Scary engine start

[angryBits]

Thursday evening while starting up my car to head home from work I experienced some very serious thrashing from my engine :(

Nothing weird prior to this and I didn't do anything rough with the car in the last few days, just some normal commuting.

So here's what happened:

I started the car (like you do) and immediately the whole car starts shaking violently in what seemed to be a regular pattern. This went on for about 3 seconds while I was in shock, before I could get my sense together and turn the car off, it managed to knock itself out.

My first thought was that there was some unburnt fuel in one of the cylinders and maybe it got into some weird timing.

So I waited a minute and tried again. Same exact result.

So then I open the hood and immediately feel that feeling I imagine a non-knowledgeable car person must feel when stranded along the side of the road looking at the engine with the hood up and absolutely no idea what to do next...

My gut was telling me it was one of the pistons either blown or not firing. First things first I unplugged the car battery and hope to reset the computer. Tried again and same result (I knew this was a long shot).

So next I tried pulling all the spark plugs and looked for some gunk that may cause a bad connection, but nothing funny. However when I pushed each of them firmly back into place and tried to start the car, it started right up - no problems except a persistent check engine light.

I drove home in the slow lane staying out of boost and trying to keep it below 2k rpm as much as possible.

After checking the DTCs with my HPTuners, I found a P0606 code, "ECM Failure". I cleared the code and took it for a drive and had no problems. After building up some trust I did some really hard (loud w/ spinning tires) starts and highway WOTs. Everything seemed fine with no more codes and my HPTuners didn't show anything weird during the drive.

My guess is that it was a loose spark plug wire, but why would that throw a P0606?

Could it actually be a faulty ECM and just coincidence that it resolved itself around the same time I messed with the spark plug wires?

[2013ZL1FUN]

I've seen a lot of posts lately with the loose spark plug wire theme. Maybe there is much vibration with this engine combo that causes this loosening of the wires? Also many bad ECM posts. Maybe you are lucky your ECM went bad under warranty?

[angryBits]

Originally Posted by 2013ZL1FUN

I've seen a lot of posts lately with the loose spark plug wire theme. Maybe there is much vibration with this engine combo that causes this loosening of the wires? Also many bad ECM posts. Maybe you are lucky your ECM went bad under warranty?

Except I cleared the DTC. If its going to go bad again, then hopefully it goes bad a week before my warranty runs out

[RJ111]

My car did the same thing a few weeks ago. My car also flashed reduced engine power. I let it set a few minutes, started it up and it was fine. But the check engine light was still on. It had two codes, P0606 and P0113. The dealer changed out the ECM, and the battery. They did say the ECM was bad. After a few hundred miles, everything is fine, so far.

[Redlineviper]

Sounds like limp mode to me. My buddies car would occasionally go into limp mode and had a loose injector plug that was sometimes cause it.

[Stephen12ZL1]

Some have reported their ECM needed replacing and the unit itself had a few loose pins

[Scott@Bjorn3D]

Originally Posted by 2013ZL1FUN

I've seen a lot of posts lately with the loose spark plug wire theme. Maybe there is much vibration with this engine combo that causes this loosening of the wires? Also many bad ECM posts. Maybe you are lucky your ECM went bad under warranty?

He has NO ECM WARRANTY, he has a tune and has voided the drivetrain warranty.

[Jeb114]

A lot of ECM's have gone bad, It's a common replace for Chevy. But you should not have cleared the code.

[Scott@Bjorn3D]

Originally Posted by Jeb114

A lot of ECM's have gone bad, It's a common replace for Chevy. But you should not have cleared the code.

But they check them for tunes, who is to say the tuner did not screw up the ECM. I do some IT work for the dealer in my town and GM voids the warranty if the ECM has been flashed with a non GM programming.

[Jeb114]

Well that's why I would not mess with a car under warranty!!!!! You pay for it in the price of the car why would you want to flush it away???

[Nor Cal ZL1]

Originally Posted by Scott@Bjorn3D

He has NO ECM WARRANTY, he has a tune and has voided the drivetrain warranty.

Maybe for you. Not for all. He has nothing to worry about if the ecu pins have bad soldering. If your dealer is so quick to throw you under the bus, you need to find one more reasonable...... they are out there.. now if he melted a piston, or blew out a diff thats a different story. If he lost a motor because an oil pump relief valve was stuck or something like that, which is not tune related, a good dealer will go bat, they might not win everytime but they will try.

[nighttowl]

I had a tuned ECU replaced under warranty on my SS.

[Redlineviper]

Originally Posted by nighttowl

I had a tuned ECU replaced under warranty on my SS.

A number of people have, it's just a dealer option. Loose pins would have nothing to do with a different tune as you don't touch the computer.

And why modify your car while it's still in warranty? Is that a real question?
Besides, the factory computer is not very expensive and you retain all of your warranty for anything that is not drivetrain related. Live life, enjoy your car and make it your own.

[Dutchman427]

Originally Posted by Jeb114

Well that's why I would not mess with a car under warranty!!!!! You pay for it in the price of the car why would you want to flush it away???

Because the car is kind of boring in stock form.