Rep Power: 811

Okay, this has been eating at me for a long time now. So here's the situation. I have a relatively stock car (check my profile for details), and it always seems to feel different every time I drive it. Some days it will drive really well. The engine sounds like a champ and everything feels faster and good. Now other days the engine starts making growling sounds and the car feels like there's no power. Sometimes it doesn't start well and continues to run crappy.

Now I really need opinions as to what this is. I have pretty much new everything. Air filter, plugs, oil and tranny fluid, whatever. So what's the problem? Car is just having a bad day?

 
Rep Power: 287

what do the days have in common? rainny, u might be getting water in something. try to find the common factor that will help u alot. and does it hesitate like a miss fire, maybe run too rich like your o2 sensor is going bad.

 
Rep Power: 811

Good ideas. The good and bad days can actually be just an hour apart! Same conditions. Sometimes it gets a good mood and runs fast, other times it feels messed up. I had a feeling about it running too rich, becuse plugs were black after 18K miles.

 
Rep Power: 452

its a civic, mine is like that too, I just learn to live with it and hope someone rear ends the hell out of me soon.

 
Rep Power: 0

^^ same here.. just like that... hmmm

 
Rep Power: 0

Our engines are definitely temperamental ... prolly something to do with the ultra-sophisticated programing of our ECU's. Ergo, give the babe a brain and she's bound to have some bad hair days.

 
Rep Power: 424

Beat it up until it quits bitching. Seriously, just rag it.
My car does it too, I can tell within a minute of it starting it'll be pissy, I just warm it up and pound it a little. I don't know if its humidity related or what, maybe a little water settles in the gas or something but running it hard seems to flush it out.

 
Rep Power: 0

Yup, mine does the exact same thing. Some days, it's running like new, other days, it just feels very sluggish.

I'm pretty sure mine is temperature related, but the strange thing is that it runs much better on hot days, than on cold days. I always thought that cooler air gave better performance for the engine ...

 
Rep Power: 811

I was thinking it may be humidity as well. Cause then more water gets into the engine and bogs it down.

 
Rep Power: 0

that happens to my car if I don't warm it up.. so I always warm it up until the temp. gauge reach the right temp...

 
Rep Power: 285

My car is slow as HELL on hot days. And sometimes when i stop at a light it idles so low that it almost cuts off. At night it just feels so much more responsive.