undecided1965

Only one dealer with Corvette Certified Tech within 30 miles.
Do you know if there are hidden codes even if no CEL?

MikeinAZ

I dont believe so, they ran lots of tests and couldn't find an issue but drove it with their computer on board and saw the timing was off. Once they submittwd it back to GM tech line, that is when they determined it was a bad cam sensor magnet.

2xsl_1998

@FCCCVPMan mine didn't have a check engine light either. Have them read the technical service bulletin in the link above. This is evidently a pretty common problem and I had the same issue with the cam position sensor that @MikeinAZ had. The bulletin number is Bulletin #22-NA-080

MY70THAnv

They have had my car for 8days and have driven it more than 130 Miles, they can duplicate the problem but cannot come up with a cause or solution. They say the only code is a misfire on cylinder 7. Loosing faith in the dealer and GM. So said.

hawkandersonjr

My guess is it will be cylinder number 7 lifter about to go.

MikeinAZ

I bet that injector is failing......why not change that? Sounds like you need a new dealer man. Shouldnt be this difficult! I had it diagnosed (bad cam magnet) in 2 days, Parts came in, I took car back and had it back 4 days later and that was the entire engine being removed and put back in.

MY70THAnv

Got a call from the dealership they said they have finally figured out what is going on with my car. They said that they have found a bad injector. They asked GM for permission to replace all four in that section. They hope to have an approval and the replacement parts installed by end of day Friday.

MY70THAnv

They called me today and said it was a bad injector. They are going to order a replacement part. They asked GM if they could replace all four in that section. Not really sure what that means but they hope to have it back together and to me by Friday afternoon. Then maybe I can take it out and make sure they really got it corrected.

MikeinAZ

just what I said....it was either an injector or cam magnet. Thank God you don't need to pull the engine.

So they are replacing all 4 injectors on that side of the engine while they are doing the faulty one. Call this a win, hopefully you get the car back in a couple days and it's running like a champ. Btw, tell them to skip the wash....

2xsl_1998

glad to hear you don't have to drop the engine!

MY70THAnv

After 2 weeks, a 150 miles and half a tank of gas. It’s back home. It took me almost 6 hours to get it back to the clean it was when I dropped it off but so far no more shutter. They replaced the fuel injector for cylinder seven.

MikeinAZ

Great to hear.....yeah its hard driving a filthy car home but the feeling of your baby running right again is totally worth it!! Glad it ended up being a pretty simple fix in the end.

maxbrutus

I have now gone through multiple dealers in the area that basically are refusing to find out what is going on with my 2023 C8 z51 75th Anniversary. They claim to be driving it and can’t get the issue to reproduce. No one will do a drive along or let me borrow the computer. I am at an absolute loss. This is a 100 grand hunk of metal.

The vehicle is unsafe to drive as the flashing engine light comes on after the stuttering occurs. It shows a p0300 “engine misfire detected” but the techs claim nothing else shows up on extended diagnostics. They tell me not to drive if the engine light flashes and to immediately take it to service. Which I did, and now they say they can’t reproduce the issue and can’t do anything until that happens consistently to them. They won’t look under the hood at all until something shows on their computer. They don’t care about existing events or the data that may shown in onboard logs.

I have high resolution video from the PDR showing the tach stuttering like crazy as well as phone footage from inside the vehicle when the issue occurs. Video of the engine light flashing. The issue occurred a dozen times on a 4 hour drive back home recently but it’s completely random.

GM does nothing. They say they stand behind their dealers decisions and to find another dealer that can work with you to reproduce the issue. I have no where else to go in the area. Is this really what new Corvette owners get to look forward to when choosing a Chevy product? Absolutely zero help when something clearly is faulty on a major luxury purchase?

The dealers of course charge a fee to diagnose the vehicle, even with the engine light flashing. They take their fee and say sorry it appears there is nothing wrong.

Does this tachometer seizure when in cruise control, going a consistent speed, look like nothing is wrong? I’m tired of feeling like the engine is going to die and I will be stuck in a vehicle with a complete loss of power, going high speeds on an interstate. Those bounces on the tach are actual points where the engine cuts out completely and then comes back on, rapid fire, several times a second. Be sure to click the YouTube cog and choose 1080p to see the clearest footage.



[Embedded YouTube description]
Video pulled from the onboard PDR showing tachometer seizures. Vehicle driving in cruise control at a consistent speed between 1500 and 1800 RPM in new C8 75th anniversary. Engine stuttering is accompanied by an extremely jerky driving experience that physically moves you in your seat as the engine power rapidly cuts off and then back on several times a second for up to a minute at a time. Flashing yellow check engine light occurs following the events and stops after a minute of flashing. Premium gasoline used.

Multiple dealers unwilling to fix the issue or assist in diagnosing in any way even after “engine misfire detected” codes showing up in the onboard computer diagnostics.

undecided1965

Did you try calling GM?

RKCRLR

Yep, GM's official position is to play dealer roulette. I went through that which eventually resulted in a buyback of my C7. When you say the dealers charge a diagnostic fee, are you paying the fee or is GM? You shouldn't be paying a diagnostic fee if your B2B warranty is still intact.

I'd start the complaint escalation process as listed in the back of the owner's manual at this point.
​​​​​​

maxbrutus

The dealers are charging the fee, and my warranty is fully intact. They are saying if the repair falls under the warranty, then the fee is waived but then they’re coming back and saying there’s nothing wrong with the vehicle and they can’t reproduce the issue regardless of the video and check engine light and then I have to pay the several hundred dollar fee to pick up the vehicle. Convenient right?

