P0300 Code and no start

[TheDon]

My step dad called me and said the car would not start. It cranks but no fire. Awesome, so I leave my physics lab to go take care of it.

2004 Chevy Aveo 5 speed w/ 107k miles

I can't see anything visually wrong with it. Rented a scanner from autozone and I got codes

P0300
P0420

P0300 is a random cylinder misfire
P0420 is something with the catalyst( replaced 20k ago after it decided to go into melt down mode)

The intake hose from the air cleaner to throttle body has a nice gaping crack in it and a few vacuum lines I can visually see have cracked and some torn rubber connectors as well. I need to get this car back on the road asap.

thank you

[petrified.rabbit]

did you check for spark to each cylinder? i am thinking bad coil pack.. but it could be flooding, which would kill the cat in 20k miles as well.. did you have the repair done that killed the first cat? or just replace the cat?

[TheDon]

The dealership did the work for the cat about 30k ago. They replaced the cat, o2 sensors, and spark plugs.

I will check for spark tomorrow, the car was running just fine yesterday.

What is the best way to check for spark? I've never actually done that (I've owned diesel mercedes for a while)

[petrified.rabbit]

do you have a timing light?

[TheDon]

no, but I can probably rent one from autozone.

I have an iPhone so tomorrow when I go back to the car I will post my updates on the forum. I'm praying its only the coil pack.

[petrified.rabbit]

well if you get a timing light, pull the cover over the wires, hook it up to each wire individually and see if the light flashes.

If you get all 4 flashes, you have spark, when on cylinder 1, check it for time on the crank pulley timing mark..

if you are properly timed, (i am assuming it turns over freely with no noise) and have spark. Mist the coil pack and wires lightly with water, if you have a light show, something needs replaced (whatever is lighting up)..

If not enough light to cause a no start condition.. then i am pretty sure you need to check the o2 sensors.

[TheDon]

Ok, I will do that.

as well as pull the timing cover and inspect. I didn't hear any weird noises.


how does one remove the upper timing cover?

[petrified.rabbit]

you dnt need to pull the timing cover, just figure out where to point the light on the crank pulley. it is notched for tdc, and there will be a spot on the block it lines too. (easy to figure out if its in time).

[TheDon]

Ok(I do need to do the timing belt asap)

My step dad did say after the incident with the clogged cat the car never felt the same. Wasn't as quick off the line and he just drove slower. He never actually drove the car hard, nice smooth shifts, never bouncing off the limiter or running it to the redline.

[petrified.rabbit]

reading through all your posts again makes this situationally difficult. If the car didn't run like "new" after the cat repair 20-30k miles ago. And you are at 107k miles without doing the timing belt, or even 107k miles on a few original parts. The problem could stem from a few areas.

Start with what i already told you, but i would probably at this point verify no ad engine noises while cranking over, and check the timing belt. It might look ok, but just slipped, so verifying timing marks is more important.

it could be the primary o2, depending on what the previous check shows. Did he have both cats replaced? i think that year had two cats, others do. it would be helpful (and VERY quick) if you had a scan tool with real time data. But i know that is probably out of your reach.

i would also suggest "feeling" and "listening" to your injectors, to see if they all click the same way. This is worst case scenario, but A stuck injector could cause your current problems as well as the original cat failure. But you need to be experienced to diagnose an injector issue.