Go Back   Corvette Forum > C6 Corvette, 2005 - 2013 > C6 Tech/Performance
Sign in using an external account
Register Forgot Password?
Register Search Today's Posts Mark Forums Read FAQ Vendor Directory
Search
C6 Tech/Performance
LS2, LS3, LS7, LS9 Corvette Technical Info, Internal Engine, External Engine, Tech Topics, Basic Tech, Maintenance, How to Remove & Replace Sponsored by
21st Century Muscle Cars

Welcome to Corvetteforum.com!
Welcome to Corvetteforum.com.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join Corvetteforum.com today!


Corvette Store
 
 
C7 Parts & Accessories
C6 Parts & Accessories
C5 Parts & Accessories
C4 Parts & Accessories
C3 Parts & Accessories
C2 Parts & Accessories
C1 Parts & Accessories
Wheels & Tires
Sponsored Ads
 
 
Vendor Directory
  
Reply
 
 
 
 
Thread Tools Search this Thread
Old 06-15-2013, 07:01 AM   #1
RocketDawg
CF Senior Member
CI 6-7-8 Veteran
St. Jude Donor '09
 
Member Since: Sep 2004
Location: Madison (Huntsville) Alabama
Send a message via Yahoo to RocketDawg
Default Running a bit rough

Haven't been on the Corvette Forum in quite a while ... according to my last login, it was over 3 years ago. Since then, I've bought an '09 Vette to replace my wrecked '03. The new purchase is a GM Certified Pre-Owned car and has a 2-year, bumper-to-bumper warranty.

The one I bought last September had just over 12,000 miles so it had "sat up" a lot ... averaged maybe 4,000 miles/year.

It's been running a bit rough ... "missing" at idle, and another perhaps related symptom ... "surging" when coasting down from highway speeds.

I took it to Dealer A twice ... the first time, he replaces several things, like vacuum hoses, and I think he even replaced the computer module. But the problem continued. I took it back a second time and he could find nothing ... told me that since it's a performance it's built and tuned "on the edge" I couldn't expect it to run really smoothly.

So I took it to Dealer B a couple of weeks ago. He kept it for 3 days and while he was able to duplicate the complaints, he could find nothing mechanically wrong ... pulled the plugs, checked the injector balance, and many other things ... and the only thing he could come up with was moisture in the gas. Said the fuel volatility was "extremely low". So he advised putting in a bottle of AC Delco "Fuel System Treatment Plus" to remove the moisture. I did that, and the car actually ran worse for a while, and still does to some degree.

Going up a hill, it seems to downshift too easily, and you can feel the engine missing a bit. It still idles a little rough. And when coasting from highway speeds, a "surge" can be felt. If I shift into Neutral, the surging goes away so it's not tires. At full throttle, it seems to run just fine.

I'm going to put some Techron in the tank at next fill-up, so it'll have two shots and several hundred miles for the treatments to work. If the problems still exist, I'm going to take it back in to Dealer B and ask them to check again ... things like coil pack, plug wires, and torque converter (for the surging issue).

Anybody else had a similar problem or any ideas? Since it had not been driven much, and with ethanol in gasoline these days, I can see how water in the gas could be a real issue. But at the moment, it doesn't seem to be. I don't know how long it takes to remove moisture using the gas treatments but I would assume a tankful should do the trick. If I still have the problem after another service visit, I'll call GM and see if they can offer a solution.
RocketDawg is offline   Reply With Quote
Old 06-15-2013, 09:37 AM   #2
truckplay
CF Senior Member
 
truckplay's Avatar
 
Member Since: Oct 2010
Location: Sugarhill Ga
Send a message via AIM to truckplay
Default

fuel additives are not needed if you run good fuel except when stored for a while, then use fuel stabil. try cleaning the MASS and throttle body & while you are in there chech your clamps on the intake tube and filter.
__________________


Tom
truckplay is offline   Reply With Quote
Old 06-15-2013, 11:40 AM   #3
1fastbob
CF Senior Member
Support Corvetteforum!
 
1fastbob's Avatar
 
Member Since: Dec 2010
Location: South Central Kansas
Default

I agree with truckplay, clean the MAS. Do NOT touch it with anything but the proper cleaning spray. Also does your Corvette have an aftermarket air intake system? Some of them have air flow turbulence issues that cause similar problems.
1fastbob is offline   Reply With Quote
Old 06-15-2013, 12:58 PM   #4
RocketDawg
CF Senior Member
CI 6-7-8 Veteran
St. Jude Donor '09
 
Member Since: Sep 2004
Location: Madison (Huntsville) Alabama
Send a message via Yahoo to RocketDawg
Default

No, it's totally stock.

