Idles fine, but stalls/dies at 2000+ rpm - long post, please help

I've been searching google and this forum for a couple of days now and done some work to my car, but to no avail. I am not particularly experienced at any kind of automotive work, but I do consider myself "mechanically inclined" and tend to be a fairly quick study (and my experience has steadily been increasing, but consists mostly of coolant system and brake work as well as oil changes).

Here is my situation:
I have a 2006 Aveo with about 95,000 miles on it. It had been running well up until Saturday morning (today is Monday - timestamp) when, shortly after exiting the highway, it began to buck and lose power. My CEL came on, I pulled over, and checked for cracked vacuum hoses. Finding none, I went to a nearby Autozone to check my CEL.

I got a p0300, p0301, and p0304 - misfires for random, cyl 1, and cyl 4 (listing possible causes of ignition system, vacuum leak, injector fault, high or low fuel pressure). Being 1 & 4, I went ahead and bought a new coil and headed home. At this point the car bucked a little every time the RPM dropped for gear change (auto trans, btw).
About 2 miles from my house (after driving about 15 miles to the Autozone and 13 miles back), I lost all power and puttered at about 2 mph and then the engine died. I pushed it up into a parking lot where I connected the new coil, but because I didn't have any sockets, I just unplugged the original coil and plugged in the new one without mounting it (not sure if it required grounding or not). I was able to start up, but when I tried to accelerate, I had no power and if I let off the pedal, my car would buck and die. I puttered over to another Autozone just a few hundred yards away and checked my spark plugs, which were pretty well soaked in oil. I hadn't changed the plugs but once and many years ago, so I figured there could be a minor leak in the valve cover, but probably only minor - something to deal with later)

I retrieved my sockets and tools and went ahead and replaced the plugs, plug wires, and properly mounted the coil (noting that I did get some oil into the chamber, but thinking it would burn off easily enough). Still would idle fine, but have very little power, and would die upon relieving the gas pedal.

I could hear a loud hissing and found that it was coming from the EGR valve, but not at the mated surface, but between the solenoid and the body, like around the standoffs. I put electrical tape around it there and I could no longer hear the hiss, but the problem still occurred. Thinking my tape job just sucked, I went ahead and bought a new EGR valve and as soon as I turned on the engine, I could again hear the hissing from the same location, and the problem still persisted, so I took it back off and they let me return it for full refund.

At this point, I had left my car there overnight and was consulting with the Autozone guys and one noted that I had a lot of white smoke coming from my exhaust when I was driving and showing him the symptoms. I mentioned that I probably had a little oil in the chamber and we checked the plugs, which were once again soaked.

I towed my car back to my house so I didn't have to keep operating in the AZ parking lot and changed the valve cover gasket. Now, I did not drain the oil in the pan because I just changed it 3 weeks ago, but the oil I could see and the parts it was covering looked fine, but there was a small amount of frothy yellowish oil in one section on top of the inside of the valve cover. I didn't think much of it then and considered it was probably just condensation, but please let me know if it is more serious and/or possibly related.

I also thoroughly cleaned out the combustion chambers of any oil, re-cleaned the spark plugs (brand new, but oiled up pretty good; cleaned with TB cleaner)
I used throttle body cleaner on all the hoses, the one plug, and around what I take to be sealing surfaces on the air intake manifold, seeking a vacuum leak, but could not find one. I could not get to the back side of it however, so a leaking gasket has not been ruled out, in my opinion.

In park, I removed the intake hose (which I found had been cracked for some time before taping it up last time I changed the air filter, approx. 3-4 months ago) and had someone slowly rev up to about 2000-2500 rpm and watched the throttle blade. It seemed to suck strongly in idle, gradually open with throttle, but when the engine kicked and died, the blade opened up wide. I could not tell which happened first and neither do I know what is correct function, but it seems to me that it was somehow looking for MORE air.

The last symptom that seems to have developed and is quite possibly unrelated to anything other than the violent shuddering of my engine is a metallic rattle in one of the bodies in line on my exhaust as well as what I would consider an excessive amount of condensation/water coming from the tail pipe, sometimes accompanied by very fine black deposits. No I haven't driven through any water lately and it's not a constant stream, but occasionally it will spurt and then drip. I haven't seen it with my own eyes, but after holding the revs at about 2000, I had wet concrete with black spots (very "carbony"). The rattle seems to be in the middle body in the pipe assembly, (possibly a resonator?); the one before the muffler.

