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OK Internet Mechanics, get your thinking cap on

13K views 22 replies 8 participants last post by  Careful 
#1 ·
2011 2.4 Auto
in January, daughter was driving to gym at dark-thirty in the morning, we'll call it +15deg F outside.
Had warmed it up before she left, drive about five miles, pulled up to a stoplight to turn left, boom. Engine quit.
I get there 20 minutes later, car starts, and immediately dies. Over & over & over.
I tow it to my shop, has 55psi fuel pressure, has spark, and is still doing the start/die thing.
Pull codes, it has a P0010 Intake cam actuator stored & not much else. I think it had a low voltage code in it, most likely from trying to crank it.

Charge the battery, start diagnosing. All I can find wrong with it is not a damn thing, until I try to pulse the injectors. When I get to #3, and crank the engine to build back fuel pressure, the sToOpiD thing starts, runs, idles, & purrs like a kitten.

So I put it all back together and walk away from it for a while. Come back later, start-die, start-die, start-die..

And it's throwing NO codes. it's simply flat slap plumb shutting down.

So out of desparation, I run to the local House of Recycled Auto Parts and grab a PCM out of a similar car.
Unhook the factory PCM, clip in the boneyard unit, NOW it won't fire at all. Just cranks.

OK, I figure, going to have to go to Chevy for a factory PCM & a flash..

Hook the OE PCM back up, boom. Car starts, runs, idles, purrs. And has for the last three months.

Until today. She's leaving school (college) coming home for the day, get to the end of the college driveway, ready to turn onto the main road, AAAaannnndd it quits again. Start-die, start-die, start-die.

I ante up $100 to have it towed from a county over, get it to the shop & off the wrecker, and it start-die, start-die, start-die.
Hook the scammer back up to it, the P0010 intake cam code is back, and decide to start by pulling the PCM.

Unhooked the PCM, stood there for a minute, hooked it back up, reached in, hit the key.. Vroom. purr, purr, purr, purr..

Dafuq is going on with this hoopty? Between the senior three of us, we have 100 years combined experience (30+ years each), and we're baffled.

WHAT could be goofing with a PCM like this?
 
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#2 ·
I'd start by replacing the PCM altogether with a brand new part since that seems to be the crux of the problem.

Otherwise, replace the VVT cams to eliminate the P0010 code, then make sure it's going to run long enough to trade it in. I wouldn't feel comfortable with a car that intermittently strands your daughter with no warning.
 
#3 ·
My daughter added this evening that both times it's happened, she was turning left.

Has anyone ever seen a problem with module feedback into the CAN buss like the trucks do?
 
#4 ·
The dying while turning left really caught my attention. There had been a similar known issue with the MN12 series that usually meant a battery cable or some other wire was causing a short. Turns out your kind of car apparently has a power steering switch that can cause the same exact problem. Another thing I would check would be the fuel pump as if it is being starved like oil pumps can be during turns. Once again shorts with those same parts could cause the same issue.
 
#5 ·
Check with the dealership to see if there was ever a recall or TSB about the alternator wire running too close to the coil pack and the coil pack needing a proper ground. When turning, EPS draws a lot of current and at times it can induce current into the primary coil circuit and disrupt the spark.

Another issue about which you can find a large thread is called "fretting corrosion" (use Search feature to find it). Since all you really did 3 months or so ago was unplug and plug back in the PCM, that suggests to me that it could be as simple as dirty terminals. Cheaper to unplug and reinsert the plug several times than to start throwing parts at it.
 
#7 ·
Not sure about the coil pack thing because as I mentioned, this is a 2.4 Ecotech, which is a COP ignition.. on the old 2.4 "flat cover" I could see that in a heartbeat.

The fretting corrosion could be a possibility.. although the bulkhead connectors at the PCM are clean as a whistle inside, it doesn't mean that heat/vibration hasn't loosened the "crimp" so to speak on the females in the connector. Which would explain the disconnect-reconnect temporarily solving the problem..

I'm off today, but am gonna head in to the shop after I get my taxes done..

I'll let you guys know tonight what I find.

That's how these forums are supposed to work!
 
#8 ·
The corrosion thing is a real problem. The TCM and entire underhood fuse box were replaced on my car right before I bought it for corrosion. And the BCM causes issues about every 9 months where the terminals get enough corrosion to cause the brake lights to stay on and cruise won't work. (There's a recall associated with this). So I have to unplug the BCM connections and plug them back in several times and it fixes the problem for 8-9 months at a time. I can never really see any corrosion on any of the connectors. But it must be there due to the issues it causes. And the BCM is inside the car, in a very well protected area that gets no outside moisture other than humidity. So I wouldn't take it for granted that the terminals are as clean as you think they are. Maybe a little dielectric grease on all the pins would help. It sure wouldn't hurt. I need to do this as well.
 
#9 ·
That's what I did today, I pulled the PCM connectors back apart, sprayed some contact cleaner in them and smeared some dielectric grease in them and buttoned it up.

