Corvette scared me today - loose plug wire
07-06-2018, 04:36 PM
#1
Racer
Thread Starter
Corvette scared me today - loose plug wire
So my 2018 Grand Sport scared the crap out of me today. I was driving home from physical therapy when the car started to sputter when I would hit the gas. I made it home and when I did I got an error message in the DIC about Stabilitrak and service rear axle. After some heavy forum reading, and a little bit of panic, I came across a thread mentioning to check the spark plug wires. So I opened the hood to check and lo and behold the wire for I believe #5 cylinder was dangling from under the cover. I plugged it back in as best I could (hopefully I got it back in tight) and restarted the engine and it sounds good again with no error conditions. Anyone know if this is a common and/or recurring problem and if I should get anything checked out to make sure it didn’t hurt the engine (since it ran on 7 cylinders basically coming home)?
07-06-2018, 04:44 PM
#2
Being that we run on 4 cylinders at times due to AFM you should be fine. (Not a huge fan of that) By chance did you get a any notifications thru Onstar or myChevrolet app?
Last edited by SoFloVette; 07-06-2018 at 04:44 PM.
07-06-2018, 04:58 PM
#3
Racer
Thread Starter
I usually have the AFM disabler in so I am always in 8 cylinder mode (thank you Range device 
). I didn’t get any notifications about it via OnStar but my trial with them is over (just have the free basic plan). I would have expected to get a CEL but didn’t get that either. Just the message about Stabilitrak and service rear axle. Thank goodness for the forum members that mentioned checking the wires first. Was a huge load off my mind when I saw the loose wire. I’m just hoping they don’t continuously loosen up.
). I didn’t get any notifications about it via OnStar but my trial with them is over (just have the free basic plan). I would have expected to get a CEL but didn’t get that either. Just the message about Stabilitrak and service rear axle. Thank goodness for the forum members that mentioned checking the wires first. Was a huge load off my mind when I saw the loose wire. I’m just hoping they don’t continuously loosen up.
07-07-2018, 12:15 AM
#5
Burning Brakes
Consider yourself very fortunate.
I ran into the same problem. Heavy misfire especially when cold, CEL, then the service stabilitrack warning followed by the service rear axle. Once warmed up it seems to run OK. but with intermittent stumble. P0300, random misfire mostly cyl 2 & 8 ,dealer checked plugs and wires and found nothing wrong.They performed fuel injector service and replaced one fuel injector. Problem is better, but still there. They are thinking carbon buildup, possibly a bad tank of gas (38k miles) They have contacted GM engineering for guidance. 2 weeks and counting!
I ran into the same problem. Heavy misfire especially when cold, CEL, then the service stabilitrack warning followed by the service rear axle. Once warmed up it seems to run OK. but with intermittent stumble. P0300, random misfire mostly cyl 2 & 8 ,dealer checked plugs and wires and found nothing wrong.They performed fuel injector service and replaced one fuel injector. Problem is better, but still there. They are thinking carbon buildup, possibly a bad tank of gas (38k miles) They have contacted GM engineering for guidance. 2 weeks and counting!
07-07-2018, 12:51 AM
#7
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Seems strange that the wires would just pop off. Any ideas why this happens?
07-07-2018, 07:39 AM
#8
Racer
Thread Starter
Car only has 1200 miles on it so it was a surprise to me to. I suspect it has something to do with it being a vertical connection. Maybe something bumped the line just enough to loosen it partially. It could also be that the vibration of the engine loosened a bad wire. I am going to keep an eye on it and have the dealer replace the wire if it happens again
07-07-2018, 07:40 AM
#9
Race Director
Plug wires don't just fall off, but if one is not properly connected in the first place, then its just a matter of time before it comes off. Really though, this is nothing to worry about, provided the wire is not damaged in some way, say because it was touching the exhaust manifold, or the metal end inside the boot is damaged and wont hold the plug, or there's a carbon track in the plug boot.
07-07-2018, 07:42 AM
#10
Race Director
Car only has 1200 miles on it so it was a surprise to me to. I suspect it has something to do with it being a vertical connection. Maybe something bumped the line just enough to loosen it partially. It could also be that the vibration of the engine loosened a bad wire. I am going to keep an eye on it and have the dealer replace the wire if it happens again
It almost certain the wire wasn't seated all the way if the first place.
No big deal.
Last edited by PatternDayTrader; 07-07-2018 at 07:42 AM.
