MKT

Had the check engine light and the code told me it was an EGR issue. The car, a 92 Honda Accord wagon with the 2.2 and almost 270K miles runs strong and mileage is still between 25-26 mpg at 80+MPH.

Given the mileage I figured the EGR ports were coked up and causing the CEL. Today I pulled the port plugs and they were pretty plugged up, a bunch of Berryman's B-12, compressed air and careful cleaning got everything open again. Car ran a bit rough until the fuel evened out and it smoothed up and purred. As soon as I kicked it up off idle I got the CEL again. Cleared the codes and tried it again and the same thing happened.

I put vacuum to the EGR valve while idling using my mighty vac and the car shut down immediately. It didn't stutter/shutter to a halt, it shut down as if turning the key off. That checks good. Next I turned to the vacuum supply line for the EGR. At idle I have no vacuum, at speed I have no vacuum. I checked the power at the 4 pin connector and have 12+ volts, jumping the +/- does not cause any vacuum increase.

I have a spare control box and did a quick swap and retested with the same results. Unless both boxes have bad EGR solenoids my problem has to be elsewhere. Where do I look next?

phootbag

So, you manually activated the control solenoid? Do you have vacuum going TO the control solenoid?

MKT

I did not check vacuum going to the solenoid. Which line supplies the vacuum?

I'm done with the car for today but will look at back tracking the vacuum deficiency. I think I'll spend a little time reading tonight.

bdmlilburn

there is a constant vacuum box that is also part of the system. its the white and green thing. though if you tried two different ones i doubt that both of them are not working. check all the vacuum lines that go from the intake manifold to the constant vacuum to the egr solenoid and then to the egr valve.

the egr valve itself could be bad and not opening. have you taken it off and cleaned it? it could be so dirty internally that when its shut the vacuum from the solenoid is not enough to open it. before replacing it remove it prop it upside down and fill it with brakecleaner and let it sit for a little bit. also manually operate the diapram while its soaking so the cleaner gets everywhere.

MKT

I took the EGR valve off while cleaning the EGR ports. Cleaned the "pin" and checked for free movement everything moved freely. Applying vacuum to the valve with the engine at idle kills the engine so that should indicate the valve works. I completely emptied a large can of Berryman's B-12 cleaning the ports and EGR. Also used a little to clean the injector surfaces too.

I opened the spare emmisions box to study the lines trying to see what could be common between the two to cause both to not have vacuum under load. I'm thinking I'll need to check the vacuum ports on the throttle body to make sure all are pulling HG.

MKT

OK,
I checked vacuum on the three ports coming from the throttle body. Two are pulling 15" HG and the third, the line that provides vacuum to the EGR solenoid is pulling 8" HG. Since the book calls for vacuum to be pulling 8" off idle it sounds like the proper amount of vacuum is getting to the solenoid.

I tried two emissions boxes, neither worked and I find it hard to believe both would have a dead solenoid. What else in the electrical side of the system could be preventing the solenoid signal?

I think the only other electrical component is the EGR position sensor, is that correct? Could a dead position sensor cause the solenoid to not open? And, last question, is the position sensor replaceable separately or does the entire EGR valve/sensor need to be replaced?

Even though the EGR is not functioning, since cleaning out the ports I noticed the engine is turning about 200-300 RPMs slower at highway speed ~80 MPH now showing 3200-3300 RPM where before it was steady at 3500.

MAD_MIKE

That can be hard to confirm, it could be lockup from the TC, or simply the inaccuracy of the stock tach. Sometimes it does not always read accurately.