2008 Impala SS engine hesitation/shudder

[cweathe]

Im at a lost and im sure since this is a great website that it might have been covered.

No check engine lights.

Let me start by saying I have had the transmission checked, as well as changed fluid. Catalytic converter checked, air filter, new belt. 76k+ miles

Doesnt matter if its hot or cold outside, engine either.

Randomly from stopped position the car hesitates then surges forward. Also at times accelerating from stopped the engine shudders, and surges.

Guy at muffler shop said possible misfire, but havent checked plugs yet, and also read that throttle body could be gummy/clogged.

Anyone have any suggestions. Was going to change spark plugs this weekend but would like a new lead if possible.

THanks for any help.

[GMCustomerService]

Hello cweathe,
Have you worked with a dealership at any point during this diagnosis process? As your vehicle is a 2008, and you are under 100,000miles, you are very likely still within the powertrain warranty, and if this concern is related to a covered component the repair may be warrantied. Would you like for me to check into the parameters of your vehicle's warranty? I can do that, but need the last 8 of the VIN, which you can get to me through a private message if you like.
Thanks,
Sarah
GM Customer Service

[cweathe]

Yes I did. I went in thinking it was a transmission error. An hour after I dropped off car the dealer contacted me and advised that since they found no problems. Told me that since there was no code on first inspection I was to be charge 50+ dollars for technicians fee.

Argued the fee seeing as how there was a problem regardless of "codes"

Also called regional GM manager about this as well and was told same thing. That when they check for a problem without a "code" that there is still a charge for technicians fee if they dont find anything.

Problem still exists, and car is still within paramaters of warranty that I know for sure. Sorry a little hesitant about giving info over forum.

[rkvons]

When you say it surges forward while idling do you mean a single surge, or a series of surges, like the engine is loping? I had the loping and it turned out to be really badly fouled injectors. Have you tried running Chevron Techron injector cleaner through? It might help.

[cweathe]

Ive had it do both and yes I ran some Techron Injector cleaner through it.
When it surges its like a clogged pipe that opens up abruptly, and the shudders are more so a transmission slipping feeling.

Dont know whats left. This morning...no problems at all. Its more often than not, but just odd.

Going to change plugs I guess this weekend. Im sure they are due, but curious if something else isnt happening internally that might be catastrophic later on.

[GMCustomerService]

I can understand why you're frustrated. Did you have a Service Request set up? If you send me that number, I can look into the case (fully understand the desire to protect information).

Sarah
GM Customer Service

[difrnc8]

i have a 2008 chevy impala ss too. when i read this post i brought it down to my folks at the shop and said " This is exactly what is happening to my car." i have had this problem for 2 years now, had transmission flushed, spark plugs, and engine coil. still not fixed. evertime i take it in to have it looked at, they cant find issue. But Its There! let me know what happened with your communication with that GM rep went. I love this car, but that hesitation is driving me nuts. Also, my neighbor had an 09 ss, same thing, but not as often as my car.

[GMCustomerService]

Originally Posted by difrnc8

i have a 2008 chevy impala ss too. when i read this post i brought it down to my folks at the shop and said " This is exactly what is happening to my car." i have had this problem for 2 years now, had transmission flushed, spark plugs, and engine coil. still not fixed. evertime i take it in to have it looked at, they cant find issue. But Its There! let me know what happened with your communication with that GM rep went. I love this car, but that hesitation is driving me nuts. Also, my neighbor had an 09 ss, same thing, but not as often as my car.

Good morning difrnc8,

I'm sorry you're also experiencing this concern! If I can look into your warranty information for you, check for open recalls, or assist in working with a dealership, please let me know! I would need the last 8 digits of your VIN to check into warranty/recall information, which you can send to me here on the forum in a private message.

All the best,
Sarah
GM Customer Service

[cweathe]

I took my car back into a different dealership and mechanic went on ride along with me and this time was able to "hear" the noise but not the hesitation.
After keeping it over a weekend the mechanic did find that one of my motor mounts was broken and replaced it. This was only after a visual inspection of the transmission yielded no defects. Might want to have them check to make sure one isnt broken.