07-07-2018, 07:47 AM
#11
Racer
Thread Starter
The wire was leaning against the valve cover when I looked in but it looked like it was still in the “plugged in” position. If I hadn’t been looking specifically for a loose wire I would have easily missed it. My guess is that it was always a little loose but I will have to keep an eye on it
07-07-2018, 11:35 AM
#14
Racer
Thread Starter
I’m hoping this is a one off although I have a bad feeling it won’t be. If it happens again I will have the dealer look at it and/or replace the wire. Unfortunately I couldn’t get the valve cover off so I needed to put the plug back on by feel. Luckily this was on the driver’s side. Not sure I could have put my hand under the passenger’s side valve cover.
07-07-2018, 11:48 AM
#15
Instructor
So my 2018 Grand Sport scared the crap out of me today. I was driving home from physical therapy when the car started to sputter when I would hit the gas. I made it home and when I did I got an error message in the DIC about Stabilitrak and service rear axle. After some heavy forum reading, and a little bit of panic, I came across a thread mentioning to check the spark plug wires. So I opened the hood to check and lo and behold the wire for I believe #5 cylinder was dangling from under the cover. I plugged it back in as best I could (hopefully I got it back in tight) and restarted the engine and it sounds good again with no error conditions. Anyone know if this is a common and/or recurring problem and if I should get anything checked out to make sure it didn’t hurt the engine (since it ran on 7 cylinders basically coming home)?
I do have first hand knowledge of the Service Rear Axle. I saw this DIC message two times and one rear axle overheat on a 7300 mile road trip. (RT 66)
It was a software glitch and was reprogramed with Gm service bulletin #17-NA-369 at the Dealership in Bellevue WA
07-07-2018, 01:13 PM
#17
Instructor
I think you are owed another Free flash. The warranty was filed as GM powertrain warranty claim code was GM # 37E95
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blueray16 (07-07-2018)
08-18-2019, 06:11 AM
#18
Consider yourself very fortunate.
I ran into the same problem. Heavy misfire especially when cold, CEL, then the service stabilitrack warning followed by the service rear axle. Once warmed up it seems to run OK. but with intermittent stumble. P0300, random misfire mostly cyl 2 & 8 ,dealer checked plugs and wires and found nothing wrong.They performed fuel injector service and replaced one fuel injector. Problem is better, but still there. They are thinking carbon buildup, possibly a bad tank of gas (38k miles) They have contacted GM engineering for guidance. 2 weeks and counting!
I ran into the same problem. Heavy misfire especially when cold, CEL, then the service stabilitrack warning followed by the service rear axle. Once warmed up it seems to run OK. but with intermittent stumble. P0300, random misfire mostly cyl 2 & 8 ,dealer checked plugs and wires and found nothing wrong.They performed fuel injector service and replaced one fuel injector. Problem is better, but still there. They are thinking carbon buildup, possibly a bad tank of gas (38k miles) They have contacted GM engineering for guidance. 2 weeks and counting!
I ordered new wires today anyway.
08-18-2019, 06:18 AM
#19
08-18-2019, 11:05 AM
#20
Burning Brakes
[QUOTE=BMF82;1599991520]What came of this? I am experiencing the same problem. Thought it was bad gas too. Took it to the dealer and they did the latest triple flush on the tranny thinking that would fix it. Wrong.
QUOTE]
Well, in my case it took 6 weeks to finally solve the problem. In addition to what I already mentioned they found heavy carbon deposits on the intake valves, did compression test and found and replaced a cracked valve spring. Took it on an extended 50 mile road test and all was well. Left it overnight and next morning the miss was back.
Finally they went ahead and replaced the engine control module,under warranty and haven't had a single issue with the car since. That' s a full year and 16,000 miles with zero problems.
FYI, the ECM is warrantied for 8 years or 80,000 miles.
PM me if you have any more questions
QUOTE]
Well, in my case it took 6 weeks to finally solve the problem. In addition to what I already mentioned they found heavy carbon deposits on the intake valves, did compression test and found and replaced a cracked valve spring. Took it on an extended 50 mile road test and all was well. Left it overnight and next morning the miss was back.
Finally they went ahead and replaced the engine control module,under warranty and haven't had a single issue with the car since. That' s a full year and 16,000 miles with zero problems.
FYI, the ECM is warrantied for 8 years or 80,000 miles.
PM me if you have any more questions
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Bavaria (08-18-2019)