Hello all. This is my first posting. I recently bought a 2007 lsj cobalt ss. It is a project car that runs and drives sorta. I have replaced the sway bar link, and wheel bearing. I know that it needs a serpentine belt, slave cylinder, axle seal. I am having a big power loss/misfire in 2nd gear and only 2nd gear. Whether I downshift into it, or shift into 2nd. It will lag/misfire and you can hear it as well. I changed the spark plugs recently and the downpipe(due to a very large hole in it). What else could be the cause?

 

So it runs perfectly fine and feels like it has good power in all the other gears? Any CEL?

 

CEL? and yes it has power in all other gears like it normally would, but I get a lag/surge/misfire in 2nd gear and 2nd gear only, and it wont be there if I shift in high rpm from first or if I slowly accelerate to past 3000rpm. It goes away after about 3000-3500rpm

 

Check Engine Light is what I meant. I honestly don't know. This is far out there but would it be possible for the knock sensor to pick up some sort of vibration from the transmission and pull the timing enough to cause that? Just a wild guess honestly. Hopefully someone else has experienced this and can help you with it.

 

From other research I saw that it could be a bad ignition coil, air filter, or fuel filter. I'm changing the 2 filters tomorrow. but I'm trying to avoid ignition coil cause they can be pricey. The check engine light has been on for awhile but it is just for a coolant sensor

 

check the codes again

 

Before I put on my o2 sensor(I ran without one for a couple weeks) the 3 codes were coolant sensor, misfire and emissions. Then I put the o2 sensor in and the misfire and emissions went away. The only code now is that coolant sensor one, and I can get it cleared and it will be off for a day or 2 and then it comes back, same code

 

what is your coolant temp reading on the dash? coolant temp affects fueling and timing

 

Usually around 120, ive never had it go above 190