Ive been trying to figure this code out for the past two weeks. CEL 51 means im running lean, and that either my map sensor, front o2 sensor, or my fuel injectors are shot. Now along with the CEL, the car hesitates and sputters after about 20 minutes of driving. The hesitation gets worse as the tempurature outside goes up. A weird thing tho, when it rains, the car runs MUCH better. Ive got an a/f ratio guage and it says im running VERY lean. Does anyone have a clue as to what it is, or anything i can do to find out what the problem is. Thanks

Everytime i post i never get a response, can someone PLEASE try and help me?

Well it could be any of the things you listed above really. First off, try some good fuel injector cleaner you can put in the gas tank. See if that does anything. It could be your map, or your o2, both have been known to go bad on our cars. You say your A/F gauge goes all the way lean? Does it go back and forth at all? Or does is just stay in the lean area?

When i start the car, the guage reads fine, but as it sits and runs it slowly goes to the lean side. My o2 is fairly new, i was really thinking its the map sensor, but i needed someone to back me up. Anyone else?

i got that code recently and i richened my afc and it hasn't come back on. on my gauge, it not go rich all the way like before. but after i messed with the afc, it's been running better. if the MAP sensor is the cause, let me know b/c i'll get one of those. i too recently replaced my o2 sensor so i know it's not that.
later

any news?
later

My car used to shoot that code when I didn't have my HRC down pipe welded to the stock down pipe so it wouldn't cycle the O2 sensor completely. But like you said, it may be one the 3. Good luck.

Guys, i really dont know what it is at the moment. i dont have the extra money to buy a map sensor and test it out. I also dont have an afc to adjust fuel trim. I'll keep you updated when i figure it out. Thanks for the help

ok, i cleaned my MAP sensor and no luck. so i put my buddies MAP sensor on my car and went for the a test drive. his is a 99 oz gs and i still got the same results. so i'm thinking this. when i richen my s-afc it runs a little better but consumes more gas. so my FPR is working fine. this leads me to think that it's either a clogged injector or fuel filter. any more input will be appreciated.
later

Well my fuel filter is brand new. I just installed it not too long ago and im still having the same problem. I guess the only thing to do is replace the injectors, but that might take a while. Other than that i have no clue. One thing is the car runs alot better when its raining outside. How could this affect anything?