High-Idle Problem

 

I just fixed this problem with my SEC. This was an ongoing problem for me, so I became an expert while troubleshooting. The two components that are responsible for controlling idle speed are idle air valve which is located near the distributor and upper radiator hose. It has two large vacuum hoses (3/4 or so) and a plug with two wires. The electronic idle control unit is placed on the firewall and is a small 4" by 3" black box to the right of the larger control unit with a large plug. You cannot confuse the two, our man is the smaller out of the two.

As some of you already know, 9 times out of 10 it is the electronic control unit, and not the air valve that is faulty. However, what I recommend doing is taking the valve out and cleaning it thoroughly. It becomes quite dirty over the years of use. I soaked mine for 4 hours or so in carburetor cleaning solution. Maybe someone might contribute a better cleaning method. To isolate the problem, make sure that the valve works by installing it back in the car after cleaning it and feeding auxiliary power to it while the car is while the car is at idle. If the engines starts to die out after manually closing the valve with auxiliary power, they valve is functioning. I also done this: before I installed the valve to make sure the piston was moving freely.

If the above steps were completed successfully, it is the electronic control module that is at fault. Take the module out of the car and pop off the cover. It can be removed by prying the six clips to the outside and sliding the cover off. Inspect the circuit board for burned components. Note: the transistor mounted to the top left may have a burned spot on the back of the board, but it is due to the high temperature the transistor reaches. It has a heatsink, and most likely it is okay. Most what you want to look for is broken solder joints on the back of the board. Might be hard to see, so put the unit back in the car without the cover, connect it and start the car. Then start playing with the unit like you are a 7 year old child. Bend the board back and forth slightly and see if the idle speed changes. If it does, try to isolate the area where it seems to be problematic, if not, you might have a bad components on the board. In this case you buy a rebuild one ($80-$125) or a new ($200-$300). Mark the area that seems faulty and remove the unit from the car. Inspect the area with a magnifying glass (on the back of the board mostly), and look for solder joints that seems to have a circular crack around the base. Resolder these. I've resoldered about ten joints on mine. After you corrected as many as you can find, put the unit back in the car and follow the same procedures until you got the fix. I had to do this several times because stuff is so hard to sometimes see on the board. Who knows, maybe it might be a simple visible problem for some of us. This is what solved the problem for me, and I wish the same luck to everyone.

- Contributed by Serge Maskalik

<- back