Well, she failed the smog test again.
This time it was for NOX emissions, and the HC and CO passed.
EGR is a technique used to lower the combustion chamber temperature, thereby reducing the amount of Oxides of Nitrogen produced.
It's a "known issue" with the 5M-GE engine that the passage through the intake manifold from the EGR valve to where it dumps into the throttle body gets plugged up.
A very simple test is to apply vacuum to the port on the EGR valve, which opens it, and dumps large quantities of exhaust gas into the intake manifold.
It should make the engine stumble ot stall, as the EGR is normally disabled at idle.
I hooked the valve to direct manifold vacuum, and I could hear and feel the valve "POP" open and shut.
NO change in idle speed or quality, indicating that the passage is plugged.
Not a terribly difficult job to do, but time consuming, and you have to do with engine COLD.
I'll also be replacing the catalytic converter, as the one on the car looks to be the original one, and after 30+ years, and 165,000 miles, it's about time to retire it!
Since I was driving on expired plates and didn't want to get pulled over and ticketed, I took the side streets to the nearest smog test place. As a result, the car didn't get the usual "30 minute highway blast" to get it FULLY warmed up, and get the converter nice and hot. A converter at the correct operating temperature is essential to get it working correctly, and an old one usually benefits from a good highway run before getting the car tested.
Hopefully a new converter and cleaning the EGR system will get rid of the vicious pass/fail/pass/fail cycle this car has been trapped in for the last 10 years or so.
And I'll also replace the distributor cap and rotor, as the one on the engine looks pretty old, and I have a couple of new ones I bought on sale at Rock Auto.
One other thing I'm considering is to put 5 gallons of lead-free, alcohol free 100 octane VP racing fuel into the tank before I take it back to get retested.
The octane requirement for these engines is only 91 octane, BUT when they were designed and built, the computers were calibrated to use GASOLINE, not some funky blend of gas and moonshine!
As far as I'm concerned, adding 10% booze to the gas I buy at the pump means I'm buying adulterated gasoline. There are a few "pure gas" stations here in SoCal, but none are close to where I live.
Luckily there's a VP distributor here in Long Beach, so getting a 5 gallon bucket is just a short drive.
One of the things about the 10% ethanol blends here in Kommiefornia is that the quality is all over the map. Sometimes the refiners will use a lower grade base stock, and ballast it with ethanol to get the octane up, and sometimes they won't.
And it's well known that 10% ethanol blended gas can damage the fuel systems on cars not modified to use it.
The whole thing is just another "feel good" program to con people into thinking "renewable energy", when we have plenty of oil in the ground here in the USA.
Of, well....enough ranting for now.
Off to the auto parts store (NOT Auto Zone!) to order a converter, and grab a new gas cap while I'm at it. The car passed the "EVAP" portion of the test fine, but the smog guy was suggesting that the old, crusty gas cap get replaced just for peace of mind, and I agree. It's just one of those things I kept forgetting to do.....