Posted in General but no one must look at those threads

Ok I'm ripping my hair out over here. Here's a description of the problem...

Only happens when shifting from first to second gear under partial throttle, and when I shift between 2200RPM and 3300RPM

The "stutter" or "jerking" is similar to pressing the throttle and releasing it rapidly, it only stops if I release throttle then floor it and slowly release to desired throttle position.

I've replaced MAF Sensor, Map sensor, Throttle body, and still does it. Replacing throttle body solved the issue for about a day then it returned.

Is there anything I am missing, anything I should check. this is frustrating as hell

Thanks in advance for the help guys.

 

Stop spam posting this say thread because you didnt get an answer in a few hours.

 

I'm not spamming just messed up and posted in in LNF section so I erased the content of it.

 

Miles on car?

Tuned?

Does it do it when car is warmed up? Cold? etc

 

89XXX Miles, It is trifecta Tuned, and it seems to do it more when its cold but I have noticed it after the car has been warmed up

 

I have noticed a moderate jerking when my car is cold as of late. Need to hook the scanner up to it and see what's going on.

Have you ever cleaned your intake valves or had them looked at?

 

I have not, I didn't even think of that. To be honest it seems to be an electrical issue, imo but if I knew what was going on i would be on here right? Haha...
Like I said its only going into second and its violent as if you were flooring the pedal and releasing it constantly

 

Mine has been doing it since day one, no amount of tuning or engine rebuilding has ever changed anything, and yes it is more prominent when it is cold. I don't even have an LSJ. lol I'f i dont let the car warm up and pull away from it being dead cold, it will jerk back and fourth exactly like that, like the throttle is being pressed and let off and pressed and let off. I've also had numerous issues on both cobalt's we have here with them being just dead on power when you try to pull away with the engine cold, it either wont respond to the gas pedal and struggle to get moving or will pull away real fast and then drop power instantly. Again, all goes away immediately once it gets above i wanna say 100 degrees on ECt and the engine starts getting warm.

 

That seems a lot like what mine is doing except mine will do it while warm too. I've got a remote start on mine so it's usually been running for 10min or so before I drive off in it, coolant temps are usually around 150-170 and it will still do it. So you have not found a cause for this... That worries me

 

Always presumed it was either the cam phasers not being able to flow oil properly and being jerky, or something with the throttle body and the drive by wire system, but since this is happening on yours as well and its not a 2.4. Not sure what it could be exactly.

 

Does it do it if you shift higher? Like 3500 instead of 3200. I would only assume the shift at 2200 is ******* the ever living crap out of the engine hence the jerking.

 

^^Yes it will do it up to about 4k to and it's only under partial throttle, I've sent trifecta a few datalogs and they never said anything about it. Do you think the pedal itself might be going, but that would not explain why its only partial throttle and in second gear

 

Well here's a list of the mods idk if it might help;

LSJ
ZZP Longtube headers and 3" catted DP
Ported M62 on 2.6" Pulley
Option B, Dual Pass, Secondary HE
80s
LNF 3.82 Trans w/LSD
Trifecta tune

It was doing the same thing with the TVS on it, i thought it was the SC so i put the M62 back on but that didnt fix anything.

 

I had the exact same issue with my old LSJ, But unfortunately I never got to figure it out.

But I did change my plugs and coils and was about to do injectors, Was suggested it might be my fuel filter or to look at my tune. These are a couple things to think about I didn't do much planning after that to be honest since I never even got to install my injectors.

Hope this helps, Keep us posted.

 

plugs are new just changed about 500 miles ago. Im gonna do the timing chain and check the valves as suggested. I'm hoping one of those things will fix it.

 

mine does the jerking bull and i drive in alot of traffic so u can imagine its very annoying

to me the car reacts like its about to stall and its bucking itself around. rpms are always above 1k and it does it around 2000-2500 just guessing i dont pay attention to it much any more

to stop it i push the clutch in and try to hold a constant speed at a different rpm.

mainly does it in 1st and 2nd. but has bucked in other grinds not as bad tho

replaced tb, upstream o2 sensor, spark plugs, cleaned air filter and washed the car jk haha

 

Are you on 80s also? I'm wondering if there is an issue with the lower load on the injector spraying to much fuel so when you shift it spikes really rich. Anyone who has this issue have a wideband installed?

 

I have a Wideband and an interceptor, Ive tried watching both when it does it but its too distracting to try to watch the guages and pay attention to the road. I guess i could put my gopro on record and watch the video later and see what it is doing.

 

Yea sound very similar to mine but mine will jerk right up to damn near 4k if i let it

 

Does it have a 0-5volt out put? That would make it easy to log and easy to look at in a spread sheet vs. trying to look at the video and input it into a spread sheet.

 

im on 60s, i have aem wideband and interceptor

my car has a rough idle which i had since the 60s and 2.8 upgrade back in 2010.

my car may have always done this but for 8 yrs worked 15mins from home with little to no freeway driving.

 

Yes it has a 0-5v output and i actually have it hooked up to my Aeroforce on one of the Analog inputs

No rough idle on mine, problem is under partial throttle.

 

It kind of goes from normal idle to rough. Like cammed haha
But back to the jerking madness haha

Partial throttle is accurate for me aswell, if I try to give it more gas once it
Starts jerking it will ramp up or balance out. Clutch in works most all the time

 

I still can't figure it out, I have NO idea what to look for anymore

 

my car broke on Friday haha p0335 but it drives fine now

i did a 2nd to 3rd pull and it died, let it cool down and drove off into the sunset. Im gonna get the sensor replaced as this will be the 2nd time. 1st time it was actually the battery dying

code is crankshaft position sensor