Thanks for the replies.
RocketDawg is offline   Reply With Quote
Old 06-15-2013, 01:01 PM   #5
ELP_JC
CF Senior Member
 
Member Since: Dec 2006
Default

Yep, definitely check that you have the stock intake AND stock filter. If you have one of those crappy (for street use) oiled filters, then there's your answer. And yes, clean your MAF sensor too. And finally, switch to Chevron (or other tier-1) fuel. By your symptoms, it's a fueling issue IMO. Good luck.
ELP_JC is offline   Reply With Quote
Old 06-17-2013, 09:25 PM   #6
Gearhead Jim
CF Senior Member
St. Jude Donor '13
Support Corvetteforum!
 
Member Since: Sep 2000
Location: Crystal Lake, IL
Default

Many people, but not everyone, with the LS3 engine (like our 2009) experience a "stutter" or "shudder" when letting off the gas at highway speeds, could that be one of the things you are experiencing?
"It's not a bug, it's a feature."
Causes no problems, and can't be "fixed", if that is indeed what is happening.
Gearhead Jim is offline   Reply With Quote
Old 06-24-2013, 05:17 AM   #7
RocketDawg
CF Senior Member
CI 6-7-8 Veteran
St. Jude Donor '09
 
Member Since: Sep 2004
Location: Madison (Huntsville) Alabama
Send a message via Yahoo to RocketDawg
Default

Thanks to the responders to my post, I THINK I have the issues fixed. I took the car back into Dealer B last Thursday. The fuel additives had absolutely no positive effect, and the stumbling and pulsing issues still existed.

The service guy didn't seem all that thrilled to see me ... they'd kept it 3 days the time before and the only think they could come up with was moisture in the gas. I told him that several posters on the Corvette Forum had recommended cleaning the Mass Air Flow Sensor. He didn't want to do that because there was no code. But I asked him to just humor me and at least check the thing. He said he would, but he'd like to keep it several days to "research" the problems. I think what he really wanted to do was to keep it long enough so that I'd never take it back.

But the next afternoon, he called, said they'd checked the MAS and it was defective. They replaced it and it seemed to have mostly cleared up the issues I was having. I went to pick it up and he actually seemed a little sheepish ... apparently because the Forum had solved something that they couldn't.

After several days now the car seems to be running fine. My thanks to the forum for quickly assessing the problem and suggesting a fix. I suppose dealer mechanics nowadays just work by codes and can't really analyze a problem and find a solution.

By the way, everything was done under warranty so it cost me nothing except gas to go to the dealer several times, my time, and the cost of the fuel additive. And the additive probably cleaned out some junk anyway. Thanks again.
RocketDawg is offline   Reply With Quote
Old 06-24-2013, 09:31 AM   #8
dennis50nj
CF Senior Member
 
dennis50nj's Avatar
 
Member Since: Mar 2005
Location: Southampton NJ
Default

Quote:
Originally Posted by RocketDawg View Post
Thanks to the responders to my post, I THINK I have the issues fixed. I took the car back into Dealer B last Thursday. The fuel additives had absolutely no positive effect, and the stumbling and pulsing issues still existed.

The service guy didn't seem all that thrilled to see me ... they'd kept it 3 days the time before and the only think they could come up with was moisture in the gas. I told him that several posters on the Corvette Forum had recommended cleaning the Mass Air Flow Sensor. He didn't want to do that because there was no code. But I asked him to just humor me and at least check the thing. He said he would, but he'd like to keep it several days to "research" the problems. I think what he really wanted to do was to keep it long enough so that I'd never take it back.

But the next afternoon, he called, said they'd checked the MAS and it was defective. They replaced it and it seemed to have mostly cleared up the issues I was having. I went to pick it up and he actually seemed a little sheepish ... apparently because the Forum had solved something that they couldn't.

After several days now the car seems to be running fine. My thanks to the forum for quickly assessing the problem and suggesting a fix. I suppose dealer mechanics nowadays just work by codes and can't really analyze a problem and find a solution.

By the way, everything was done under warranty so it cost me nothing except gas to go to the dealer several times, my time, and the cost of the fuel additive. And the additive probably cleaned out some junk anyway. Thanks again.
Drop in more often
dennis50nj is offline   Reply With Quote
Old 06-24-2013, 09:31 AM
 
Go Back   Corvette Forum > C6 Corvette, 2005 - 2013 > C6 Tech/Performance
Reload this Page Running a bit rough
 
 
 
Reply


Thread Tools Search this Thread
Search this Thread:

Click for Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel, Carburetor or Something Else? roy69 C3 Tech/Performance 4 10-06-2014 09:47 AM
82 running rough and surges Shawnee C3 Tech/Performance 5 06-02-2014 09:36 PM
Home moisture problem (before you click, this is long)) Aerovette Off Topic 60 06-19-2013 09:52 AM
Engine surges after installing K&N CAI NHRA95 C6 Z06 Discussion 35 12-14-2008 08:12 PM
Frustrated after AR header install suprjet2 C6 Z06 Discussion 29 10-19-2007 09:24 AM


All times are GMT -4. The time now is 04:00 PM.


Emails & Password Backup