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Jim Grant's Tech Tips
‘97 Chevy Cavalier, More Wet Misfire Problems
Q: I've read a few of your tips regarding Chevy Cavalier misfires and you haven't nailed it yet. In one you tell the person that it is probably plugs or plug wires, which I have replaced and other people that have complained have replaced as well. For us, you tell us to take it to a technician instead of trying to solve it ourselves. So we go to a tech who finds that there is a single cylinder misfire code, but no other diagnostic codes. Has anyone nailed this down yet? When it rains, the car starts to miss (under load) and occasionally you can hear an audible backfire in the engine compartment. The check engine light flashes a couple times then it stays on and the ETS (Electronic Traction control) light stays on. The only diagnostic response is a misfire. We've replaced the coil pack, plugs and wires. Any new guesses? Is there something with a traction/wheel speed sensor that is triggering a misfire for traction related purposes? Maybe the ignition is fine and something else is telling it to misfire!? Thoughts?
- TJ Johnson
A:
Let’s take a moment and explain why the electronic traction control which is called Enhanced Traction System (ETS) warning light will turn on when the engine computer sees a problem. The ETS system monitors wheel speed via the Anti-lock Brake System (ABS). If the ETS system sees a wheel spinning due to snow, ice, rain etc., the ETS computer sends a request to the vehicle’s engine computer to reduce torque. The engine computer responds with a combination of strategies. In the engine computer’s bag of tricks to stop wheel spin it can perform any one or combination of the following; cut fuel off by trimming or turning off fuel injectors, retard the spark timing or up shift the transmission. In the days of old we just let up on the gas pedal. Now the computer does it for you. If you have an engine running problem it is more of a problem than you realize. The engine computer is the high command center. The engine computer will work and respond to information from the other computers in the vehicle. But in the event there is a system or running problem that the engine computer is responsible for, “it will” lock out all of the other vehicle computers. If there is an engine running problem that causes the engine computer to store a code and turn on the “Check Engine” light guess what computer doesn’t talk to the others? The engine computer. The ETS computer gets all put out when this occurs and turns its warning light on in protest. So, there you have it. If the check engine light is on the ETS warning light will come on as well and the ETS system will not operate until the engine computer problem is corrected. If your vehicle is misfiring in wet weather you have to find the cause for the misfire. I still bet a coffee you have an ignition problem. In the shop we’ll use a water hose, a mix of anti-freeze and water in a spray bottle or even a mix of salt and water in a spray bottle. The ignition system will get sprayed down and the spark leak hunt will begin. You fix your misfire problem you’ll turn the ETS light off too.
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