Just wondering if what I have going on is normal for the corvette or not. It almost seems as if it's got a small cam in it. I notice it at idle mostly. Everything seems to be stock on the car. Any info on this would be greatly appreciated!! Thank you!

 

what year is your car?
how many miles ?
if you had a cam you would hear it for sure!

you may need to give the maf a good cleaning and install fresh plug's and wire's give her a slight tune up would deft not hurt

 

Rumble as in shake or sound?

Bad engine mount?

 

It's a 2000 and has 35k on it. I bought it with 31K Last December. Probably needs exactly what you say, if it shouldn't be idling rough like that then.

 

No it's not a bad engine mount. I'd hear that especially on start up. It's a shake. No sounds. Just uneveness I guess you could say.

 

pop the hood and watch the motor while the car is running, I'd be willing to bet you can see quite a bit of movement... keep your eye on the alternator and it will be pretty obvious... it's normal but the stock mounts are not good when it comes to limiting drivetrain movement

 

Post a video... that would make it easier to help.

 

It's normal. Every C5 I've ever been in has a slight "shiver" at idle. If you had a chronic miss or ignition issue of some sort, you'll (eventually) get a CEL and DIC code.

 

If you can feel engine roughness and or vibrations sitting in the drivers/passengers seat, it is NOT NORMAL!

Yes the engine canand does move a bit on the type of engine mounts that the C5 has. THAT IS NORMAL AND THAT IS ANOTHER REASON THAT YOU SHOULDNT feel any engine harshness in the interior. The engine mounts soak up those issues. If you have a significant engine misfire, there are a couple of ways you can see it:

1- IF, you check the DTCs while the engine is running, you will see a P-0300 DTC

2- The Check Engine Light (CEL) will FLASH during PCM detected misfire if the P-0300 DTC is set.

HOWEVER,, the engine can run rough for several different reason and not set a DTC.

1- Dirty MAF
2- Un-metered air leak (Air leak in the ducting between the MAF and the Throttle Body or from a damaged / deteriorated / loose vacuum line/fitting
3- Loose Spark plug wire
4- Bad Spark plug wire
5- Dirty throttle blade & Throttle body throat.
6- Nasty air filter
7- Fouled plugs (NOTE) GM AC Delco Plugs are designed to last and run normaly for at least 100,000 miles (as per the GM guidance) Most change them around 50K-70K.
8 Damaged/ bad/ or defective coil
9Damaged/ bad/ or defective fuel injector


Your car sat for a LONG TIME. I strongly recommend that you run a couple of tanks of fuel with a treatment of CHEVRON TECHRON Fuel System cleaner!

Bill

PS

As I was logging on to CF, I was thinking, Man, I wonder how Cindy is making out with her car?? Been off the forum for a while and not keeping up with events.

 

I'm not trying to correct you, Bill, but I think this is definitely a case of personal subjectivity coming into play. I've been in C5's right off the showroom floor with < 100 mi. on them, and every single one of them had a subtle idle shiver that you could feel through the steering column. To me it always felt like the slightest bit of cam lope.

 

Maybe more so; she is not the original owner. There may be an aftermarket cam in there. But yes, IMO even the base model doesn't idle as smooth as a Honda Accord or sim...

 

My car did it from day one.
I ordered, waited, and took delivery of it with 4 miles on the odometer.

 

My 98 MN6 coupe NEVER had even the slightest bit of interior vibration/noise/harshness. I too purchased it new and it was always STOCK.

That being said, some people are a lot more sensitive to vibrations than others. Who knows what was done to the car previously. It was also in an accident.

Ive troubleshot a LOT of C5s and had crazy vibration issues cause by dozens of weird issues:

Broken exhaust mounts
Bad engine & differential mounts
Exhaust systems touching body parts
Poorly installed headers


So,, Just saying...

 

Cam profiles changed in later years. I wonder if that might be part of the difference?

 

I've had cars that you literally can't feel are running. This is my point...

 

Hey Bill!

I sent you a pm quite a while ago about the AC but never got a reply. I figured you must be busy since I haven't seen you on here much lately. I haven't been really either so who am I to say!

I will certainly do what you suggest just to rule out those possibilities. There are no codes currently coming up. I did send you all the codes that were showing then. Maybe it's in there?

Just wish I really knew if it was normal or not since we have a few differences of opinions. Now that we just put on my after market exhausts and they sound sooooo good, the loping just goes with the whole sound and feel! But, do want to check things over just to make sure.

Thanks for the advice Bill!!! Hope you are doing well btw?!

P.S. The vette needs a new front bumper as Extreme Dimensions sent the wrong one that wasn't updated for fitment....especially the turn signals which don't fit whatsoever! They are sending me a new one, but I'll have to get it painted and all, plus the hood needs to be redone also....can see the sanding marks he left and bits of junk in it. Also have a humming going on but think it might be the wheel bearings. If not, the tires. Always something it seems!

 

Well that's part of it at least. Reducing exhaust back-pressure will have the same effect as increasing valve overlap.

 

In layman's terms please

 

I'm speaking of a very slight engine vibration or "roughness" at idle. I noticed the idle rpm would vary just a little as well. I had no interior noise or harshness issues.

Completely agree. Some people also hear certain frequencies of sound more-so than others.

 

I feel it in the seat and the car itself shakes just a tiny bit. If that helps at all. All uneven....not steady. Again, like a small cam lope.