Good luck my friend, I'm thinking it's just a sensor failure or loose wire.



I'll still trade the reliability of the Vette for my Lotus

 

This is either going to be a really easy problem to fix or really difficult.
The heater circuit failures on both cylinder banks is weird. It makes me think the problem is more than just a bad o2 sensor. A wiring harness rubbing against something could do it and be intermittent. The flashing check engine light means a catalytic converter damaging misfire, so for at least a short period of time it was running terrible. The o2 sensor circuit (not the heater circuit) if shorted against something would cause essentially a full rich condition for a short period of time, and could explain the flashing light.
In summary, based on the symptoms that have been observed, I would start by looking closely at the wring harnesses leading to the o2 sensors, and I would be expecting something dumb, like a clip not being fastened allowing the a harness to touch something hot, or rub on something sharp, to be the culprit. Particularly if the fuse for the o2 sensor heater circuits is blown, and it probably is.

 

Thanks for the tips, PT.

It only ran for about 2 minutes or less in that condition at no more than 30 mph and 2.5K rpm, and the engine was stone cold after just leaving home. Yes, it was misfiring badly. I pulled over immediately and shut down. After a 10 second wait, I restarted, it fired immediately with a normal idle, the flashing CEL changed to a solid one, and the engine was running normally. I carefully drove it 1/4 mi. back home since it was still cold, and parked it in the garage.

Fortunately, the tech who'll be working on it is legendary in this area as one of the best Corvette techs in the country w/ 40 years of experience on Corvettes and a wall full of awards from Chevrolet. I'm pretty confident if anyone can find it quickly he will. However, I will mention your wiring harness possibility, which is interesting and plausible.

 

Good luck Foosh. Hopefully it will be a minor issue.

 

I had the same thing when my car was only 200 miles. I shut down, restarted and it never happened again. Took it to dealer and they couldn't find anything and it has never happened again. That was over a year ago and now the car has 4200 miles on it without any issues.

 

Do you know for a fact your car displayed the same codes? Did your check engine light stay on after the misfire, shutdown and restart? Did the dealer just clear the codes, and it never recurred?

 

@ The OP.
Yeah running for just a few minutes is a non issue. You would have to drive it around for an extended amount of time before it would hurt anything. Probably at least one hundred miles. I'm not at all surprised to hear that once you shut the car down, and then restarted it, the problem disappeared. Shorted wiring almost always starts out as an intermittent condition. The act of stopping the engine and restarting it can easily be enough for shorted wiring to temporarily become functional again. This will be the biggest problem your going to face as this car is being repaired. It is entirely possible it could take many more hours of drive time before the car presents the symptoms again.
As far as the tech who is working on the car goes, you don't necessarily want the best corvette guy handing this. You want the best drivability and electrical guy handing this. One electrical problem is the same as another regardless if its a corvette or a truck, from the perspective of the tech. Sometimes the best "corvette guy" is the heavy repair person changing engines and transmissions and so on, which is a different discipline altogether.
Last... Feel free to actually print any of my posts and present them to the service advisor, or service manager, or the service tech, or anyone else who gets in the way, at anytime, without further notice to me. In fact if these people cant actually successfully fix this car, then I want to know about it.

 

Sorry to hear that.You must have been,shocked to say the least.
Good call on the Hauler and
MR.GOODWRENCH
Just a minor bump in the Road.You'll have that Grin Again,right Quick

 

I would agree that you should not drive the car as at this point you don't know what the problem is.
I know you have an aviation background so here is a bit of an analogy.....cruising along in the flight levels you get a " FIRE WARNING LIGHT ILLUMINATED # 2 engine" . A quick look around indicates the engine is still putting out power, no vibrations, all parameters look normal.Probably an indication problem but we don't play that game . We pull the fire handle, if the light goes out fine, otherwise put a bottle to it. Take the safe route

Back to your baby, you have GM roadside assistance, call them remind them you need a flatbed and a driver that knows how to load up the vette.......all covered and GM now somewhat involved if something goes wrong during transport.
Once safely at the dealership let the tech do the warranty work to make it right, probably a sensor/computer...........no big deal
Apologies for the " engine fire analysis...couldn't help myself, LOL.

Good luck with the repairs and please post results.

Doug.

 

Hope this is nothing more than a minor glitch foosh. Maybe just a new ECM.
Keep us informed.

 

Bingo, exactly my approach and thanks.

And like all well-prepared professional pilots, I own all the equipment necessary for the flatbed driver to not screw things up, and will supervise the operation. I was pleasantly surprised when I talked to Chevy Roadside Assistance that the rep said all C7s get flatbeds only.

 

Another vote on the O2 sensor. Certainly not what you want to happen with a new car. GL getting it remedied quickly.

 

Yeah, but why codes for both O2 sensor banks? I could see one failing but both at the same time. That's a concern. A simple O2 sensor failure would be easy, but codes for both raise other questions like the wiring harness issue PT raised above. It could also be an ECM issue, but that would also be easy.

 

 

To me the real mystery is why did it run badly.
You can cut the wiring in half and totally disable the heater circuits for one or both o2 sensors and it wont cause the car to run rough. It will just set the codes indicating an error for the heater circuit or circuits. So the question becomes, what could cause both the heater circuits to fail and cause the car to run rough at the same time. Knowing the car is basically brand new, its not really all that probable a component has failed, after all its basically new. Its much more likely that something related to assembly has occurred, after all it was just assembled. So what kinds of things related to assembly could cause all of the above. Well one thing could be if a wiring harness wasn't clipped into a retainer properly and was touching the hot exhaust, or rubbing on something sharp, causing both the heater circuits and the sensory circuits to malfunction.
Anyway, could I be wrong ? Of course I could, but whatever the failure is, it will be explainable in a way that makes sense with the evidence at hand, and if it doesn't, then whoever is doing the explaining is probably wrong.

 

fuse for a sensor....first time I've heard of this. I think there's 4 O2 sensors so that would mean a separate fuse for each one.

 

Not necessarily, there could easily be one fuse for all four, or two fuses one for each pair of sensors. In the unlikely event someone posts a wiring schematic then we can know for sure, but I don't actually have the schematic.

 

Wow, Clay!

So sorry to hear of this, but the good news is it will all be covered, and your dealer is a known good one (I assume the car is now in Bowie?).

 

Well I guess the C6 has a O2 heater fuse which feed all 4, it's marked O2 SEN and it's a 15 amp.

 

Ok good.
Yeah the c7 is likely the same.
So what this means is one o2 sensor harness shorted or melted could blow the fuse and set codes for both sides, and perhaps the post converter sensors as well provided someone drove the car around long enough, although that didn't happen in this case.