2007 Aveo5: Cylinder 2 Misfire

[HamTracker]

I've been dealing with a cylinder 2 misfire for the better part of 2 months now and was hoping to get some advice.

When the code came up I only had 40k km on the engine had recently replaced the spark plugs last spring. I diagnosed oil in the spark plug tubes and fixed an o2 sensor code that also came up. After a quick gasket change I was good to go until this month: engine running rough and misfire in cylinder 2.

I take the car into a mechanic he clears the code new spark plugs (no they are new) suggests swapping out the map sensor (sure why not). The day after I'm getting the CEL again. I will have to decode when I get home from work, but I'm almost certain its still the cylinder 2 misfire.

My car seems to be running alright when its warmed up, but there is a noticeable delay in power. When the engine is cold it runs a little rough, but is a bit better after the map sensor was replaced. Any suggestions anyone? I'd like to get this situation fixed before a road trip this Saturday.

[avguy]

Have the plug wires been changed?

[jonelledge]

mine just gave me a multiple cylinder misfire, but seamed to loose quite a bit of power, while it was making a clanking noise. decided to find the noise. after 30 min of tearing the car down to expose the timing belt, turns out that it jumped time 1 tooth causing it to loose power. but the automatic tentioner broke (from what i hear it is fairly common) causing some slack, but the belt was replaced 20,000 miles before. but among other problems the mechanic that my mother-in-law (her car at the time) she took it to decided to some how to strip the threads on 2 of the bolts that holds the tentioner on, (3 holds it on) and the other 2 were loose causung it to move. and i guess break? anyways i replaced the belt and tentioner, making sure it was back in time right, threw the car back together in about 30 min or so and started up, ran just like it did before all that happen. one of the bolts that backed out was vibrating against the belt(slowly shredding it) while making all kinds of clanking noise when it was accelerating. but if you tentioner is broke, it might not be making noise. just something to check, if it is what it is it could save you a motor replacement. hope this helps you. ( im changing the timing belt my self from now on)

[jonelledge]

also we would clear the code and it would stay off a bit, then would be back on in several days.

[avguy]

mine just gave me a multiple cylinder misfire, but seamed to loose quite a bit of power, while it was making a clanking noise. decided to find the noise. after 30 min of tearing the car down to expose the timing belt, turns out that it jumped time 1 tooth causing it to loose power. but the automatic tentioner broke (from what i hear it is fairly common) causing some slack, but the belt was replaced 20,000 miles before. but among other problems the mechanic that my mother-in-law (her car at the time) she took it to decided to some how to strip the threads on 2 of the bolts that holds the tentioner on, (3 holds it on) and the other 2 were loose causung it to move. and i guess break? anyways i replaced the belt and tentioner, making sure it was back in time right, threw the car back together in about 30 min or so and started up, ran just like it did before all that happen. one of the bolts that backed out was vibrating against the belt(slowly shredding it) while making all kinds of clanking noise when it was accelerating. but if you tentioner is broke, it might not be making noise. just something to check, if it is what it is it could save you a motor replacement. hope this helps you. ( im changing the timing belt my self from now on)

Got me scratching my head there jonelledge. If 2 out of the 3 tensioner bolts were stripped (spinning), how the heck did it manage to go 20K miles with only 1 bolt torqued down solid? The parts outfits who ship the timing belt kits include a warning about getting the tensioning procedure exactly right, so it's hard to imagine how it could even run at all with a tensioner moving around. And how in the world does a professional mechanic strip TWO bolts? Stripping just one would make me want to wet my pants, so I can't imagine anyone making this mistake twice. Maybe I'm just not understanding what you're saying. How did you fix the stripped bolts - cut new threads for the next larger bolt, helicoils, or some other way?

[jonelledge]

im not sure the belt nearly fell off when we removed the cover it was that loose. and yeah it says to go all the way tight, the let the tention of slowly untill it reaches the center mark. (not sure they did that). live in a town with just under 2,000 people and youll understand """""professional mechanic"""". im a small engine mechanic, utv atv golf carts go carts weedeaters chain saws dirt bikes and mowers, so im aware of how things work, i could maybe understand 1 bolt, MAYBE! but 2!?!?!?! NO!! but anyways i drilled the 2 holes on the tentioner bigger to fit a bigger bolt, and i tapped the block to take the bigger bolt and the A LOT of LOCK TIGHT!!!! ive got just a little over 6k on it since i have done that, so its getting about time for me to check and make sure everything is nice and tight.

guess im just lucky that the belt didsnt come off, one of the bolts was rubbing the belt, slowly shredding the belt, and it was so bad that litterly half of the bolt head was gone!
dont trust anyone but yourself, its sad that thats what the world has gone to.

[avguy]

Well, nice job getting it fixed before the engine was trashed! A mechanic who strips bolts like that and doesn't fix them should get into a different, non-mechanical line of work.

[highvoltj]

So....my neighbors daughter is the proud owner of a 2006 Chevy Aveo and it started randomly misfiring and idled and ran poorly.
After plugging my scanner into it, codes for misfiring and o2 sensor issue's, I did the obvious and cleaned connection's, airflow sensor and cleaned throttle body, which was caked with oil deposit's...still same codes and more... The o2 sensor's were pretty bad so I changed both as the car would not pass smog due to ck eng. light illumination. Perplexed, I started reading possible issue's on these forum's and found a myriad of possible problems including notorious bad intake/exhaust valve's, worn timing belt, crank sensor etc.
I ended up visually testing the coil, and found the #2 coil was not firing at the plug, and after changing the $79.00 coil pack everything went away, no ck eng. lt, and car runs like a champion! Next time I will diagnose coil pack first as this seem's to be a common breakdown issue!