Ok.. this has happened twice to me. The first time I thought it was a fluke...

It's been pretty cold here the past couple days, in the 40's. I live in South Texas... that's cold..
Anyway, the other day I started it up,and I didn't realize my foot was on the throttle a little bit. Well, after the car fired up, it revved to about 4000 and I let go. As the needle was dropping, you could tell that it was running really rough, then the coolant light came on.. it stayed on for a couple seconds then turned off. I've never seen anything like this happen before, so like I said earlier, I just thought it was a fluke..
Well, last night, I started my car and it sounded as if it were having a little trouble starting, so when it cranked over, I stepped on the throttle a little. Again, the same thing happened, as the needle was coming down, it was really rough, and then that coolant light came on again. But after a few seconds, it turned off.
Anyone know, what this might be?

 

Add some distilled water to the over flow reservoir.

 

shot in the dark here, did you check your coolant?

 

Don't know what you mean by rough. Are you talking about when you first start your car and it's a little rough but eventually smooths out as you drive the car and warm up the engine? That would be normal, right? Or are you talking about a roughness that is not normal?

Either way, coolant light is probably not connected to the engine "roughness." A ton of owners have reported the sensor inside the plastic coolant reservoir wears out and malfunctions. The sensor is embedded into the bottom of the plastic reservoir, so if you want to replace the sensor, you have no choice but to buy the plastic reservoir (it's a combined unit), and that can be around $200. If you don't want to waste money, you can just keep an eye on the coolant in the reservoir and also monitor the temp from the cluster gauge while you drive.

On the other hand, maybe your sensor is fine and you just need to add some coolant/antifreeze to the reservoir!

Again, engine roughness at start up is probably not connected to the coolant warning light. Recently, my light went on and off intermittently for about 2 weeks. I checked the reservoir and I could see green inside so I assumed there was enough. The light would go on when I started the car and disappear when I started moving the car. It would stay off while the engine warmed up while I was cruising on the fwy, so I thought everything was fine. But then it would go back on intermittently even while fwy cruising. So, sensor light worn out, right? Wrong. Two days ago, I added 50/50 coolant/antifreeze to the reservoir all the way to the top FULL line and the light has not come back on! So make sure your coolant is all the way to the FULL line.

Or maybe your water pump is leaking coolant. If you jack up the front passenger side, you can slide under your car and look at the bottom of the water pump (metal housing) and also the surrounding area of the car. If you see green liquid, then you've verified it's a leak. If the green is right on the water pump housing, then you will probably have to replace it entirely. But if it's in the surrounding area, it could be a hose, in which case you would just have to buy a new hose or re-secure an existing hose.

 

Ok my bad guys, I knew I forgot to mention that... yeah the coolant level was full... No leaks either.

By rough... almost like a sputter.. The only other time my car ran like this was 1) when it was flooded, and the first time I started it after that, and 2) when it's been sitting for a couple days and the first time I turn it on. But it will run rough for a minute then turn to normal. The only way I could describe it, is... kinda like in a piston engine, when there is water in the spark plug...

 

If it's cold and you rev it too high the PCM cuts the ignition to protect the engine......kinda like hitting the rev limiter. It stops when the engine warms up.

 

Hmm.. I didn't know that.. thanks.

 

Mine does this too when its cold. I just let it warm a little and it goes off.