Cleaning the EGR port
September 9, 2010 10:54 PM   Subscribe

How should I clean my EGR port? The check engine code says "inadequate flow through the EGR valve."

I have a 1997 Saturn SL-2.

I have tried two ways: 1. Mechanically by running a speedometer cable (attached to my drill, end of the cable intentionally frayed) through the port between the EGR valve and the air intake. I took the throttle body and EGR valve off and ran it through from both ends of the port. This didn't help much.
2. Chemically by putting the throttle body back on and spraying a whole can of Chemtool throttle-body cleaner spray into the suction of the EGR valve attachment flange. The engine was running and the Chemtool made the engine stutter a lot, so it was getting the whole way through the system.

After the above treatment, I reset the check-engine light by disconnecting the battery for a while. The light came on after about three days of driving.
I guess the check-engine light may be indicating some other error code, but probably not.

The EGR valve seems to be working as the valve opens when I apply a 9V current to the outside poles of the valves electrical connectors.

TIA
posted by noonknight to Grab Bag (3 answers total) 1 user marked this as a favorite
 
The chemtool is not going to bust thru hard carbon. And, if the car is going thru a lot of oil, this can accelerate EGR valve probs even after a few days.
You may not have gotten all the carbon out (smart speedo wire idea), but I would first have that code checked (not sure if you can do this yourself on a 97, but many places will run the check for free for you). Then, if the EGR valve is indeed the issue, check the elec connections with vmeter, and use vacuum to check if the valve is ok.

(or replace for about 60-80 bucks).
posted by artdrectr at 11:39 PM on September 9, 2010


There's a brand of brushes called Bench Buddy that I use for stuff like that.
In addition to making sure the valve works, it's also important to find out if the other inputs for valve operation are functioning correctly. If it's an electronic valve, does it have a good ground? Is the signal from the PCM present? If it's electronic, the EGR valve may have a position sensor that should be functioning. The best way to test this is to use a scan tool to command the valve while the car is idling. The car should stall if the EGR system is commanded at idle.

Also, if the problem persists after cleaning the ports, keep in mind that the computer monitors EGR flow by looking at other sensors, but not at any dedicated EGR flow detecting device. Depending on the set up, EGR activation is determined by observing a corresponding drop in the Mass Air Flow value or a rise in the Manifold Absolute Pressure value. If either one of those inputs is faulty, it's not uncommon to chase ones tail when diagnosing an EGR malfunction. This is why it's best to diagnose a car based on more than just the trouble code.
posted by Jon-o at 3:11 AM on September 10, 2010 [1 favorite]


You should especially target the buildup around the lip/seat where the valve sits when closed -- if the buildup causes that resting position to read too high on the position sensor when the computer hasn't commanded the valve to open, it will report an error because it thinks the valve is open when it's in fact closed (but sitting higher than expected.)
posted by Rhomboid at 5:39 AM on September 10, 2010


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