So, as the sig states, I'm an owner of an 08 SS/TC.

I've noticed an interesting phenomenon, where as if I'm moving along and let my foot off the gas quickly, the car will feel as though it's jerking back and forth a little after about 1/4 of a second without throttle.

Now I have to state, that I've not driven a manual before this, but do understand the concepts associated with such, that a slight jerking is prone to happen due to the nature of the beast. However, there seems to be varying degrees of this, most of which I can assume are just natural. However, there are some that are much more violent and I fear the results of if the roads were icy/etc.

Of course replicating this for the dealer will be a task, atleast one of the more violent ones, as it seems to be almost completely random as to whether or not it will be a smooth little hiccup, or not. But given the upcoming road conditions, it's something that if it's a genuine problem, I'd like to get it taken care of ASAP.

So the long and short of it is do you think this is normal or is this something I should genuinely bring up and address? I will be having my car in next week as my bloody ebrake no longer works. (and for the record, I only pull it to park!) ;)

Thanks

 

I had this in my ss/sc. I replaced the sparkplugs and it went away.

 

It is perfectly normal. All drive by wire cars seem to be a little jerky with the throttle. Also, the cobalts have decelartion fuel cutoff where the car shuts off the fuel injectors when you are above certain RPM and you goto 0 throttle. The DFCO can cause a little bit of jerkiness as well.

 

That is probably your problem. My car does the exact same thing. I hate drive by wire.

 

DFCO enables above 1500rpm, and disables when you go below 1250rpm stock

 

my redline is herky jerky plugs don't matter. I'd say it's dfco but what do I know.

 

or maybe u'r just letting off the clutch to early lol

 

All modern fuel injected GM vehicles shut off fuel when you let go of the accelerator pedal, so the engine isnt actually "running" when your coasting in gear and above about 1500rpm. SO youve got a coasting car spinning the the trans and engine, if you let off the clutch or gas quickly you get a sudden change in power and the car will "rock"

Be smooth with your throttle and clutch application and you will limit this happening to a great degree. SMOOTH is the key to safe winter driving as well

 

DFCO doesn't kick in right away, there is a slight delay, almost a second or so. That is designed to eliminate a laggy response if you just breifly take your foot off the gas and step back down. If it fully cut fuel every time, it would get irritating.

Sounds to me like normal drivetrain lash, its quite severe on these cars.

 

Side note: I really hate seeing so many posts about and people referring to the fuel cutoff as DFCO like its some amazing thing or a feature that you can "use"

DFCO is one of the biggest improvement offered by electronic fuel injection, being able to shut off fuel was one of the main reason that EFI was even created! Its repsonsible for a huge portion of the reduction in hydrocarbon emissions between carb and EFI engines.

Its just fuel injection, get over it

 

Agreed, people act like its something that has a real effect, like if you didn't have it, you would really notice a difference other than worse emissions and bad gas milage.

I turned it off on my car just for the exhaust burble on decel, and that is the only change it made. Its a nothing feature, it doesn't cause any jerkiness or anything like that.

 

What about backlash with the gears in the transmission caused by going from he acceleration side of the gear to the deceleration side of the gear...

I could be way off base but it was just a thought...

 

Repost

 

Sorry bro. I didn't see that you posted that up...what can I say? Great minds think alike LOL

 

Thanks for the information, pretty much confirmed what I suspected. I had been watching my HPTuners logs during some of these and everything seemed mostly normal (this coming from someone who doesn't know much about cars ... I've noticed the slight delay before the DFCO kicked on that seemed to coincide with the jerkiness.

I'm coming from an auto with no power (go go neon sxt), so the manual operations and quirks are a bit new. Just figured I'd see what the consensus was

As for the statement about smooth transitions I have to say, the slower I remove my foot from the pedal, sometimes the worse it is. That is all on my part though, as I reach the end of the throttle, it blips between 0 and 1% or whatever the number may in fact be due to the jerking of the car.

 

SLOW ≠ SMOOTH smooth = smooth


You need to find the right speed for engaging the clutch and applying the throttle.

 

its normal
although after being tuned i have found this doesnt happen