This afternoon/evening, I will have access to a fuel pressure gauge and a compression test gauge. Can anyone tell me what the fuel pressure should be at the rail?
If pressure is good, then I'd like to check the fuel injectors. Is there any "easy" way to do this? I was thinking I'd unhook the plugs to them one by one to see if there is any change. I would think that no change means bad injector.
I also will check the timing belt and make sure the marks are where they should be.
I will also check to see that each spark plug is actually firing and check fuses.
On an '06, is the fuel filter integrated in the pump? And is the pump actually in the fuel tank? I can see two items connected to the fuel tank, both behind it. One is a rectangular box shaped item, and the other a canister that I found to be an EVAP valve. Is the rectangular part the pump, or something else?

I know it's been a long post and I appreciate y'all looking it over for me. It was my intention to be as thorough and specific as I could. Any suggestions or knowledge you can give me will be much appreciated!
Thank you
Adam

I'm sorry to hear about your problems. Your pump is in your fuel tank, the filter hooks up underneath it. Have you tried to run it with the new plugs? And you didn't mention if its overheating. Not sure how much help I can be, but I know you gotta replace the valve cover gasket, those plugs sounded fouled. Do a compression test if you can

Temp has been and remains normal. I have replaced the valve cover gasket, but only after the brand new plugs ran in oily condition for a short time. Would they be ruined that quickly? Visual inspection had them looking okay, but the problem still persists as it did before. I will try a compression test this evening, hopefully.

So I should be able to change out the fuel filter?

Fuel pressure at rail said 55-60 psi.
Sounds high to me, but what would high pressure indicate?

Checked each spark plug by pulling the out, grounding, and turning on ignition- all firing

Checked compression. Each reached about 190-200, but 1 and 4 jumped up there after a few cycles, whereas 2 and 3 got there a little quicker. I've never done a comp. test before, so I'm not certain what's normal. Also, should I rev the engine while checking compression?

The symptoms seem to be getting worse. Now it is having a harder time starting, it doesn't handle being revved at all, and the intake manifold is vibrating so much that it sounds like a helicopter (it had not been doing so before). The rattle in my exhaust has also intensified and even moved. It is now further along near the muffler just before the coupling flange. I am considering removing that entire section of pipe (looks like two flanges and at least two hangers; I haven't gotten a good look). If there is a partial blockage in the tail pipe, would that cause my symptoms? Something breaking loose inside could explain the rapid onset of this problem (as opposed to symptoms slowly revealing themselves and getting worse over time, as it may have if something was wearing out or clogging up)

Just FYI if you see white smoke after start-up that stays low to the ground that usually points to a blown had gasket or worse a cracked or warped head . Pull dipstick and clean it. Crank it up and let it run and watch the white smoke then turn it off and pull the dipstick and check it for a yellowish watery oil. By the way the problems you describe all lean in that direction.
There are many quick fix's out there but if I were you and it is a head gasket I would use steel seal. YouTube it for yourself and you decide. I replaced the head gasket on my daughters 2005 aveo when the thermostat housing cracked and she ran it HOT.. and she has been having the symptoms you describe, radiator bad, she ran it hot Again. So I am going to try it myself this time. Hope this helps:-)

its very possible that in your attempt to fix the other problems and allow oil into the cylinder you fouled your o2 sensor.

i would check and clean that before going further. (any chance you have another code at this point?)

The o2 sensors are the ones before and after the catlyric converter, correct? I will pull them tomorrow.

Wewaman, since I cleaned the ignition chambers, I have not gotten any more heavy smoke and my dipstick oil has been clean. Btw, my thermostats housing blew up on me a few years ago, too. Fortunately I was in my neighborhood and was able to push it home. As I recall it was a particularly cheap part, destined to fail from the beginning.

Quote:

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Originally Posted by ATWork8803

Checked each spark plug by pulling the out, grounding, and turning on ignition- all firing

Checked compression. Each reached about 190-200, but 1 and 4 jumped up there after a few cycles, whereas 2 and 3 got there a little quicker. I've never done a comp. test before, so I'm not certain what's normal. Also, should I rev the engine while checking compression?

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It sounds like you're doing the compression test with the engine running - is that correct?

And as a matter of fact, I have gotten some more codes, but I don't think they're helpful:
P1616 - I think this indicates that I ran with something unplugged, which was most likely the egr valve
P2106 and P2110 - This indicates a "safe mode" where basically the gas pedal is disabled - I got this to occur twice by messing with vacuum hoses in an attempt to force certain conditions
P0107 - Manifold Absolute Pressure sensor low input - also likely caused by messing with vacuum hoses.

All of these codes disappeared without being cleared after a couple of startups

Quote:

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Originally Posted by avguy

It sounds like you're doing the compression test with the engine running - is that correct?

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That is correct. How else do you get compression?

Edit: I just looked it up. Gotta disconnect the coil so it only cranks. Hmm. I was listening to the guy who let me borrow his compression gauge. So does that makes my results invalid? Or worse, could I have caused any damage??

