Car runs rough when cold

2000 Toyota Camry le v6

When I first start my car it runs rough after about 5 to 10 minutes it runs fine. I have no check engine light on. I used sea foam and the problem went away for a couple weeks then it came back. I have about 30k on my spark plugs. Please help

Try a full tank of premium and add two bottles of Techron to the tank.

@insightful’s advice is consistent with what you posted about the Seafoam clearing up the problem, albeit temporarily. My one thought is a spark plug wire that with the cooler weather the conductor shrinks and the resistance goes up. The Seafoam may have cleaned the firing tip of the plug enough to allow it to ignite fhe mixture. With the colder weather the conductor shrinks even more.
My other thought is that coolant is leaking into one cylinder and plug won’t fire until the,engine warms up. I had this problem with a Ford Aerostar.

I popped the hood and took a look at the engine while it was running rough. I noticed there was sparks coming from the middle ignition coil. After the car warmed up the Sparks went away. I replaced the ignition coil. I hope this solves the problem.

Ooooo…sparks not good…let us know.

You found the problem. A good time to look for ignition problems is at night. If you see sparks jumpimg, you have an ignition problem.


I remember a few years ago, one of our fleet vans was intermittently not starting and/or stalling

When it refused to start, I propped the hood so that it was almost closed, but so I could still see the wires

When I turned the key, it wouldn’t start, but because it was dark enough under the hood, I saw the spark from the coil wire arcing to ground. Sure enough, there was a hole in the insulation. I did a full ignition tuneup . . . plugs, wires, cap, rotor . . . and it’s been fine for a few years now


What does premium gas have that regular gas doesn’t?


The problem might be with the cold-start injector.

Open the hood, and on the right side (passenger side) of the upper intake manifold you’ll see the cold-start injector. That injector may be dirty or defective.


“What does premium gas have that regular gas doesn’t?”

Higher octane.

It has been a week and the rough idle has not returned. I did a road trip of about a 1k. I had no problem. So I think it’s safe to say problem solved.

Thanks for the update. It is appreciated.