few, I will try out the balance test in a bit, but where would I hook up a light, my check engine light doesn't light up when I run the tests...

ALSO: when the car does its EGR tests, am I supposed to see the diaphragm move on the EGR valve? I just want to make sure its all working. It is getting vacuum, and is holding a good vacuum for the EGR (between 5-10).

one more question... Would my MSD be causing any problems on the low speed tests? I would think that the MSD would help by sending the multiple sparks in the sub rpm range, but I don't think I had it connected in the last smog I got.

The Balance test gave me back a #9 after running three times straight.

Will be going in a bit, just need to know if my MSD might be better disconnected for this test?

Ok, ran the test codes again,

KOER - *Correction
94 - TCC/AIR system
44 not 4 - Thermactor fault
33 not 3 - Canister or EGR system Fault.

*Now I'm going to dump these and see if I have the same problem, or if these were just stored codes.

KOEO
85
82

Now to clear the codes, what do I do again?

Ok, I just took a video of the EGR during the EGR test, and it did not move AT ALL. I've gotta check fuses, and power to these valves next, what do you guys think, maybe it didn't move much if anything, because there is quite a difference from 0in of vac to 8in of vacuum on the diaphragm

Anyone know about the MSD and low rpm HC emission?

Okay, now I just tested the vacuum at the EGR, I had a T coming from the EVR, the EGR, and to my gauge. Am I supposed to read something like that? somewhere around 5-10in when the EGR is turned on? Or am I doing this right. I'd hate to spend another $40 for nothing if this egr isnt doing what its supposed to.

At idle there is no vacuum (normal)
After running the EGR test using the jumper there is no change in vacuum.
Nothing either after whipping the throttle a few times. Does this mean the EVR is bad?

I am testing my EGR Position Sensor right now, and I am getting no resistance reading between ANY of the pins, so I think I found why my sensor doesn't show movement at all

I am going to the parts store to verify with a new part, and we will go from there.

Hmm....

No go on the EGR sensor, I went down and tested the leads using a backprobe and the KOEO to get 5vRef, grnd, and a perfectly good signal going from .5v up to 5v when plunging the sensor. Even going slowly, the device seemed to not have any broken area of reading.

Now then, to test my EVR, I have ohm'd out the coil it read 42, which is within spec. It is getting full vacuum on the bottom hose from manifold, and not giving any vacuum at idle. It does read 12v on the positive wire with KOEO. And when I jumper it, what should I be looking for?

Ok, I've jumpered the EVR to a test battery have, and I figured that if I suck on the EGR supply port (with a hose) and tap a switch that supplies power to the EVR so I can see if it even does anything, and sure enough, it restricts air to that EGR, at least enough to move the diaphragm. I am going for my smog now, Wish me luck fellas!