Fuel System Issues?

Hello there!

I have an Aveo 2005 four door, and have for a little over two years. It has about 125,000 miles and has a few issues, but overall is a great little car. I'd really like to keep it for several more years.

Recently, though, I've been having issues with it. When stopped at lights or stop signs, it has what I can best describe as a "hiccup" when I'm listening to the engine, and feeling the vibrations through the floorboard. Where it will seem like everything stops - except some whirring - for a split second.

It's also hesitating when accelerating, and the codes have been reading that the pistons are misfiring periodically. It doesn't seem to be the transmission, as it's shifting fine otherwise, and where it always has. We also checked the vacuum lines for any leaks, and there weren't any.

It's also been hesitating around turns and on occasion up hills.

We think it's the fuel system, but aren't sure. Has anyone encountered this issue or have any thoughts?

Thank you!

Any CELs?
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Yes it could be the fuel system, but on these vehicles it's much more likely to be spark-related. I'm assuming you read a P0300 code. Have you done any maintenance in the 2 years you've had it? One VERY common problem is the leaking valve cover gasket, which lets oil into the plug wells, and eventually rots out the wires. Best to get that gasket replaced before (or at the same time) the wires are replaced. Next are the plugs - very easy to pull them, check their condition, and replace if worn. If both of those items are ok now, then you need to actually determine if the problem is fuel or spark, and then continue down which ever path it is.
A couple of very important things which are not related to your current question. Has the plastic thermostat been replaced with the metal version? How about the timing belt and related parts - do you know when these were changed last?

CEL was on, but the codes have been cleared while it was being checked. We're waiting for them to come back up. I have a print out of the codes, and I believe there was a 0300 on them. All of them were related to fuel, oxygen, or spark plugs, except one for the transmission (which is likely just symptomatic). I'll talk to my dad and brother about checking the wires, plugs, and the gasket and seeing what's up with it. We were going to do that tonight, but didn't get around to it.

Good to know on an Aveo that it's not usually fuel system related.

The plastic thermostat housing (I assume that's what you mean) was replaced with an aluminum one in summer of 2012. I don't know when the timing belt and such were replaced, but I can bring that up.

Thank you for your help.

Okay, good news is that it seems to be the spark plugs. I checked them tonight when the car was laboring more due to moisture. We'll get that taken care of this weekend.

Thank, all!

on my 06 LT i had a misfiring issue pulled out the plug wires and fount 2 of the holes half way filled with oil so i replaced the valve cover gasket (added a bit of rtv to the outside edge just for a litte extra insurance) while i had i off i pulled the spark plugs and replaced them cleaned out the holes with carb cleaner and shop rags replaced the wires put it all back together and ran like a champ till the alternator went south :(but that is another story