hoek30

I have been having a couple issues with my 23 Corvette. I have a real bad stumble during idle and it feels almost how a loose motor mount would feel as you can feel and hear an audible tapping especially when the engine is shut off. Along with that, when the car is revved up around 1300 it get a real bad shake like the motor is turning over and then smooths out. Ran it up to the dealer to look at and GM wants to throw a set of new spark plugs in on Monday see if it fixes the issues before the dealership will look into it further. Has anyone ran into this yet?

Andybump

Were there any codes? The car has sensors that will detect a misfire, even pinpointing which cylinder. Misfire can be caused by spark plugs, spark plug wires, ignition coil issues, fuel injector issues, even valve issues. If there is a code there is a diagnostic procedure to follow that should lead to a diagnosis. It would be unusual that all the plugs are faulty. If there is no code - then yeah they have to try stuff. Or if the diagnostic procedure results were ambiguous they have to try stuff. If they contacted GM, it sound like maybe they could not diagnose it for some reason.

hoek30

No codes were thrown. They keep trying to default to the fact that these engines will have a rougher idle than usual per GM. The car also jerks real bad when put into drive. I requested that the main tech sit in the car, so they can hear and feel all the issues

Andybump

Sounds not right to me. Yes, mine will shake ever so slightly at idle after first started up and for a little while, but not like you are describing. I do not notice much and especially after driving any distance I do not notice it. And, I don't have any extreme jerks under any conditions.

There is a transmission service fast learn procedure that may address the shifting roughness. This procedure "performs a series of individual clutch applications which allows the control module K71to learn initial clutch apply pressures. The control module uses the learn values for clutch control and timing of shifts." The procedure is required after certain components are serviced, repaired or replaced. I do not know if they will perform it just because the shifting is rough. Normally their training is to only perform procedures if led there by a DTC and diagnostic procedure.

Red Mist Rulz

It's under warranty, so letting them change the plugs isn't going to cost you anything. and to do that they need to pull off the bottom plates, so if there really is a broken mount they'll be able to see it. Hopefully. If it doesn't fix it (and it probably won't) then they can move on to the next thing. Not much else you can do but let them work through their progression.

hoek30

The only issue I have is their experience working on the C8 since they are a small town rural dealer. I am hoping after the plugs (if they don’t work) they will escalate it to a specialist. I been through the wringer with a gt350 eating up the engine so I don’t think it can be worse than that lol.

Vetteman Jack

and hope your dealer can figure this out sooner rather than later.

hoek30

Update from the dealer. They are still installing plugs going on day 3. They found some voltage issues throwing codes. They think it was the aftermarket battery put in before i bought the car. Putting in an oem battery on my dime.

ArizonaZ06

An aftermarket battery on practically a new 23 C8. What type of aftermarket battery was installed in being such a new build? AGM or maybe a Lithium ion? Somewhat doubt if those two types could cause a prior voltage issue..

449er

let your warranty work for you

hoek30

Pretty much was told they wouldn’t dig further into the voltage issues with the aftermarket battery being in the car.

hoek30

Idle is still erratic and missing after the spark plug change. Tech can hear a noise but the service manager suggests letting it get worse and throw a code before they can start to fix it. I’m about ready to punt this POS for another GT500.