Please Help! Stalling, violent idle, no acceleration

[Chrisj4269]

Hello,
I am hoping someone can help me with my current issue as I have tried everything I can think of and am at my wits end with this car. It is a 2007 Aveo with right at 70,000 miles. A couple weeks ago it started missing randomly and then two days ago lost all power over about a 3 minute window and died on the interstate. I had it towed home where I ran codes and got P0300-multi misfire as well as every individual cylinder misfire code. I have replaced camshaft position sensor, plugs (copper core), wires, and intake boot (found large crack). It is still running absolutely terribly and occasionally dies trying to idle. I have checked fuel pressure (on, running, leak down) and all are in good range. I have verified no other vacuum leaks exist by using carb cleaner throughout. I can't think of what else it could be that's not throwing a code. I even removed the pre-cat O2 sensor thinking maybe cat was clogged and that would open it up enough to make a difference. That also had no effect. PLEASE HELP. Car is idling all over the place, won't pickup speed, and live code reader is saying that spark advance is going from -5 BTDC to +22. Gas pedal does essentially nothing unless you feather it very very slowly.

[Eg.h2o]

One word.
Coil.

[avguy]

What are the short/long term fuel trims and MAP sensor readings? Did you do a compression test?

[Sidnubs]

throttle sensor?

[Chrisj4269]

Just finished replacing the coil, no improvement.

[Eg.h2o]

Just finished replacing the coil, no improvement.

crap. Now I feel like an ass. In many instances, with similar issues on similar vehicles, and the codes provided by the OBD I’ve had good results making that call.

[Chrisj4269]

@eg.h20 no worries, it actually seems to be running better. Idle is considerably improved. Now the biggest problem is the occasional miss and the fact that holding throttle steady (even 50%), the rpms slowly drop back to idle. If I rev semi quick and let off quick, it stalls. I have fully cleaned throttle body as well.
Short fuel -0.8
Long fuel -11.7
Map -56kpa

[avguy]

Gently push the small vacuum tube connected to the MAP sensor while it's idling to see if it makes any difference in performance. A failing MAP sensor and/or cracked vacuum tube is fairly common on the first gen Aveos, and yours are suspect, based on the symptoms you've described. I normally always recommend diagnosing instead of just hanging on parts, but a vacuum pump is required in this case to test the MAP sensor. So if you don't have a pump, it's less expensive to just replace the MAP sensor and also that vacuum tube at the same time.

[Chrisj4269]

If the MAP sensor had an issue, would it throw a code? I'm not getting anything code wise now.

[avguy]

I had the MAP vacuum tube crack on both of our first gen Aveos, and also the sensor itself go bad on the '05 - never any map codes, just running rich like yours appears to be. I'm not saying that's it's definitely your vehicle's issue, just that there is a history related the MAP. And as I said previously, I never like throwing parts, but in this case diagnosing will cost $ to buy a pump and is a bit of a PITA. So that's why I suggest just buying the parts and hanging them on. And if it doesn't fix the problem, I'd cover this part hanging by calling it preventative maintenance