Toyota Camry 2000: Odd Coughing when starts

Question

Recently, I notice that my car begins coughing couple minutes after it starts. It have happened since Jan, 2012. First, I thought it might be due to Winter since it is cold weather.

However, it still occurs now so I drive my car to our mechanic guy. We guess it might be a problem from transmission. It shakes like when you're on driving mode and you hit brake to stop your car (like waiting for red light). He checks the transmission but it seem to be ok. But he didn't see the shaking when I was there. Since the shaking is only about 10 min after first start of the day. I drove to his garage is about 20 min away.

I changed my spark plugs and their wires the whole set two years ago. I also change engine oil regularly. And no sign of any leaking on my parking spot. Transmission oil is in good level. My Camry's engine is 3.0L V6.

Any one have any idea what causes the problem is. Thanks.

Answer 1

It sounds like a small misfire problem.

Perhaps an intermittently failing sensor (specifically, when cold). I would check and test any intake air temperature sensor, water/engine temperature sensor, and mass airflow sensor. Any serious malfunction should show up via the check engine light, since your car should be OBD-II. If so, getting a code reader should point you in the right direction.

Otherwise, it may be a physical problem with the engine, such as low compression on one cylinder that, when warmed up, raises enough to eliminate any misfiring condition. Unlikely, but a compression test is quick and easy to eliminate this.