Need help with stranded C7 please!
Thread Starter
Instructor
Joined: Mar 2017
Posts: 239
Likes: 30
From: Columbus, GA
Need help with stranded C7 please!
Good afternoon everyone, I have a 2014 Z51 C7 with 55k miles. I was in third gear at about 2k RPMs when suddenly I felt some very slight shaking coming from the rear. About 3-4 seconds later my CEL started blinking and I received the “service stabilitrak” as well as “service rear diff” (I think) and the traction control light came on. The car was sputtering and it almost felt like I was running on 4 cylinders. The car shut off on me and I decided to crank it. It cranked for about 10 seconds and it started but then it died. Started it again and it died again. I let the car sit for a day and tried to start it and it started right up with no lights on the dash but after about 10 seconds the CEL started blinking so I **** the vehicle off. I should note that the night prior I was in a parking lot where noise was able to bounce back and I heard the slight hissing sound of a failing wheel bearing. The car is stranded and I’ll be getting it back today but I would like to know where to start looking. Thank you for your time!
Le Mans Master
Joined: Mar 2010
Posts: 7,044
Likes: 944
From: DFW TX
First step would be to pull the codes and see what the car is complaining of. Having issues with the rear end and the car dying because of it is strange.
Sounds weird, but I would get the battery tested.
Sounds weird, but I would get the battery tested.
Instructor
Joined: Mar 2018
Posts: 233
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See this thread https://www.corvetteforum.com/forums...rear-axle.html, starting with my post (#3).
In hindsight, I would have saved money if, after I got the codes, I simply bit the bullet and pulled the valve covers. I bought new coil packs, spark plugs, wires and MAP sensor, only to find that it was a broken valve spring.
Another way to put it: We all want to believe that the problem in cylinder 4 is electrical, but it could also be mechanical. However, if you are not getting a MAP sensor error, then it's probably only electrical.
In hindsight, I would have saved money if, after I got the codes, I simply bit the bullet and pulled the valve covers. I bought new coil packs, spark plugs, wires and MAP sensor, only to find that it was a broken valve spring.
Another way to put it: We all want to believe that the problem in cylinder 4 is electrical, but it could also be mechanical. However, if you are not getting a MAP sensor error, then it's probably only electrical.
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Thread Starter
Instructor
Joined: Mar 2017
Posts: 239
Likes: 30
From: Columbus, GA
Alright guys soI went ahead and swapped coil packs around and read the code that was stored before starting it with the swapped coils and the CEL I got was P0300 multiple random misfires.. I cleared it and turned the car on and the code that came on after about a minute was the P0300 again and no longer the Cyl 4 misfire. I should note that the car idles EXTREMELY ROUGH and the exhaust fumes smell pretty bad.. any ideas? Also, the previous owner had a bent pushrod replaced a thousand miles prior to this (I’ve owned it 1,000 miles and already having issues) it’s a 56K mile car. Thanks in advance!
Instructor
Joined: Mar 2018
Posts: 233
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Alright guys soI went ahead and swapped coil packs around and read the code that was stored before starting it with the swapped coils and the CEL I got was P0300 multiple random misfires.. I cleared it and turned the car on and the code that came on after about a minute was the P0300 again and no longer the Cyl 4 misfire. I should note that the car idles EXTREMELY ROUGH and the exhaust fumes smell pretty bad.. any ideas? Also, the previous owner had a bent pushrod replaced a thousand miles prior to this (I’ve owned it 1,000 miles and already having issues) it’s a 56K mile car. Thanks in advance!
Le Mans Master
Joined: Mar 2010
Posts: 7,044
Likes: 944
From: DFW TX
Alright guys soI went ahead and swapped coil packs around and read the code that was stored before starting it with the swapped coils and the CEL I got was P0300 multiple random misfires.. I cleared it and turned the car on and the code that came on after about a minute was the P0300 again and no longer the Cyl 4 misfire. I should note that the car idles EXTREMELY ROUGH and the exhaust fumes smell pretty bad.. any ideas? Also, the previous owner had a bent pushrod replaced a thousand miles prior to this (I’ve owned it 1,000 miles and already having issues) it’s a 56K mile car. Thanks in advance!
Thread Starter
Instructor
Joined: Mar 2017
Posts: 239
Likes: 30
From: Columbus, GA
Hey brother I did read your entire thread and unfortunately I’m starting to think I’m having the same issue.. the idle is rough but I’m not hearing any horrible sounds so I’m hoping if it is a spring it’s just cracked like yours. Thank you for the reply and link I really appreciate it!
Thread Starter
Instructor
Joined: Mar 2017
Posts: 239
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From: Columbus, GA
Safety Car
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From: in the country North Carolina
If he bent a pushrod odds are he over revved it. I'd check all of the pushrods and replace all of the valve springs. At a minimum. If not you're probably going to be looking a very big bill for a new engine. Fwiw.
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From: Bel Air (by way of Fort Worth, TX) Maryland
St. Jude Donor '12 thru '21
I was going to ask the OP when I read his initial post whether he was running the original battery in the car, as the initial symptoms he described indicated either a dead/dying battery or a problem with the main power connection to the battery.
After reading the entire thread and the OP's updates, it sounds like more than just the battery.
After reading the entire thread and the OP's updates, it sounds like more than just the battery.
Instructor
Joined: Mar 2018
Posts: 233
Likes: 69
Hey brother I did read your entire thread and unfortunately I’m starting to think I’m having the same issue.. the idle is rough but I’m not hearing any horrible sounds so I’m hoping if it is a spring it’s just cracked like yours. Thank you for the reply and link I really appreciate it!
Before I identified and changed the broken valve spring in my LT1, the engine would barely start and ran REALLY, REALLY ROUGH ... like I began to get a sinking feeling that there was serious damage. But the rough running noises were not too "metallic" in nature (no big knock sounds or anything) -- just a horrifically non-smooth engine that kept dying. I was cringing every time I tried to start it, especially because the gauge cluster takes a few seconds to report oil pressure. After a couple of those starts, I felt that I had better stop doing that :-) But after I replaced the valve springs (and upgraded the pushrods at the same time), it started smooth as can be on the first try.
Good luck, keep us posted!
Tech Contributor
Joined: Oct 1999
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From: Charlotte, NC (formerly Endicott, NY)
OP: are you able to read the history file that is stored for the P0300 code? P0300 can show when a misfire doesn't exceed a certain threshold to be allocated to a specific cylinder. However, the history file will usually give an indication of which cylinders are experiencing problems. For instance I was getting P0300 codes but the history file was showing cylinder number 8 was misfiring at a specific rpm and throttle opening. The file indicated the cylinder misfired 64 times at 5200 rpms at wide open throttle. Once the problem got worse I got a P0308 showing cylinder number 8 had misfired 521 times above 5200 rpm at wide open throttle.
I suspect moving the coil around just reduced the incident of misfire and cylinder number 4 is still the culprit.
Your diff messages are the result of the misfire. The eLSD can't work properly if there is a misfire so when an engine code that affects torque delivery comes up you can also get a diff message.
Bill
I suspect moving the coil around just reduced the incident of misfire and cylinder number 4 is still the culprit.
Your diff messages are the result of the misfire. The eLSD can't work properly if there is a misfire so when an engine code that affects torque delivery comes up you can also get a diff message.
Bill
Last edited by Bill Dearborn; Aug 19, 2020 at 03:30 PM.
Instructor
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How do you over rev a stock car? The limiter cuts you off at 6,600 rpm. I would think these engines would be safe till 7,000
