Engine With all smog components deleted, will that activate a CEL?

mikestang63 said:

I have Fox Body cars with both the EGR and without. It depends on the use case and never had a surging idle because of a deleted EGR
In warm weather climates, the EGR is not as important as up north for warm up
If you are that concerned about our polutting the air, then let's all adopt the crazy California laws banning gas lawn mowers, never modify or alter any of our cars, crush all cars older than 30 years old. shut down all coal mines, and everyone drive an EV right? lol . You do realize half the states have no emissions testing for decades yet have clean air and water vs. the states with the most regulation, and that Europe, China, and all other industrialized countries pollute far more than we do.

Like you said, it's his car. I am giving him options.

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EGR is not for warming up the car.
Let’s give the OP accurate info.
EGR reduces the combustion chamber temperatures to reduce NOX emissions while running leaner. That can also reduce pinging under partial throttle load. It shuts off at full throttle and at idle.

could anyone give me some guidance on hooking my EGR back up it's just not running right so I have a brand new EGR plug I'll have pics and a EGR delete plug but the resistors have to be put together in a triangle and the one I have looks like it plugs in I'm not sure till I figure out this EGR to work or go back to the delete plate if anyone can help me put this together or I watched the video of the guy splicing into the harness I'd rather plug this part in

mattys91gt said:

could anyone give me some guidance on hooking my EGR back up it's just not running right so I have a brand new EGR plug I'll have pics and a EGR delete plug but the resistors have to be put together in a triangle and the one I have looks like it plugs in I'm not sure till I figure out this EGR to work or go back to the delete plate if anyone can help me put this together or I watched the video of the guy splicing into the harness I'd rather plug this part in

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

EGR System theory and testing

Revised 29-Sep-2013 to add code definitions for EGR sensor and EVR regulator.

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. It does this by reducing the amount of air/fuel mixture that gets burned in the combustion process. Less air from the intake system means less air to mx with the fuel, so the computer leans out the fuel delivery calculations to balance things out. This reduces combustion temperature, and the creation of NOx gases. The reduced combustion temp reduces the tendency to ping.

The computer shuts down the EGR system when it detects WOT (Wide Open Throttle), so the effect on full throttle performance is too small to have any measurable negative effects.

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.

The resistor packs used to fool the computer into turning off the CEL (Check Engine Light) off are a bad idea. All they really do is mess up the data the computer uses to calculate the correct air/fuel mixture. You can easily create problems that are difficult to pin down and fix.



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. A defective or missing sensor will set codes 31 (EVP circuit below minimum voltage) or 32 ( EGR voltage below closed limit).

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. A defective EVR will set codes 33 (insufficient flow detected), 84 (EGR Vacuum Regulator failure – Broken vacuum lines, no +12 volts, regulator coil open circuit, missing EGR vacuum regulator.)


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 the engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

If the engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

If the 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


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.

my biggest issue is I know knowing about these cars I need a picture book of real cars with lines ran since I know nothing about my car besides things I was told

mattys91gt said:

my biggest issue is I know knowing about these cars I need a picture book of real cars with lines ran since I know nothing about my car besides things I was told

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Watch the videos in the thread. In the 2nd 1, Instead of cutting off the plug and wiring it you are just making the same connections as a plug in adaptor with the parts you have pictured. Pin the plug in connect how he wired his harness in the video....

mikestang63 said:

I have Fox Body cars with both the EGR and without. It depends on the use case and never had a surging idle because of a deleted EGR
In warm weather climates, the EGR is not as important as up north for warm up
If you are that concerned about our polutting the air, then let's all adopt the crazy California laws banning gas lawn mowers, never modify or alter any of our cars, crush all cars older than 30 years old. shut down all coal mines, and everyone drive an EV right? lol . You do realize half the states have no emissions testing for decades yet have clean air and water vs. the states with the most regulation, and that Europe, China, and all other industrialized countries pollute far more than we do.

Like you said, it's his car. I am giving him options.

Click to expand...

Tell me about it. Getting harder to find a smog shop to do the older cars. Most here only doing 2000 and up cars. I think most don't even know what smog equipment is on older cars so they don't bother. Even if the car passes smog the visual test could fail it.

Don't get me started abut the EGR valve and the EPA (1977 mandate)(all cars will have one)
Just like PCV in '67
That's why your car runs like chit when you disconnect the EVP or put a bb in the EGR vacuum line
Same with TAB and TAD you muck with those systems and the processor might stick your timing at ten degrees and leave it there
Best bet is to leave all that chit hooked up and work around it if you want to go racing
His 54 I would leave the light in the circuit and just let it blaze
I would do the egr delete if such a device exists and it works
Otherwise just hook it up with a functioning EGR and wait for the port to plug up or install a washer in the pipe

By the way boys
Oxides of Nitrogen cause photochemical smog
The EGR by cooling down the burning mixture lowers these
That's what they told us in Screwell anyway
HC's about the same on the air
Carry on

manicmechanic007 said:

By the way boys
Oxides of Nitrogen cause photochemical smog
The EGR by cooling down the burning mixture lowers these
That's what they told us in Screwell anyway
HC's about the same on the air
Carry on

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I'm just trying to get the EGR to work that was the only reason I took it off so I'll post a few pics so evr is plugged in red wire on left and brown/pink on right,now top evr to back of manifold and the other to EGR and fpr goes to back of manifold am I missing a line?

Well the green one goes to the egr valve
Red is manifold vacuum
It goes all over but in your case to the FPR or the EVR check the veci

manicmechanic007 said:

Well the green one goes to the egr valve
Red is manifold vacuum
It goes all over but in your case to the FPR or the EVR check the veci

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I think it's working I took it for a ride and it was at idle ok and had power and where's the veci I'll look it up

manicmechanic007 said:

Well the green one goes to the egr valve
Red is manifold vacuum
It goes all over but in your case to the FPR or the EVR check the veci

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is it the sticker? I don't have it on the car I have a picture of it

Yes, the sticker with the vacuum schematic and tune up info