Misfires and o2 sensor problem

[mrivera95]

Hello all, I need some advice on where to start.

I have a 2005 pontiac vibe gt that I bought with a p0171 lean code on it. Was hunting for the culprit but never found anything. My spark plugs looked good and my gas mileage was pretty alright for a 180xxx mile car. was averaging 28 when driving very conservatively. Car died at a red light the other day and I ended up changing the fuel pump and it ran, but kept blowing the efi fuse. When trying to find a shorting wire, i unplugged the upstream o2 sensor and it still blew the fuse. I plugged it back in, and found this connector that wasnt connected to anything but had a pin pushed into it. I assume to jump the connector. Took the pin out and the fuses havent blown since.

Now that i said the back story, the CEL is on, and i got it read at the auto store 3 times, each time i reset the car by unplugging the battery for about an hour. The first time was a code for misfire in 3 cylinders and an o2 sensor showing that the heater control circuit is low. The second time, no misfires but 3 codes all pertaining to the upstream o2 sensor going out p2195 p0134 p0031. The third time, and this time i drove a good amount of miles to let everything run, and the codes were p0301,p0302,p0303,p0304, p0300 and p0031. The first 4 are misfires in all cylinders, then its a code for a random misfire, and the last is for the h02s heater control circuit low.

My thought is that the o2 sensor is the root of the problem. The sensor looks very very rusted so, theres a good chance its the original. Anyone else have advice? Also, if anyone is able to look under their hood, can you tell me what the connector that is coming off the harness right after the positive battery terminal is. I can take a picture if needed.

[zbyers]

Do you have a bluetooth code reader? If so, you can hook it up and pull the o2 sensor data. if it has a nice "wave" on the graph, the sensors are doing their job. Only the first sensor is really critical.

P0031 for the o2 sensor basically says it has low/no voltage. I will ask the obvious, did you plug the sensor back in? lol. I know many who've forgotten to plug things back in.

I would probably throw in new plugs. Even if they look good, they are one of the first things I do when buying a car from someone. That way I know when they were last done.

Your P0171 is a small vacuum leak. If it has an a cold air or short ram intake, it could be from that. most don't hook up the vacuum lines properly when installing. Not as common on the 2zz, but the intake manifold gasket is another source of that code.

I'm not sure what connector you're referring to. Post a pic if you get a chance.

[mrivera95]

Do you have a bluetooth code reader? If so, you can hook it up and pull the o2 sensor data. if it has a nice "wave" on the graph, the sensors are doing their job. Only the first sensor is really critical.

P0031 for the o2 sensor basically says it has low/no voltage. I will ask the obvious, did you plug the sensor back in? lol. I know many who've forgotten to plug things back in.

I would probably throw in new plugs. Even if they look good, they are one of the first things I do when buying a car from someone. That way I know when they were last done.

Your P0171 is a small vacuum leak. If it has an a cold air or short ram intake, it could be from that. most don't hook up the vacuum lines properly when installing. Not as common on the 2zz, but the intake manifold gasket is another source of that code.

I'm not sure what connector you're referring to. Post a pic if you get a chance.

I've just been going to the auto store and having them read me the codes. I may buy a scanner is needed. I do have a COI but I haven't found a diagram of the stock airbox so I can check if it's right. Just checking my looking for open hose fittings or disconnected/damped hoses. Checked intake manifold gasket with carb cleaner and there was no stutter

[mrivera95]

Do you have a bluetooth code reader? If so, you can hook it up and pull the o2 sensor data. if it has a nice "wave" on the graph, the sensors are doing their job. Only the first sensor is really critical.

P0031 for the o2 sensor basically says it has low/no voltage. I will ask the obvious, did you plug the sensor back in? lol. I know many who've forgotten to plug things back in.

I would probably throw in new plugs. Even if they look good, they are one of the first things I do when buying a car from someone. That way I know when they were last done.

Your P0171 is a small vacuum leak. If it has an a cold air or short ram intake, it could be from that. most don't hook up the vacuum lines properly when installing. Not as common on the 2zz, but the intake manifold gasket is another source of that code.

I'm not sure what connector you're referring to. Post a pic if you get a chance.

[zbyers]

That connector is potentially the source of your P0171 code. I know it is part of the VSV contraptions located closer to the master cylinder.

I will post a pic of my setup when I get home, to show you how the wires are plugged, and the vacuum hoses are routed for the intake.

[mrivera95]

That connector is potentially the source of your P0171 code. I know it is part of the VSV contraptions located closer to the master cylinder.

I will post a pic of my setup when I get home, to show you how the wires are plugged, and the vacuum hoses are routed for the intake.

Please ans thank you! I dont know why someone was jumping it with a pin shoved into it

[mrivera95]

Another note I forgot to say was that whenever I reset the computer by disconnecting the battery, it drives real bad for the first miles. After a couple times driving it drives fine. No bad gas mileage, sounds like its firing on all cylinders. I wanna say the power doesn't feel effected after either but I could easy have had this problem this whole time so I don't know

[zbyers]

Another note I forgot to say was that whenever I reset the computer by disconnecting the battery, it drives real bad for the first miles. After a couple times driving it drives fine. No bad gas mileage, sounds like its firing on all cylinders. I wanna say the power doesn't feel effected after either but I could easy have had this problem this whole time so I don't know

after disconnecting battery, the car needs to relearn it's idle, and it will idle pretty rough. Best bet is to let it sit and idle for 5-10 minutes, and you should be good.

That pin on the plug under the dash was probably jumped to simulate being plugged in. it would basically do the same thing either way.

[mrivera95]

Another note I forgot to say was that whenever I reset the computer by disconnecting the battery, it drives real bad for the first miles. After a couple times driving it drives fine. No bad gas mileage, sounds like its firing on all cylinders. I wanna say the power doesn't feel effected after either but I could easy have had this problem this whole time so I don't know

after disconnecting battery, the car needs to relearn it's idle, and it will idle pretty rough. Best bet is to let it sit and idle for 5-10 minutes, and you should be good.

That pin on the plug under the dash was probably jumped to simulate being plugged in. it would basically do the same thing either way.

That gives me some piece of mind.
So, I looked at the o2 sensor and sure enough... it was unplugged. I guess i didnt plug it in all the way to have it click, and putting the floor mat back over it probably pulled it out. Ill be driving a a good 40 miles today so ill be able to see how it drives and if the CEL comes back on.

My big problem was that my efi fuse kept blowing, and i have a feeling it is because of that pin in the connector. The way the connector was hanging, it potentially was touching other components and/or the frame

[mrivera95]

That connector is potentially the source of your P0171 code. I know it is part of the VSV contraptions located closer to the master cylinder.

I will post a pic of my setup when I get home, to show you how the wires are plugged, and the vacuum hoses are routed for the intake.

Any luck on pictures of your setup? Or seeing what that connector plugs into?