I drove it home from my shop with it not skipping a beat.
I'll drive it for a couple days and see what happens. The local mega-dealer didn't return my call asking about a re-flash for the PCM or a TSB.

The closest one I can find in Prodemand is the one I mentioned in my reply above, but that one applies to the trucks. FYI, ANY module in the LAN system on a truck can cause a no-start condition.

Anyone have access to Identifix? I don't anymore.
 
#11 ·
#12 · (Edited)
I use a spray called Deoxit on all my CAN bus connections now whenever they are apart.
Full power down and "reboot" of PCM should always be attempted along with connector cleaning, grounds, etc. before PCM swap outs.
Today's CAN systems are very sensitive to connections. They are here to stay and we've got to relearn that not only power moves through connections but also data and poor connections means corrupted data and no, poor or erratic operation.
Fretting corrosion is a GM problem and that's always the first thing I address in my fleet when having to do a repair.
 
#13 ·
Changed the solenoids out this morning. Thanks again, Frank.

Still cant get the local Chebby dealer to call me back on the why question. I kinda see his point. He's paid to know, and you need to pay for what he knows. I'm in the same boat with what I do.

When I pulled the intake solenoid out, the oil passages were absolutely caked with some frankly pretty scary looking chunks of aluminum. My alignment guy found the same thing on his HHR, and his dealer gave him a new engine. But it took some work on his part. Calls to GM, the CustServ Rep, dealer principal, etc before they would consider it.

So, my question is; Do you guys think it would be worth it to me to follow the same path, or should I just cut and run, and trade it on the used Silverado 2500 I found?
 
#14 ·
Should have took cp-the-nerd's advice and sold that pile..

Timing chain broke on it yesterday morning.. all balled up in a little wad in the bottom of the timing cover..

Called GM this morning, "..well, the engine warranties have expired, but there are two open recalls.."
 
#15 ·
Wow, thats a pretty rare failure. Never really hear of a timing CHAIN breaking. My first engine made it 194k miles and the chain didn't break but something else did. You just never hear of timing chain failures, ever!

Good news though is that you can find used motors for not a lot of money. And it's very straight forward to swap out the motor. I did it, and didn't need to pull the tranny with it or anything. Just unhook everything, unbolt it, bolt in the new one and away you go. I was able to get a used motor with 42k miles for $600 from a local salvage yard. I've since put about 50k on that motor, and it's been 100% perfect.
 
#16 · (Edited)
Here's the current situation..

When the cylinder head was removed, we discovered lunched exhaust vales in the #3 cylinder. The original plan was to have the local machine shop clean, check and deck the head, replace any needed valves, replace the chain and go on with life..

When the timing cover was removed for inspection, we found broken chain guides, broken bolts and other bolts that had been ripped from their holes.
A simple job just got complicated. Seeing as how a head gasket set is $200 bucks, head bolts $150, the timing chain & related parts in excess of $300, I called the local salvage yard. They sold me a used engine with similar miles on it (85,000) for $450.

We're going that way.

Due to the level and type of damage, and the metal flecks I found when I replaced the VVT solenoids, I'm suspect that the intake cam seized to the cylinder head.

The final loan payment was made on the car in February.

Initially, our plan was to refurbish my Superduty, and have her continue to drive the Malibu as a daily driver.
This has changed out plans.
The Malibu and Superduty are both shortlisted.
We're looking for a 3/4 ton gasser to replace both vehicles. And I'm off to join the Autoguide Silverado Forum (I already belong to a couple Ford Truck forums in the Autoguide family).
 
#17 · (Edited)
Pictures of the carnage (sorry about the quality... I was holding my borescope in my hand saving the images..


damage to oil pump, more oil pump damage, the broken chain, kiss marks on the piston where the valves hit, abrasion of the balance chain guide bolts by the timing chain
 

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#18 · (Edited)
more carnage

kiss marks on the #3 exh valves where they hit the piston, bent valve propped open, chain giude worn through to bolt, then worn on bolt, debris in the VVT solenoid holes (which I had cleaned two days earlier)
 

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#20 ·
Geeze thats crazy! But to be honest, $450 for a motor, and just keep driving it. Why get rid of it, now that you'll have a fresh motor? Like I mentioned, I've been driving the hell out of mine. Other than the motor, the rest of the car has 245k on it. No major issues to speak of other than two things that are covered by recalls for most cars with less miles (electric power steering, and BCM corrosion causing brake light/cruise issues). I'd keep it now that you've put the money into it.

But good call ditching the super duty. :D
 
#21 ·
But good call ditching the super duty. :D
It's a Ledge-un-dairy 7.3
I'll have no trouble brooming it.
You know why 7.3 owners are such grouches? Because we got all that displacement and no power.
 
#22 ·
its funny you mention the 7.3. I flip a couple trucks a year just to make some extra money on the side. The 7.3 super duty's are by far the easiest to sell. Last one I had, sold it for $10k and it sold in 3 days. They're pretty easy to work on, and everyone loves them. I prefer a dmax obviously, but for a flipper they're the best.
 
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