Hi, I'm new. I was sifting through threads on this. But I guess I'm still going to ask my question and give my scenario.


05' Cobalt-
I got my car back in March this year, used obviously. Anyway my car was running like a champ. Until I brought him in for an oil change. I specifically told them, just change my oil. Nothing else. Don't give me a trie rotation, alignment check, don't touch ANYTHING! The reason was, they gave me a bunch of bullshit about my other car when they were looking at it.

So anyway, a few days after my oil change, my car started acting funny. Twice the rpms dropped for a moment engine shuttered a little, that was is it. The next day it got a little worse happened a few more times. I started getting pissed, in my mind, I started thinking they did something to my car where I got my oil change. First of all they were rude to me, secondly I'm a girl, so I think they think they can walk all over me, which is why I'm ******* hellbent on learning about my car. Anyway the next day the rpms dropped to zero but I could accelerate with my engine acting all stupid. I thought my car was going to blow the **** up. The tachometer was bouncing all over like a retard. No check engine light for the whole day. (Note- this occurrence was only happening when accelerating or hitting bumps)
The next day the check engine light popped up brought it to get the code. Which was the crankshaft sensor sensor code.
Went and got a new one. My boyfriend replaced it. I told him to double check that wires were not loose, I had read in my research that was a problem sometimes. It worked! For about 20 minutes.

Now today its doing the exact same thing!!! But now I can hardly accelerate. Its like the car completely shuts off! My accessories are all still on but I can't accelerate. Then it'll kick back on I can accelerate but my engine is bouncing around, then I can't accelerate, then I can... it still seems like bumps make it worse. Any ideas?? I'm so stressed out!!!!

 

Any more codes after replacing the CKP?

I've experienced a bad CKP.. Hitting bumps would make the RPMs drop, coasting in neutral (manual) would make the engine die and not start back up, etc. It's not fun on the highway.

 

Almost sounds like a bad fuel pump maybe

 

My car has the exact same problem only mine started after rebuilding her and starting it up for the first time, i replaced my CPS as well still does the same thing and i drive a 09 SS sedan. but my rpm are all over the place and she start n runs like **** but will die if i dont giv it gas...

 

Same problems here after replacing the crank position sensor. My car will keep running even with the tach not working

 

Does it matter if you replace it with a part from say auto zone or get it from the dealership? I replaced mine with one from auto zone. Bad idea?

 

No more codes. Or at least the check engine light hasn't popped up, even when its getting really bad.

 

You might have to perform a case learn via hp tuners or tech 2

Because you replaced the crank sensor

 

Not necessarily. You can usually never go wrong with OEM, although aftermarket can work just as fine.
Maybe this is your next step^.

Does your car have a hard time starting up?

 

Could also be the case, but I didn't have to. $50 at my dealership to have it done. I did it for peace of mind, but the car drove fine for days after installing the new sensor.

 

I've read that it varies from car to car. Some people have to, some dont

 

Driving on it like it is without doing so.. is it damaging?

 

No, but you'll most likely have a code for it and your car won't run as good as it should.

It's hard to diagnose over the Internet, honestly.

 

So a code will pop up if I need it? Can the car throw codes that won't make the check engine light come on??

 

Yes. Get the car scanned, if you can.

 

Not since all this, and even so its had issues maybe like three.times since Sunday starting... I've started it quite a bit.

 

Would a fuel pump cause the tach to go down?? My friend drove it said it feels like the transmission is slipping. Whatever that means..

 

Need a crankcase relearn.

 

So we found that there is cuts in the wire. The place that changed my oil cut wires!!!!!!!!

 

They cut two wires going to the crankcase!

 

I took pictures of it, but don't know how to get them up here. You can see tool marks all over the wire casing a chunk just fell off.

 

If your BF can change the CKP, he can definitely do an oil change. This is why you don't do oil changes at shops.

Upload the pics to photo bucket or image shack and post the link here.

 

He normally would have, but my mom bought me one. My car runs perfectly now :-)