OK so I have a problem properly diagnosing why I am not getting vacuum on line #16 at the EGR Valve.

The following are all things I have done so far.

1. Checked for Battery Voltage at Control Box plug to EGR Solenoid Valve's Blk/Yel wire & Ground with key on and engine off. Results = I have 12v+ at Blk/Yel wire.

2. Checked for Vacuum while car is running at idle by Supplying power to EGR Solenoid Valve's Blk/Yel Wire 12v+ & Red Wire 12v- . Results = I get about 5 in. or more of vacuum at idle and vacuum increases with RMP's respectively while supplying power to the EGR Solenoid Valve.

3. Checked the EGR Valve to see if it holds Vacuum. Results = It will hold vacuum all day long. No leak in the Diaphram.

4. Checked Vacuum lines for leaks From line #24 at the Intake Manifold to the EGR Valve line #16. Results = The complete EGR Vacuum Line Circuit holds Vacuum with out leaking. Initially this vacuum circuit leaked at the lines coming from the EGR Solenoid to a Round UFO looking thing which connects to both the EGR Solenoid Valve and Line #24. It had some white corrosion on the inside of the lines. I cleaned the inside of the lines w/a Q-Tip dipped in Carb Cleaner and snipped 1/4" from each line to make a good tight fit when reconnected to resolve the leak.

5. Checked for vacuum at EGR Valve line #16 at idle and at RPM's up to 3000+ Results = There is vacuum for about 1 socond in line #16 at EGR Valve when the engine's RPM's are reved above idle. This will be repeated for every instance the RPM's are reved above idle.

I have not Tested to See if the Vacuum will sustain under any load while in gear and driving. Nor have I tested the Electrical portion of the EGR Valve Position Sensor as I don't know how.

Additionally I would like to know how to Test the Air Temperature Sensor and the EGR Valve Solenoid.

Thank you.

 

As I said in my other post, the manual I have for the 4th gens....well "sucks". My "off the wall" thought tonight, if the system is not going into closed loop.....try testing the ect.....sorry all I've got. I'll see what I can find and post back.

 

The EGR only opens under certain load conditions, the best way I could tell you to test it;
A Helper you can trust in the car, engine warmed up fully [cooling fans have cycled] hook up a 'T' to the valve and vacuum gauge.
Have the helper hold the brake firmly with parking brake on also, put the trans in drive and bring the RPMs up thru 1700-1800. You should see vacuum on the gauge.
If the EGR ports are plugged up you will also have a lean burn engine stumble at this point.

 

Thanks Guys.

Forgot to mention I also completed the EGR Port Cleaning and the car now stals almost instantly at the slightest hint of vacuum to EGR Valve while at idle.

Also ran a few more tests yesterday which kind of has me thinking the problem is related to the EGR Valve Positioning Sensor.

I ran the T at the EGR w/the Vacuum guage sitting on the windshield and took it for a drive under load at 15mpr and 25mpr just as the smog stations do and I get the same results. vacuum starts to build and drops off almost as fast as it starts with any RPM above idle.

So w/that in mind I unplugged the EGR Valve Position Sensor 3 wire plug and drove the car again. Guess what, The EGR seems to hold steady vacuum for a little while until the ECU Detects no signal from the EGR Valve Position Sensor then the vacuum stops and the ECU throws out a check engine light. Does this seem normal and does it sound like I found the problem?

Does any one know if there is a for sure way to test the EGR Valve Position Sensor for defects or malfunctions by using a cheap Digital Multi Meter?

Poorman how do I test the Engine Coolant Temperature Sensor ? I replaced the Sensor w/a new aftermarket one when I did the Head Gasket Job.

thank you.

Tony

 

The ECT is a "range" type of thing. When warm, cooling fans have cycled, the resistance is to be between 200-400.

Then on the wire side, the YEL/GRN should have ~5v to ground? Then the same should be true from the YEL/GRN and the BLU/WHT wire.

THIS IS YET TO BE CONFIRMED!-doing research still
There is a CVC chamber (at least in the POS manual I have)= constant vac chamber-or something like that. That is why I was asking about the vac to the valve or solenoid, if it is leaking then you would loose the vac to open the valve-or the solenoid then the valve......so bottom line, one vac line to the solenoid should have vac, then when the solenoid opens it will be applied to the valve.....again, still looking.

EDIT: Trust me if I could find 6-26 I would post it.....

 

Thanks for the diagram. Now I know what all those other things in the Control Box are.

 

Ineedhelp,

Checkout my posts "90 Accord EX failed smog". I had similar issues with my EGR system. As Honda dude mentioned, The EGR will only receive vacuum under certain loads. I did not read vacuum in park above 1800 rpm. Only when I road tested with vacuum gage connected to a tee at line #16.
Even then I only read approx 2-3" and never the 8" as called out in the manual.
The EGR port cleaning allowed the car to pass the Calif. smog by greatly reducing the NOx numbers.

 

thank you 9DEX. For some reason the vacuum starts to build in both either in park or under a load while driving with a vacuum T installed to the EGR line #16. The problem I am having is the vacuum drops off to zero just about as fast as it starts to build resulting in no EGR functionality. I'm almost at the point of just throwing expensive parts at it but money is an issue for my retired mom living on SS. So that is not a viable option for her.

 

I had the same problem with the vacuum starting to build for a split second and then dropping to zero. I think your EGR system is OK and you are chasing your tail just like I did.
I saw in another post that you are trying to get your car to pass the high NOx readings, just like I did.

Here is what I did to get my car to pass high NOx and recommend:

1. Clean the EGR ports and EGR valve. Also verify all tune up items are good and that car is not running hot.

2. Set the timing to 15 degree.(read my prior posts).Advanced timing will increase Nox.

3. Run a bottle of G2P (Guarantee to pass) Follow bottle directions.Be sure all G2P is out of the fuel system before you test the emissions.

4. Day of smog check, run your car for at least 20 minutes to get the CAT nice and hot (conditioned). If a hot day, be sure the smog tech runs a large cooling fan in front of your radiator during the test.

My prior posts explain in detail from "failed" smog test to "passed" test.

 

Thank you 9DEX.

Although we have similar issues I don't think they are exactly the same issue because I don't have steady vacuum at the EGR Valve and I'm not about to poor some liquid miracle into the gas tank to fix an unrelated problem. My Injectors are not the issue at hand. the EGR System not functioning properly is the problem and no amount of miracle liquid in the gas tank will fix that. Please understand I very much appreciate your help but I don't believe your fix is the same as mine.