One dealer had the Corvette at their service department for a month. One would not test drive it more than once with their technician, whom drove around town going less than 30 mph, and said there was nothing wrong with the vehicle, and to come back when it was happening more often.

I have called GM multiple times.

RKCRLR

I'm surprised the dealer is charging you for the diagnostic fee. Yes, it is true that if the problem isn't diagnosed then it can't be charged back under warranty but GM is usually good at picking up the tab in those situations IF the car is still within the B2B warranty period. I've had several "unable to duplicate" diagnosis and have never been charged. Also, once the problem is diagnosed the diagnostic fees can charged back (assuming the problem is covered under warranty).

I'd definitely start the customer satisfaction procedure and at the very least request the diagnostic fees be reimbursed. It isn't your fault that the problem can't be reproduced. Hopefully dealer management will request a field tech get involved. Below is what is listed in my 2020 manual, your manual probably says the same or is close:

Customer Satisfaction
Procedure
Your satisfaction and goodwill are
important to your dealer and to
Chevrolet. Normally, any concerns
with the sales transaction or the
operation of the vehicle will be
resolved by your dealer's sales or
service departments. Sometimes,
however, despite the best intentions
of all concerned, misunderstandings
can occur. If your concern has not
been resolved to your satisfaction,
the following steps should be taken:
STEP ONE : Discuss your concern
with a member of dealership
management. Normally, concerns
can be quickly resolved at that level.
If the matter has already been
reviewed with the sales, service,
or parts manager, contact the owner
of your dealership or the general
manager.
STEP TWO : If after contacting a
member of dealership management,
it appears your concern cannot be304 Customer Information
resolved by your dealership without
further help, in the U.S., call the
Chevrolet Customer Assistance
Center at 1-800-222-1020. In
Canada, call General Motors of
Canada Customer Care Centre at
1-800-263-3777 (English),
or 1-800-263-7854 (French).
We encourage you to call the
toll-free number in order to give your
inquiry prompt attention. Have the
following information available to
give the Customer Assistance
representative:
. Vehicle Identification
Number (VIN). This is available
from the vehicle registration or
title, or the plate at the top left of
the instrument panel and visible
through the windshield.
. Dealership name and location.
. Vehicle delivery date and
present mileage.
When contacting Chevrolet,
remember that your concern will
likely be resolved at a dealer's
facility. That is why we suggest
following Step One first.
STEP THREE — U.S. Owners :
Both General Motors and your
dealer are committed to making
sure you are completely satisfied
with your new vehicle. However,
if you continue to remain unsatisfied
after following the procedure
outlined in Steps One and Two, you
can file with the Better Business
Bureau (BBB) Auto Line Program to
enforce your rights.
The BBB Auto Line Program is an
out-of-court program administered
by BBB National Programs, Inc. to
settle automotive disputes regarding
vehicle repairs or the interpretation
of the New Vehicle Limited
Warranty. Although you may be
required to resort to this informal
dispute resolution program prior to
filing a court action, use of the
program is free of charge and your
case will generally be heard within
40 days. If you do not agree with the
decision given in your case, you
may reject it and proceed with any
other venue for relief available
to you.
You may contact the BBB Auto Line
Program using the toll-free
telephone number or write them at
the following address:
BBB Auto Line Program
BBB National Programs, Inc.
3033 Wilson Boulevard
Suite 600
Arlington, VA 22201
Telephone: 1-800-955-5100
http://www.bbb.org/council/
programs-services/
dispute-handling-and-resolution/
bbb-auto-line
This program is available in all
50 states and the District of
Columbia. Eligibility is limited by
vehicle age, mileage, and other
factors. General Motors reserves
the right to change eligibility
limitations and/or discontinue its
participation in this program.

MikeinAZ

That is what my tach did too but I never got a cel. Mine ended up being a bad cam magnet but as we've seen above, a bad injector can produce a similar symptom. I'd talk to a service manager about possibly checking timing, that's what got them going down the rabbit hole on mine was timing was off, causing that fluttering of rpm. I'm sure there is an equally simple.way to see if each cylinder is firing correctly to check the injectors. Seems strange no dealer is willing to dig a little.

Michael A

These dealers sound like crooks. If the check engine light is coming on, then there are error codes. If there are error codes, then there is a problem, and it's not your problem, it's their problem. They don't need to replicate the problem. There are error codes in the computer. Maybe they are just too stupid to know how to retrieve the codes.
Stupid or lazy, one or the other. I'd file a claim with BBB demanding a refund for the diagnostic charges. I would also file a claim with your state's automotive repair department. They are ripping people off.

If the dealer had it for a month without fixing it, then you may be eligible to a lemon law buyback.

maxbrutus

FINALLY found a tech at the service department to drive it until the issue promulgated and they got the stuttering to re-create. Showed up on the computer as a bad camshaft magnet leading to a timing issue.

So for anyone that reads this thread in the future, just keep on your techs and get them to drive it until the issue promulgates if they can’t seem to re-create it. Don’t let them tell you it’s your fault and to come back when it gets worse.

Thanks to RKCRLR for his tips about the back of the customer service manual. I did not realize I had as many rights as I had. Thanks to all for your feedback and advice! I really didn’t want to have to lemon it as the wrap I had done wouldn’t have been covered.