Does anyone know why I keep getting this code? P0171

[BlkNBlkC5]

P0171 This is supposed to be a lean A/F ration code, I cleaned the MAF already. The check engine light keeps coming back on, but when I run the diagnostics, it shows up as a history code. If it is a history code I don't understand why the light keeps coming on, I have deleted the code twice and there are no other codes in the system. Does anyone have an idea as to why my car is doing this?

[9t8z28]

You can delete the code but it will still be in the history. You need to run the car 50 to 60 miles to get the code cleared off of the history (I think).?.
What all is done to the car?

[BlkNBlkC5]

Thanks, I deleted it before leaving Pheonix yesterday back to San Diego and it hasn't come back so I guess that was the problem. I don't know why it came up in the first place though... All I have done to the car is Vararam B2, TB bypass, 78mm LSX intake manifold, and Borla Stinger exaust.

[BlownC5]

This can happen when you make intake and exhaust improvements like you did. The stock baseline is a richer air/fuel mixture and by improving the flow of air in and out of the engine will lean the mixture. The car needs time to adjust and then you should see no more codes. :yup:

[tblu92]

I agree--you are giving the engine more air and therefor leaning it out--The computer will correct the fueling to a certain point then after tat you will have to get a tune--and re-do the fuel curve---ALSO--could be a bad tank of gas that plugged up yout fuel filter--clogged injectors--I would replace filter and run some of the chevron injector cleaner--i forget the name---something gaurd i think (it's the best)

[extanker]

your fuel trim is lean .get a scan tool and look at the O2 data. you may try a batt disconnect and idle relearn .check for air leaks. a good scan tool like snap on will spot this rightaway if ya read the data right

[BlkNBlkC5]

Thanks for all the advice guys, the problem seems to have corrected itself for now with a little injector cleaner and some octane booster in the following tank. I will be getting a tune next month when my headers come in. I did have another code come up which was U1160 H, another emissions management code that has something to do with a/f ratio, I'm just not sure what the 60 represents, regardless it is a history code and the service light is not on so hopefully that's the end of it...