CEL comes on when driving in rain

[orion2011]

So my car has an issue which I am not sure how to solve. I installed a CAI intake, a doing thorley exhaust, and then went back to the intake to install the ADM scoop afterwards. The last two times it has rained, my car has thrown a check engine light while driving during these conditions. Note, the code has only come on then, and never appears during the close to 300 or 400 miles at least that I have put on it without rain. Coincidence? I do not think so. :( Long story short, I clean up my intake box, and notice it has dry water around the heat shield, and I began to suspect whether the water getting thrown through the scoop and towards the intake might be what is causing it? The code I can not remember off the top of my head, for it has been a while, but it states that "fuel trim is too lean." My second guess could be that I have an O2 sensor that might be loose and is getting wet, causing the code to be thrown? Whatever the problem is, it is caused by water. When it has shown up, I unplug the battery, pop the hood, and unplug the MAF sensor in case it gets wet and let it dry. I then go back the next morning, reinstall everything, and the code doesn't come back unless driven in the rain. If anyone knows an answer to this issue, I would be happy to hear any feedback.

-R. L., Fellow Camaro owner

EDIT: The code that was thrown was P0174 "System lean, Bank 2"

http://www.camaro5.com/forums/showthread.php?t=172698

I read through the issue that this guy had, but I have no headers nor a tune or anything like that, just bolt ons. I am becoming more convinced it could be the O2 sensors...

[orion2011]

buump

[JDP Tech]

Does your MAF sensor show any signs of water on it? You're on the right track, O2 sensors read if the engine is running rich or lean, the MAF is where the computer gets the info to calculate the proper fuel. So if it does in fact have something to do with rain or moisture, unless you have a fuel delivery problem when it rains, then I'd look at the front O2 sensors or the MAF. Is it bank 2 every time?

Feel free to call, email or PM us anytime!
- Jeremy

[orion2011]

Originally Posted by JDP Tech

Does your MAF sensor show any signs of water on it? You're on the right track, O2 sensors read if the engine is running rich or lean, the MAF is where the computer gets the info to calculate the proper fuel. So if it does in fact have something to do with rain or moisture, unless you have a fuel delivery problem when it rains, then I'd look at the front O2 sensors or the MAF. Is it bank 2 every time?

Feel free to call, email or PM us anytime!
- Jeremy

Hi thanks for the information! both times it has happened before christmas. The first time it happened, autozone scanned it and I got that one single code. I drove it in the rain later, and the light came on again, but I didn't take it to be scanned again as I assumed it was the same code and could be corrected by leaving the hood up overnight, unplugging the battery, and disconnecting the MAF sensor. I live in Dallas and the last two days have been rainy and assuming the code would come back, I opted to not drive it until today. Would there be a way for me to check the O2 sensors myself? When I checked the MAF sensor, it didn't look wet :/ but I can not be certain.

[orion2011]

^the code has gone away both times and my currently does not have it.

[Oxtar41]

Does the car chug at all and does the light flash or just stay on? I have seen bad plug wires cause a miss when its humid out or they get wet. The light sometimes will flash and go off but the code will stay stored.

EDIT: NVM didnt see that it was a lean code.