Edit 2: Did a little more looking and it sounds like I just did a "running compression test," though much less thoroughly than a pro. One thing I read is that the running compression should actually be lower than static and at 200 psi, I'm running pretty high already. One source suggests clogged cat converter, which, along with my rattling exhaust could be something worth checking.

No damage done. Pull the fuel relay, remove all of the plugs, and have a helper crank (WOT, just a few times for each cylinder), while you watch the readings. Carefully note if some are taking longer to move up, and what the final readings are. Then you can repeat the test, adding a few squirts of motor oil into the cylinder to see what (if anything) changes. Sometimes the compression test doesn't tell the whole story, and a leak down test is also needed to complete the picture.

Thanks, avguy.
WOT, as in with the pedal to the floor, or manually opening the throttle plate?

Quote:

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Originally Posted by ATWork8803

.... One source suggests clogged cat converter, which, along with my rattling exhaust could be something worth checking.

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Many things could be the cause of your problem. But the fact that it went from running well to running very bad with misfires, in a matter of seconds tends to eliminate lots of things. Unless the cat broke apart inside, I can't imagine it causing such a sudden and significant change in the engine. A sensor failing, or a mechanical failure seems like the only likely suspects in your case.
I think you should do the standard compression test, mainly because you want to see how much of a difference there is in the cylinders, both final compression and how many cycles it takes to get there.

Quote:

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Originally Posted by avguy

Unless the cat broke apart inside, I can't imagine it causing such a sudden and significant change in the engine.

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That was a big "unless," my friend! That's exactly what it was. Pulled my pipes and found a bunch of chunks. Pulled my cat and found it half empty and with the remaining honeycomb partially melted and broken. I fired it up with nothing but the exhaust manifold and it revved up to 4k with just a tap of the pedal and no problem to be seen!

Now the plan is to knock out what's in there so I can drive it while my new cat is on order

I will post up pics shortly.

Thank you for posting that information - good chance it will help others down the road!
Are you buying just the cat, or some of the other pipes behind it as well? Are the flange bolts rusted? No big deal if you weld and have that equipment. I recently had to replace the muffler on my '05, due to the mid pipe connector rotting out. I don't have welding skills, so getting those bolts cut out (without damaging the flange) was a RPITA.

All the pipes, flanges and bolts look to be in good enough shape. All of the nuts (pipes and cat) were pretty well stuck on and the threads on one of the cat mounting bolts was damaged, but I managed to run a chaser over it. It *should* work out okay. Anyway, I've got a new cat coming so it won't be a problem or risk for very long.

By the way, I found a new cat for $165 at rockauto.com (let me know if such posts are against the rules on this forum) (RockAuto Parts Catalog)

At Autozone, the least expensive is $360

Must be nice to work on vehicles that don't spend their lives in the rust belt :rolleyes:
No problem posting sources and brands for parts - it's one of the pluses of these auto forums to get that information out to other DIYers. I've always had good luck with Rockauto - they deliver the right stuff in a timely manner. Happy motoring once the new cat is on :thumbup:

Thanks avguy. Yeah, Texas has got some bad humidity, but fortunately we don't get much (any...) snow and don't have to worry about salted roads!

I put my hollowed out cat back on last night. I took my muffler off before I tried to run it, though and I'm glad I did! It was full of chunks, dust, and water. I was able to dump out most by rocking it back and forth and beating on it with a piece of wood. I'm not sure exactly what's going on inside of that muffler, but I would dump it one way and get some chunks and dust, dump the other way and it would vomit water, and go back and forth like that and get something new every time (until I had notably less water inside and was no longer seeing any dust).
I tried it first without my muffler and it was loud, but revved beautifully.
I put back on the muffler and it sounded and felt so weak. It even stuttered a bit when I'd rev it. So finally I drove it and running around the neighborhood, it still felt like it wanted to cough just a bit, and many times it wouldn't want to change gears unless I quickly let off the gas - I expect that is a good symptom to watch out for when it comes to clogged exhaust: I got up to 4-4.5k rpm going along in 2nd or 3rd and it didn't want to shift until I released gas pedal (automatic transmission)

Anyway, once I got out onto a wider street, I got up to and held 70-80 mph and it must have blown out the remaining debris or at least shoved it to an innocuous location inside my muffler because it has driven like a champ since then - startup, low gear, high gear, no problem changing gears, etc.
The only thing I really notice is that the hollow cat rings like a bell at 2500 rpm and up. Not really loud and a low tone (kinda pretty, really :D), but noticeable with the radio off.

I know I've posted an awful lot on this, but my mentality was that I would have killed to have come across a post like this one while I was researching my seemingly hopeless problem. Forums like this are a Godsend for people like me and any other thrifty DIYers without much automotive training!