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Discussion Starter #1
I have encountered a new issue with my 2008 G6 4 cylinder. I bought the car new and it has 29,990 on it. What just started up now, and it's happened twice already, is that when you are going 30 MPH and giving it the gas to take the car up to 40 or more that very last shift the car makes it now slows the engine down or surges it. It almost feels like it's running out of gas. Then, within a minute, it slowly picks up speed again but then hesitates a bit after that. I'll take it to the dealer but I wanted to ask you guy's first. Anyone else with this problem? Thanks! Don
 

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Before you take it to the dealer: Is the check engine lamp on? If not, you should still check for pending codes (Autozone can do this free). Hesitation on acceleration can be caused by a lot of things. If there are no codes, & the dealer can't easily replicate the issue in a short test drive, they'll probably just shoo you out the door.

It could be as simple as a dirty MAF sensor or throttle body.
 

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Before you take it to the dealer: Is the check engine lamp on? If not, you should still check for pending codes (Autozone can do this free). Hesitation on acceleration can be caused by a lot of things. If there are no codes, & the dealer can't easily replicate the issue in a short test drive, they'll probably just shoo you out the door.

It could be as simple as a dirty MAF sensor or throttle body.
I was thinking you should try cleaning the TB or MAF if you have no check engine light.
 

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My car does something like this and I, too, have an 08 4cyl. The other day on the highway going about 50mph, I switched to the fast lane to try and accelerate past a slower moving car and it literally took a good 5-8 seconds for the car to gain ANY type of speed. It's almost like the engine refused to respond at all, despite the fact that the gas pedal was being pushed pretty close to the floor. When I first noticed this problem months ago, took it to the dealer and they hooked it up to the machine, a tech drove it, and they could find no problems w/the transmission. No codes are being thrown so of course that complicates the matter too. I'm at about to 58.6K miles and I was wondering if changing the transmission fluid would be of any help with this problem. Suggestions?
 

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Tranny fluid--No.

You should also start with cleaning the MAF sensor & TB. These are routine maintenance items on all modern cars though I realize they don't tell you that in the owner's manual.

Be careful with the MAF sensor. The only thing that should touch it is MAF sensor cleaning spray.
 

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Discussion Starter #6
No. I have no check engine lights. I was thinking maybe disconnecting the battery and reconnecting to reset something?
 

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Might be a torque converter or a 3rd gear apply piston in the trans...

Does the car switch back and forth from "overdrive"? Does it jerk forward when doing a rolling stop?
 

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Well that's good! lol.

Have you checked the fuel pump? Sometimes a sporatic fuel pump can cause really weird issues like this...being that u have no pcm codes. I had a Ranger that the fuel pump was going out. It would build up extreme pressure on initial start up and bog down like this on WOT or even accelerating up a hill because it couldn't keep a steady flow of gas to the injectors. Come to think of it...I never once had a pcm code or check engine light either.
 

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No. I have no check engine lights. I was thinking maybe disconnecting the battery and reconnecting to reset something?
Pending codes will not light the CEL so you should still check for codes. You can get a basic code reader for under 25 bucks now. If you disconnect the battery you'll lose all code info that might help in the diagnosis. It is always worth doing.
 

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Does the car switch back and forth from "overdrive"? Does it jerk forward when doing a rolling stop?
I HATE "overdrive"

(MPH)>97,98,99,100,.....101.....102.....103.....104.....105

Can you turn it off to do an experiment to see if that's the problem......for the guy having the problem, of course!!! :D
 

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2006 G6 GTP
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LOL. Overdrive actually means that your torque converter locks in place, running 1:1 with the engine and trans. Most people think it's a gear by itself. It can be turned off with a tech scanner or a wired up switch, but u would get HORRIBLE gas mileage in 3rd and 4th gear.
 

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Discussion Starter #14
Well, today's the day. I'm having my wife take the G6 to the dealer. I made the service manager a nice list. We'll see how far I get with that!
 

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Well. The car is back from the dealer and they say it's fine and there is nothing wrong with it. It's normal. The car shows no codes. I knew it was going to be a waste of time!
 

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2006 G6 GTP
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Well out definitely sounds like a "no gas" issue to me. Whether or not it is the tps or the fuel pump beats me. I think ur fuel pump is acting up, but it could be something as small as the tps or the pedal sensor. PCM's don't always pick up everything, but when they do they usually specifiy an area to begin. If u don't want to start buying every part that could "possibly" be bad. Just drive it until a CEL does pop up. One quick question tho: When was the last time the plugs were changed or have they been changed? I would definitely do the normal routine tune up (plugs, wires,etc.) stuff to it, just to eliminate the easy stuff first.
 

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The plugs have never been out. I'm going to take the car to my mechanic that I am good friends with and give him a ride in it and see what he thinks.
 

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With mine the problem most of the time was it would take off! And I mean it would smoke the front tires - - -very dangerous to drive.

Two different dealers told me there was nothing wrong with the car - - - I tried to have them drive it for a week and they refused!

Some times you would press the gas and it would go nowhere ( sounds like yours ) but the main problem was the running away. You would be driving about 25 to 30 MPH in town and the front tires would smoke as the car tried to breed the cars in front! As soon as you took you foor off the throttle it would come back to idle. The dealers replaced the throttle petal assmy 3 times but it seemed to help ( not cure ) the first two times, no help at all the last time.

I was so scared of the car I parked it for a year - - - I would not sell it as I did not want to be responcible for someone else getting killed.

After finding this site I changed the throttle body ( about $150.00 at Auto Zone ) and the car has been fine for about a month now. I went back to the dealer to see if they would pay for the throttle body and they refused as "Their computer showed there was nothing wrong with the car". They also refused to refund for the throttle petals they had sold me! ( I have three that are probably all fine )

In seeing the throttle body I feel I could have cleaned it and the car would have been fine. It was coated with a black tar in the throat causing the butterfly to try to stay closed and the small moter would build torque and break it loose and go to wide open then back to idle when you took your foot off the petal. You should see the black marks in the parking garage at my daughters appt. Smoking tires , blank space then skid marks!
 
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