Terminator2

When I am cruising at less than 2000 RPM the car shudders and bucks like its misfiring, but no code I dont have any way of monitoring for knock or anything. Anybody with similar problems or any suggestions. Help please!!!

PimpLay2

you are porbably knocking

are u driving slow in a high gear?

Terminator2

approximately 1500-1900 rpm 40-50 mph flat ground very little load on engine 6-10lbs vac.

MapOfTaziFoSho

Probably not. Knock is nearly undetectable by a person under most conditions. If you were knocking so badly as to it being felt...well you would have holes in your pistons.


There are a number of different things that can cause this...so lets get some more information.


When you get this bucking or shuddering...is the clutch fully engaged?

So you were in 5th gear...I'd simply recommend down-shifting to 4th gear.

Rissa

Are you keeping the same amount of pressure on the accelerator the whole time? Or are you lifting your foot off a lil bit?

Terminator2

Yes, I am In 5th gear constant light pressure on the throttle. If I press it down a little further its ok, which is weird. Is it telling the injectors to cut fuel like when you let off and coast?

freakta

iTrader: (1)

ya mine does that a bit if i floor it at too low of an rpm... thought it was kinda odd

Terminator2

I heard on the sky forums if you regap the factory plugs to 0.025 it may help with low rpm misfire. Any thoughts or people who have done this?

krispy

Is it a bucking or just a vibration?

I get vibration when under light throttle in 5th under 2k rpms, but thats not unusually IMO.

TrevMo

Are you resting your foot on the clutch (not pushing it in...just not taking it off all of the way)? I have a bad habit of doing this and sometimes I get this bucking...probably engaging the clutch slightly...

Terminator2

Possibly, but I don't think I am. I had heard the the DI mototrs in these cars are very smooth at low rpms in all the reviews, but having driven many stick shifts cars before this one seems to run rather rough down low.

Rissa

Mine only does anything even remotely close to that if I let my foot off the gas a little bit.

krispy

I think this may have more to do with hitting a resonance frequency between the drivetrain/chassis then an actual engine misfire issue.

PimpLay2

mine does it if the car has not been running for a while and i switch from 1st to 2nd around 3k RPMS

Jman2448

I think It's just the nature of the DI, mine a little bit of a miss feel @ low RPM's in 5th, uinder light throttle. Reminds me exatly how a rig does if you start moving it in to high of a gear.

1WhiteSSTC

interesting idea..........i'ma definately check into this when my cobalt arrives.

Terminator2

It is definately bucking a little you can feel. It is as if it is surging foward slightly then slowing down, and it does this almost constantly until I give it a little more throttle.

BowTieTillIdie

lol all engines do this with high torque learn to drive it better and you will not get the buck. It is because of lack of experience with the Clutch. No Big Deal. It is normal. Try driving a mazda b4000 manual truck. Thing bucks like you can't believe.. 5th gear is meant for 55+ lol going 45 in 5th should make it buck at low RPMS slowing down, I would be pissed too if I had to go from 10 mph to 55+ starting in 5th ofcourse the tranny is gunna want higher RPMs it's not your moms Subaru ... Watch a semi truck take off with no load sometime.

Terminator2

I have driven many much more powerful stick shift cars. A 2004 Viper Srt 10 (dads), 2005 ls2 GTO (last car). 1987 911 Turbo. Modified 1999 Mustang Gt. I know how to drive powerful cars. My 2008 2.3L ranger can hold 5th at 35-40mph no bucking at all. My mustang would hold 5th at 30 mph no bucking at all. I am not ragging on it in 5th or letting off and pressing the accelerator as I drive either.

rukkee

iTrader: (3)

Is it just a little drive train lash? There will always be a bit of gear lash in a manual transmission, that plus stock motor mounts can cause this.

Terminator2

It could be. But it feels more like a bog then surge. It is not like when your in first gear and you let off all of a sudden and it shakes and shutters.

supermantxz24

mine does that too

MapOfTaziFoSho

Naturally aspirated V6, V8 engines will behave differently than turbo charged 4 cylinder engines.

BowTieTillIdie

What a tard these are all front wheel drive vehicles


LOL

blackbird

I've noticed on my car that when cold and in 1st and 2nd gear at low speeds right after start up there's a little bit of driveline lash and bucking that is more noticeable with the A/C. I think that's normal though and is more than likely the engine calibration altering the timing and fueling to get the cat to light off faster. But if enough people take their car in for service then a manufacturer may sometimes try to release a flash/programming update but I haven't heard of anything so far for the new SS.

You can have light audible knock that won't damage an engine but it's hard to say it that's the case here. If you suspect knock or a misfire you could always try to monitor on a scan tool. I'd bet there probably isn't a problem with the car but you could always check the simple stuff like plugs and make sure there aren't any vacuum line or sensor issues. Also while the LNF pulls pretty well from low rpms and is very smooth, 1500 rpms is a little too low for 5th even though it will still pull the car on flat ground. It might just be a case of needing to modify your driving style, especially if you were used to higher displacement engines in the past that can inherently pull better at low rpms than a small displacement boosted engine.