After about 2 days, the noise and hesitation came back. I took car back in and informed them that possible other mount had now broken, but to no luck they couldnt find the "noise"

Service manager went on ride along with me and noise occured one time on ride along (only occurs between 15-20 mph).

Told him that I would drive for a few weeks and return when occuring more. STill happening but was informed that its possibly the belt tensionser pulley that could be making noise. I have to inform everyone that at one point driving on the freeway my belt tensioner came off the motor and bolt thread jacked. Was lucky enough to tow car back and tensioner landed on lower "a" arm of car. Had to rethread bolt hole and was able to reinstall.

Possible pulley causing noise, but havent had money to buy new one. Worth a shot.

Have mechanic check motor mounts first though.

[cweathe]

I must add they said possible surging was due to clogged injectors as once thought above and I purchased the dealers "injector cleaning service" on first visit, and still have problem.

[legotech7]

Well I hope we both can find some help.Ok, I searched all the forums, and apparently there are a lot of folks with this problem, but cannot find any concrete answers. I hope I can get help here.
Here is my problem and or symptoms on my 2000 Impala LS, 3.8 eng.
When I start it up, when the eng. is cold, the car starts right up and about a second or two it starts to hesitate or like its starving for fuel, like it wants to stall. But if I rev. it, to about 2000 rpm for a few seconds till it stabilizes, it will idle fine after that and continues to drive fine for the rest of the day. It only does it when the eng. is cold. I replaced the EGR valve, the fuel pressure regulator, PVC valve,fuel filter. Ran some fuel injector fluid in the gas tank, Removed the throttle body and cleaned it ( looks like new now ), sprayed some MAF cleaner on the sensor.......... AND its still doing the same thing. Oh... and I replaced the o2 sensor not too long ago. What the hell am I missing? Do I need to check my coils, plugs, plug wires, or perhaps the Idle Air Control valve? The car runs beautiful, not a miss, gets good gas mileage and has lots of power. It has 185,000 plus miles on it and Ive had since new. But this fuel starvation thing is driving me crazy. Anyone with any Ideas, or what other tests should I be running to resolve this? Any help would be very much appreciated.

[maxwedge]

A full scan and look at sensor inputs during the event look at the coolant temp sensor inputs, also check fuel pressure during the event, a leaking injector can cause this also, see if the engine holds fuel pressure when shut off.

[Shane Allen]

I feel your pain man, the exact same issues have been going on with my Impala SS also., the shudder, everything. Thank the Lord I was able to leave it with the dealership for a few weeks until they did find some sort of error code. They have now replaced my transmission and also my engine mount. I will try to get the error code for you when I go in to pick my car back up.

[Lordsknight]

Having same problem with our 2008 Impala. Driving around 35-50 mph, you can feel a slight surging and watch the tachometer surge as well.

I read on another thread, (can't find it now), this particular guy changed everything you could imagine with no luck. Finally he changed something called the lower cam sensor??? (I think that is the name) and that seemed to solve the problem. Anyone familiar with that?

[MockStar]

I also have this problem. I have a 2008 Impala LTZ with near 88,000 miles. When taking off from a complete stop and sometimes just when depressing the gas pedal fairly heavily while driving ( say when turning at an intersection at a slow speed) the car is not reactive to the acceleration for a quick second, and then it will jolt forward. Also, the shudder that others have experienced when accelerating also happens to me with my car. I, too, took it to the dealer since I just purchased the car outright and was told that there are no codes and the mechanics cannot reproduce the issue and therefore , basically, there are no issues as far as they are concerned. I am thinking about selling this car while it's still got under 100k simply because of this issue. Has anyone seen this car maintain operation for any length of time despite this issue? I mean, will I get another several thousand miles on it despite this issue or should I sell it now? No one seems to have the answer to the issue..