When the car is cold I'm having problems with hesitations when you give it any kind of hard"er" throttle. Shifting between gears causes the car to essentially buck before starting to accelerate. The problem goes away when the car warms up.

I've replaced:

Spark Plugs
Ignition Coils
Fuel Injectors (almost a year ago now, maybe I put the wrong ones in? The car sputtered pretty bad when I first installed them)

Any ideas on what I can check? Also my car has an aftermarket exhaust and it REALLY pops and almost backfires when I let off gas in gear but not when cold, only when it's warmed up.

Thoughts?

 

Auto or manual? And by cold, do you mean you start it up and go? How long and how often does it do this? Video?

 

This exact thing happens to me as well, the remedy I found was just rev it higher (3500) and shift quicker, instead of taking my time.

 

Sorry. 2006 Cobalt SS 2.4 Manual.

Happens when it's cooler outside and engine has not been ran in a few hours. If it's a hot day I don't think I normally notice it but yeah if I run it for a min or so then go it has trouble for probably the first 5-10 mins of driving.

 

Mine does this exact same thing. I figured I'd clean the throttle body with throttle body cleaner of course and now my rpms hang when I'm in neutral... You talk about annoying.

 

What about codes? Have you replaced your int and ext cam sensors recently?

 

Codes? Have you changed your int and ext cam sensors?

 

No codes are present as of right now. I did replace both exhaust and intake cam actuator solenoids recently. I guess it could've been wrong part perhaps?

 

I have replaced both cam actuator solenoids too, my rpms are still surging reving up and down repeatedly, causes the whole car to buck forward. I have replaced spark plugs, fuel filter, air intake upgraded, new throttle body. I'm beginning to either think it is the MAF or throttle position pedal sensor . Its not throwing any codes, or misfires. It started 3 weeks after i bought it last june and its still happening. I have had so many mechanics look at it they are lost in how to fix the problem.

 

I had a similar problem at one point as I know it may sound simple disconnect your battery for a 10 minutes or so and then reconnect. Resets everything.

 

yeah. i tried lol. Anyone know about TCC lock-up?? because as i decelerate it has a hard time .

 

Yeah I think a good spray down of the MAF wouldn't hurt.

Throttle Body cleaning.

Maybe try running a 1/3 of a can of seafoam through the bitch.

 

i sprayed maf lol im thinking maybe buy a new one and i put in a brand new throttle body. I used seafoam like twice now. and changed oil twice since ive had it. i bought her at 27k last june . problems started july. No codes, no misfire.
It has a hard time staying at low speed like 30 mph-45 mph. and starts rpm surges and bucking. once i get to higher speeds shes fine but when i get to lower speeds she starts reving up and down. When i accelerate her power bogs down.

 

What do your AFRs look like? Maybe new 02 sensor.

Hate to throw parts at it.

 

yeah everyone thinks its tcc, ecu, tcm, maf, fuel pump, fuel injector

 

holy christ; yall ninjas just throwing parts at cars

Whats your ETC, IAT, O2 readings, ect. when you take off?
Whats your ECT, IAT, O2 readings, ect. when it goes away?

Before you start throwing a shitload of parts at a car, look at what the **** is going on...

 

You got chemical inside the throttle body electronics...get a new one

You put in ACdelcos? What are you seeing to make you think you need to replace them, are your vvt %'s all over the place?

What parts did you put on(brand)?
What is the APP doing?
There isnt a TPS on the electronic throttle body cars...


Have you taken it to a shop with employees that know what they are doing or are familiar with the ecotec?

 

Acdelco. My bad//correction- cobalt accelerator position sensor.

yeah taken it to several mechanics some that were familiar with gm/ ecotec. Maguire chevrolet had a chevy specialist look at it for 2 weeks. I'm talking to GM headquarters tomorrow on the phone. I've had this rpm surge/bucking problem for way too long its been going on since july 2013, and i bought it in june 2013 with 27k, it started having problems surging/bucking stalling 500 miles later. The first problem was the stalling it threw codes for camshaft solenoid(exhaust) so i replaced both exhaust and intake solenoids. which cured the stalling, but the jerking and rpm surges still existed. So i replaced the original oem sparkplugs with ngk iridium acdelco sparks to see if that would cure the problem. It didnt, so i replaced the fuel filter that was a negative too. Changed the oil, and seafoamed her. problem still existed. my stock intake needed to be replaced so i put in k&n intake and new filter. The problem still occured. Every mechanic was set in saying it was my Throttle Body and Mass air flow. I replaced both recently. The problem is getting worse and mechanics are like confused on what to pursue now.

 

All I did was simple tune-ups that needed to be done, because the person who owned it before me clearly never took care of it- When i looked at the camshaft solenoids that was a clear sign especially at 27k. So hold on there- clearly i have spent my money wisely. ( i cleaned the throttle body and maf) the mechanics told me they needed to be replaced which i did not agree with myself, but once again i proved them it was not the right move on their part. All I'm just asking for helpful hints . The only code that recently has been thrown was my 02 sensor p0141 which disappeared.

 

fuel filter